JP2020036589A - Method and apparatus for suppressing growth of microorganisms using visible light LED - Google Patents

Abstract

To provide a method and apparatus in which the growth of microorganisms can effectively be suppressed.SOLUTION: Provided is a method for suppressing growth of microorganisms in a subject, comprising a step for performing visible light ray irradiation to the subject using a visible light LED as a light source, and in which, characterized, the irradiation is performed such that the peak wavelength of visible light LED is in the range of 405 to 421 nm, the illumination intensity is 4 mW/cmor more, and the irradiation energy is 7.5 J/cmor more, and an apparatus using said method is also provided.SELECTED DRAWING: None

Description

  The present invention relates to a method and an apparatus for suppressing the growth of microorganisms using visible light LEDs.

  As preservation techniques and distribution networks have developed, various foodstuffs have become widely available to consumers. However, microorganisms present in foods such as marine products, fruits and vegetables, and processed foods thereof grow over time, which leads to deterioration of food quality and, consequently, putrefaction. Therefore, it is important to suppress the growth of microorganisms.

  As a method for suppressing the growth of microorganisms, conventionally, various means such as heat treatment, pressure treatment, ultraviolet irradiation, and washing with ozone water or a sodium chlorite solution are known. For example, it is conventionally known that sodium chlorite solution can be used for washing raw vegetables, and even today, a new method (e.g., containing ultrafine bubbles containing ultrafine bubbles) using a sodium hypochlorite solution is more convenient. A method using a weakly alkaline stable sodium hypochlorite solution, Patent Document 1) has been reported.

JP 2018-102174 A

  An object of the present invention is to provide a method and an apparatus that can effectively suppress the growth of microorganisms.

The present inventor has conducted intensive studies in view of the above problems, and found that the peak wavelength of a visible light LED (light emitting diode) is in the range of 405 to 421 nm, the illuminance is 4 mW / cm ² or more, and the irradiation energy is 7.5 J /. It has been found that the growth of microorganisms can be effectively suppressed by irradiating a target object with visible light using a visible light LED as a light source so as to have a cm ² or more. The present invention has been completed as a result of further studies based on the findings, and is as follows. Item 1. Including a step of irradiating the target with visible light using a visible light LED as a light source, a method for suppressing the growth of microorganisms in the target, wherein the irradiation has a peak wavelength of the visible light LED in the range of 405 to 421 nm, A method characterized in that the irradiance is 4 mW / cm ² or more and the irradiation energy is 7.5 J / cm ² or more.
Item 2. Item ^2. The method according to Item 1, wherein the illuminance is 4 to 500 mW / cm ² .
Item 3. Item 3. The method according to Item 1 or 2, wherein the irradiation energy is 7.5 to 500 J / cm ² . Item 4. Item 4. The method according to any one of Items 1 to 3, wherein the irradiation time is 1 to 60 minutes.
Item 5. Item 5. The method according to any one of Items 1 to 4, wherein the object is at least one selected from the group consisting of marine products, agricultural products, livestock products, and processed products thereof.
Item 6. Item 6. The method according to any one of Items 1 to 5, further comprising a step of irradiating the object with ultraviolet light or visible light having a peak wavelength in a range from 265 nm to less than 405 nm.
Item 7. Item 7. The method according to any one of Items 1 to 6, further comprising a step of contacting the object with a compound represented by the following general formula (1):
(Wherein, R ₁ represents a linear or branched alkyl group having 1 to 4 carbon atoms, and R ₂ represents a hydrogen atom, a halogen atom, or a linear or branched alkoxy group having 1 to 4 carbon atoms. R ₃ represents a direct bond, a linear alkylene group having 1 to 12 carbon atoms, a linear alkenylene group having 2 to 12 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms. Alternatively, it represents a linear alkynylene group having 2 to 12 carbon atoms, and R ₄ represents a hydrogen atom, a hydroxyl group, or a linear alkoxy group having 1 to 18 carbon atoms.
Here, a linear alkylene group having 1 to 12 carbon atoms represented by R ₃ , a linear alkenylene group having 2 to 12 carbon atoms and a linear alkynylene group having 2 to 12 carbon atoms, and a carbon atom represented by R ₄ On the linear alkoxy groups of formulas 1 to 18, each independently represents a halogen atom, a hydroxyl group, an amino group, a sulfo group, a nitro group, a cyano group, a keto group, an isocyanate group, an isothiocyanate group, a carbon number of 1 to 18. At least one group selected from the group consisting of 18 linear or branched alkyl groups, phenyl groups and cyclohexyl groups may be substituted. )
Item 8. A visible light irradiation device used to suppress the growth of microorganisms in an object, comprising: an irradiation unit that irradiates the object with visible light using a visible light LED as a light source, wherein the irradiation unit has a peak wavelength of 405. A visible light irradiation device that irradiates visible light so as to have an illuminance of 4 mW / cm ² or more and an irradiation energy of 7.5 J / cm ² or more.
Item 9. Item 9. The visible light irradiation device according to Item 8, further comprising a support unit that supports the object, wherein the irradiation unit is arranged to irradiate the object supported by the support unit with visible light. Item 10. Item 10. The visible light irradiation according to item 9, wherein the support unit is a conveyor that conveys the object, and the irradiation unit is arranged to irradiate the object conveyed by the conveyor with visible light. apparatus.
Item 11. Item 9. The supporting unit is a container that stores at least a part of the target object, and the irradiation unit is arranged to irradiate the target object stored in the container with visible light. 6. The visible light irradiation device according to item 5.
Item 12. Item 12. The visible light irradiation device according to any one of Items 8 to 11, wherein the irradiation unit further includes a light source that irradiates an object with ultraviolet light or visible light having a peak wavelength in a range from 265 nm to less than 405 nm.
Item 13. Item 13. The visible light irradiation device according to any one of Items 8 to 12, further comprising a contact portion for bringing a compound represented by the following general formula (1) into contact with an object:
(Wherein, R ₁ represents a linear or branched alkyl group having 1 to 4 carbon atoms, and R ₂ represents a hydrogen atom, a halogen atom, or a linear or branched alkoxy group having 1 to 4 carbon atoms. R ₃ represents a direct bond, a linear alkylene group having 1 to 12 carbon atoms, a linear alkenylene group having 2 to 12 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms. Alternatively, it represents a linear alkynylene group having 2 to 12 carbon atoms, and R ₄ represents a hydrogen atom, a hydroxyl group, or a linear alkoxy group having 1 to 18 carbon atoms.
Here, a linear alkylene group having 1 to 12 carbon atoms represented by R ₃ , a linear alkenylene group having 2 to 12 carbon atoms and a linear alkynylene group having 2 to 12 carbon atoms, and a carbon atom represented by R ₄ On the linear alkoxy groups of formulas 1 to 18, each independently represents a halogen atom, a hydroxyl group, an amino group, a sulfo group, a nitro group, a cyano group, a keto group, an isocyanate group, an isothiocyanate group, a carbon number of 1 to 18. At least one group selected from the group consisting of 18 linear or branched alkyl groups, phenyl groups and cyclohexyl groups may be substituted. )

  According to the method and apparatus of the present invention, the growth of microorganisms can be effectively suppressed.

FIG. 1 is a diagram showing a schematic configuration of a visible light irradiation device according to an embodiment of the present invention. FIG. 2 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 3 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 4 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 5 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 6 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 7 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 8 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 9 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 10 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 11 is a diagram showing a schematic configuration of a visible light irradiation device according to another embodiment of the present invention. FIG. 12 is a photograph taken from above of a state in which the pot-fried whitebait is spread on a petri dish. FIG. 13 is a diagram showing the results of LED irradiation at a peak wavelength of 405 nm or 465 nm. FIG. 14 shows the results of LED irradiation at peak wavelengths of 405 nm, 412 nm, 421 nm, and 455 nm. FIG. 15 is a view showing the results of LED irradiation at an illuminance of 12.48 mW / cm ² or 1.71 mW / cm ² . FIG. 16 is a view showing an LED irradiation result at an illuminance of 12.48 mW / cm ² . FIG. 17 is a diagram showing the results of LED irradiation at an illuminance of 12.48 mW / cm ² . FIG. 18 shows the results of LED irradiation at an illuminance of 12.48 mW / cm ² . FIG. 19 shows the results of LED irradiation at an illuminance of 12.48 mW / cm ² . FIG. 20 is a diagram showing the results of LED irradiation on the crepe. FIG. 21 is a view showing a photograph of LED irradiation on the mini tomato spatula. FIG. 22 is a diagram showing the results of LED irradiation on the mini tomato spatula. FIG. 23 is a diagram showing the results of LED irradiation on the mini tomato spatula. FIG. 24 is a view showing a photograph of LED irradiation at an illuminance of 120.3 mW / cm ² . FIG. 25 is a diagram showing the results of LED irradiation at an illuminance of 120.3 mW / cm ² . FIG. 26 is a diagram showing the results of LED irradiation at an illuminance of 120.3 mW / cm ² . FIG. 27 is a diagram showing the results of LED irradiation at an illuminance of 10 mW / cm ² . FIG. 28 is a diagram showing the results of LED irradiation at an illuminance of 208 mW / cm ² . FIG. 29 is a diagram showing a taste test result. FIG. 30 is a diagram showing a taste test result. FIG. 31 is a diagram showing the results of using the compound and LED irradiation together. FIG. 32 is a view showing the result of using a compound and not performing LED irradiation. FIG. 33 is a view showing the results of the combined use of the compound and LED irradiation. FIG. 34 is a view showing a result of using a compound and not performing LED irradiation.

The present invention comprises a step of irradiating the object with visible light using a visible light LED as a light source, wherein the irradiation has a peak wavelength of the visible light LED in a range of 405 to 421 nm, Provided is a method for suppressing the growth of microorganisms in an object, which is performed so that the illuminance is 4 mW / cm ² or more and the irradiation energy is 7.5 J / cm ² or more.

  In the present invention, examples of the target object include marine products, agricultural crops, livestock products, processed foods thereof, nutrient solutions used for hydroponics, and the like. Regardless of whether the target object is edible (edible portion) or non-edible (non-edible portion), the growth of microorganisms is likely to be a problem, and thus the target object is preferably edible. Further, as the edible object, for example, at least one selected from the following examples is preferably exemplified.

  Although not limited to the present invention, marine products and processed products thereof include fresh shirasu, fried white shirasu, dried shirasu (crepe), seaweed, laver, kelp, seafood (sashimi, etc.), and dried seafood overnight , Heated seafood (boiled rice, boiled octopus, etc.), fish meat dough products (kamaboko, chikuwa, etc.) and the like. As crops and their processed products, tomatoes, peppers, carrots, lettuce, mizuna, spinach, cabbage, leeks, potatoes, lotus root, garlic, spices, grapes, strawberries, sudachi, tangerines, peaches, pears, etc. were cut. Stuff, fried food and the like are exemplified. Examples of livestock products and processed products thereof include raw meat (including minced foods, including raw and non-raw foods), poultry eggs, dried meat products (dried meats and the like), meatballs, hamburgers, sausages, and the like.

  Further, the present invention is not limited thereto, and as the edible target, marine products, agricultural products, livestock products, processed foods thereof, and the like, which are preferably stored at 15 ° C. or lower, are exemplified, and more preferably −30 to 10 Examples include marine products, agricultural products, livestock products, processed foods thereof, and the like, which are preferably stored at ° C.

  In the present invention, visible light irradiation using a visible light LED as a light source may be performed using a known light source as long as the peak wavelength of the visible light LED is in the range of 405 to 421 nm.

  As long as the peak wavelength is in the range of 405 to 421 nm, the full width at half maximum of the spectrum is not limited, but the full width at half maximum is preferably between 380 and 455 nm, more preferably between 395 and 430 nm. Is exemplified.

In the irradiation, illuminance (irradiance) may if 4 mW / cm ² or more, preferably 4~500mW / cm ^2, more preferably 10~480mW / cm ^2, more preferably 10~280mW / cm ² is exemplified Is done. Here, the illuminance means the illuminance on the surface of the object.

  In the irradiation, the irradiation time is not limited, but is preferably 1 minute or more, more preferably 1 to 60 minutes, further preferably 1 to 50 minutes, particularly preferably 1 to 40 minutes, and still more preferably 1 to 30 minutes. Is exemplified.

In the irradiation, the irradiation energy may be 7.5 J / cm ² or more, preferably 7.5 to 500 J / cm ² , more preferably 15 to 433 J / cm ² , and still more preferably 22 to 433 J / cm ² . Particularly preferably, 45 to 217 J / cm ² is exemplified.

Here, the irradiation energy is obtained from the product of the illuminance (mW / cm ² ) on the surface of the object and the irradiation time (second). When the irradiation is performed from both the upper and lower sides of the object as in Example 2 described later, the irradiation energy of 7.5 J / cm ² or more in this specification is the irradiation energy calculated on the upper side and the irradiation energy calculated on the lower side. Is the sum of

In the method of the present invention, the LED may be irradiated from only one direction of the object as described above, may be irradiated from two or more directions, and is appropriately determined according to the size, thickness, etc. of the object. do it. More specifically, for example, the LED may be irradiated (installed) from the upper side of the object, may be irradiated from the lower side, may be irradiated from both the upper side and the lower side, and these side surfaces (the upper side) Irradiation may be performed from the side perpendicular to (lower side). Also, any combination of these may be used. As described above, when the irradiation is performed from both the upper and lower sides of the object, the “irradiation energy of 7.5 J / cm ² or more” is the sum of the irradiation energy calculated for the upper side and the irradiation energy calculated for the lower side. Means Similarly, for example, when the LED is illuminated (installed) from all sides of the object, up, down, left, right, front and back, the “irradiation energy of 7.5 J / cm ² or more” is defined as upper, lower, left, right, front (front) Side), and the sum of the irradiation energies calculated for each side on the rear side (sum of six side surfaces).

  The temperature at the time of irradiating the target with visible light is not limited, and may be any temperature such as a freezing temperature, a refrigeration temperature, and a temperature at the time of frying of a whitebait or the like. From the viewpoint of avoiding as much as possible and irradiating easily, it is exemplified that the process is preferably performed at a temperature of 28 ° C. or lower, more preferably at a temperature of -30 ° C. to 28 ° C. (ambient temperature). In addition, the temperature may be 0 to 25 ° C or 4 to 10 ° C, since the operation can be preferably performed in these ranges.

  The state of the object at the time of irradiation with visible light is not limited, and may be, for example, any state such as frozen, thawed, semi-thawed, refrigerated, heated, or a state in which these processes have not been performed. You may. Foods with relatively short expiration dates, such as marine products and processed foods, are often subjected to processing such as freezing, thawing, semi-thawing, refrigeration, and heating.In the present method, any of these processings is performed. Can also be applied to

  According to the present invention, by irradiating the object with visible light as described above, it is possible to suppress the growth of microorganisms in the object. Further, according to the present invention, the growth of microorganisms can be suppressed even when refrigeration, freezing, or thawing is performed after freezing after irradiation with visible light. In addition, it is often recommended to store at -30 to 15 ° C. such as refrigeration or freezing for an object in which the growth of microorganisms is liable to be a problem. The present invention can be preferably applied to an object that is likely to become unstable.

  As described above, in the present invention, the microorganism is not limited as long as its growth in the object is a problem, and examples thereof include bacteria, fungi such as mold and yeast.

  From this viewpoint, it can be said that the method of the present invention preferably further includes a step of holding the object at −30 to 15 ° C. In the method, the step of holding the object at −30 to 15 ° C. may be performed before the step of performing the visible light irradiation, or may be performed after the step of performing the visible light irradiation. , Both before and after.

  Further, in the method of the present invention, the LED irradiation may be performed in a state where the object is not wrapped at all, or may be performed in a state where a part or all of the object is wrapped or the like. When irradiating the packaged object, it is preferable from the viewpoint of better efficiency that the package or the like is a package having visible light transmittance. In addition, when the object is on a container such as a tray and the visible light transmittance of the container is poor, the irradiation is prevented by the tray or the like from irradiating the LED to the object from the viewpoint of better efficiency. It is preferable to perform from the direction which cannot be performed.

  Further, the method of the present invention may further include a step of irradiating the object with ultraviolet light or visible light having a peak wavelength in a range from 265 nm to less than 405 nm. Irradiation procedures or the like of ultraviolet or visible light having a peak wavelength in the range of 265 nm to less than 405 nm are not limited, and may be performed according to conventionally known procedures and the like. In the method of the present invention, the step may be performed before the step of performing the visible light irradiation (the LED irradiation), or may be performed after the step of performing the visible light irradiation. It may be performed simultaneously with the step of performing light irradiation, or may be performed by combining at least two of before, after, and simultaneously. Although not limited thereto, as one embodiment, for example, the step is performed before the step of performing the visible light irradiation, and after the step of performing the visible light irradiation, the above-described target is -30 to 15 A step of maintaining the temperature at ° C may be performed. As described above, in the method of the present invention, it does not matter before or after the execution of the step and the step of holding the object at −30 to 15 ° C.

  Further, the method of the present invention may further include a step of contacting the object with a compound represented by the following general formula (1).

(Wherein, R ₁ represents a linear or branched alkyl group having 1 to 4 carbon atoms, and R ₂ represents a hydrogen atom, a halogen atom, or a linear or branched alkoxy group having 1 to 4 carbon atoms. R ₃ represents a direct bond, a linear alkylene group having 1 to 12 carbon atoms, a linear alkenylene group having 2 to 12 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms. Alternatively, it represents a linear alkynylene group having 2 to 12 carbon atoms, and R ₄ represents a hydrogen atom, a hydroxyl group, or a linear alkoxy group having 1 to 18 carbon atoms.
Here, a linear alkylene group having 1 to 12 carbon atoms represented by R ₃ , a linear alkenylene group having 2 to 12 carbon atoms and a linear alkynylene group having 2 to 12 carbon atoms, and a carbon atom represented by R ₄ On the linear alkoxy groups of formulas 1 to 18, each independently represents a halogen atom, a hydroxyl group, an amino group, a sulfo group, a nitro group, a cyano group, a keto group, an isocyanate group, an isothiocyanate group, a carbon number of 1 to 18. At least one group selected from the group consisting of 18 linear or branched alkyl groups, phenyl groups and cyclohexyl groups may be substituted. )

As described above, R ₁ is not limited as long as it is a linear or branched alkyl group having 1 to 4 carbon atoms. Although not limiting the present invention, examples of the linear or branched alkyl group having 1 to 4 carbon atoms represented by R ₁ include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, and a sec. -Butyl group, isobutyl group and tert-butyl group.
Although not limiting the present invention, R ₁ is preferably a straight-chain or branched-chain alkyl group having 1 to 3 carbon atoms, more preferably a straight-chain or branched-chain alkyl group having 1 or 2 carbon atoms. And more preferably a methyl group.

R ₂ represents a hydrogen atom, a halogen atom, but are not limited as long as it is a linear or branched alkyl group having 1 to 4 carbon straight or branched alkoxy group or a C 1 to 4 carbon atoms.

Examples of the halogen atom represented by R ₂ include, but are not limited to, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

The linear or branched alkoxy group having 1 to 4 carbon atoms represented by R ₂ is not limited to the present invention, but may be a methyloxy group (methoxy group), an ethyloxy group (ethoxy group), or a propyloxy group. Isopropyloxy group, n-butyloxy group, sec-butyloxy group, isobutyloxy group and tert-butyloxy group.

The linear or branched alkyl group having 1 to 4 carbon atoms represented by R ₂ is not limited to the present invention, but may be a linear or branched alkyl group having 1 to 4 carbon atoms represented by R ₁ described above. It is explained similarly to the chain alkyl group.

R ₂ is not limited to the present invention, but is preferably a hydrogen atom, a linear or branched alkoxy group having 1 to 4 carbon atoms, and more preferably a hydrogen atom and a linear alkoxy group having 1 to 3 carbon atoms. Or a branched alkoxy group, more preferably a hydrogen atom, a linear or branched C1 or C2 alkoxy group, particularly preferably a hydrogen atom or a methoxy group.

R ₃ is not limited as long as it is a direct bond, a linear alkylene group having 1 to 12 carbon atoms, a linear alkenylene group having 2 to 12 carbon atoms, or a linear alkynylene group having 2 to 12 carbon atoms.

Examples of the linear alkylene group having 1 to 12 carbon atoms represented by R ₃ include, but are not limited to, a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, Examples include an octylene group, a nonylene group, a decylene group, an undecylene group, and a dodecylene group.

Examples of the linear alkenylene group having 2 to 12 carbon atoms represented by R ₃ include, but are not limited to, a vinylene group, a propenylene group, a butenylene group, a pentenylene group, and the like. In the linear alkenylene group having 3 to 12 carbon atoms, the position and the number of double bonds are not limited.

Examples of the straight-chain alkynylene group having 2 to 12 carbon atoms represented by R ₃ include, but are not limited to, an ethynylene group, a propynylene group, a butynylene group, and a pentynylene group. In the linear alkynylene group having 3 to 12 carbon atoms, the position and the number of triple bonds are not limited.

R ₃ is not limited to the present invention, but is preferably a direct bond, a linear alkylene group having 1 to 12 carbon atoms, a linear alkenylene group having 2 to 12 carbon atoms, or a straight chain having 2 to 12 carbon atoms. Linear alkynylene group, more preferably a direct bond, a linear alkylene group having 1 to 6 carbon atoms, a linear alkenylene group having 2 to 6 carbon atoms, a linear alkynylene group having 2 to 6 carbon atoms, still more preferably Examples thereof include a direct bond, a linear alkenylene group having 2 to 4 carbon atoms, and a linear alkynylene group having 2 to 4 carbon atoms.

R ₄ is not limited as long as it is a hydrogen atom, a hydroxyl group, or a linear alkoxy group having 1 to 18 carbon atoms.

Examples of the linear alkoxy group having 1 to 18 carbon atoms represented by R ₄ include, but are not limited to, a methyloxy group (methoxy group), an ethyloxy group (ethoxy group), a propyloxy group, a butyloxy group, Examples include a pentyloxy group and a hexyloxy group.

R ₄ is not limited to the present invention, but is preferably a hydrogen atom, a hydroxyl group, a linear alkoxy group having 1 to 18 carbon atoms, more preferably a hydrogen atom, a hydroxyl group, and a linear alkoxy group having 1 to 12 carbon atoms. An alkoxy group, more preferably, a hydrogen atom, a hydroxyl group, a linear alkoxy group having 1 to 4 carbon atoms is exemplified.

Further, a straight-chain alkylene group having 1 to 12 carbon atoms represented by R _3, the number of carbon atoms represented by linear alkynylene group and R ₄ having 2 to 12 carbon linear alkenylene group and the carbon 2 to 12 carbon atoms A halogen atom, a hydroxyl group, an amino group, a sulfo group, a nitro group, a cyano group, a keto group, an isocyanate group, an isothiocyanate group, a carbon number of 1 to 18 At least one group selected from the group consisting of a linear or branched alkyl group, a phenyl group and a cyclohexyl group may be substituted.

  Here, the halogen atom is described in the same manner as described above. Examples of the linear or branched alkyl group having 1 to 18 carbon atoms include, but are not limited to, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, and a sec-butyl group. , Isobutyl group, tert-butyl group, n-octyl group, n-octadecyl group, 2-ethylhexadecyl group, 2-butyltetradecyl group, 2,3,4,5,6,7-hexamethyldodecyl group and the like Is exemplified.

The positions of HO—, R ₁ O—, and R ₂ — on the benzene ring of the compound represented by the general formula (1) are not limited. It only has to be present (substituted). Examples of the compound include, but are not limited to, the present invention, preferably a compound in which HO- is substituted at the 4-position on the benzene ring, and more preferably HO- is substituted at the 4-position and 3 and 5 are substituted. Compounds in which R ₁ O— and R ₂ — are each differently substituted are exemplified.

Although not limiting to the present invention, by way of example, in the general formula (1), the 4-position HO- is substituted, R ₁ O-it is substituted at the 3-position, R ₂ in the 5-position - is substituted , R ₁ is a methyl group, R ₂ is a hydrogen atom, R ₃ is a linear alkenylene group (vinylene group) having 2 carbon atoms, and a compound in which R ₄ is a hydroxyl group can be said to be ferulic acid. Further, the present invention is not limited thereto. For example, in the general formula (1), HO- is substituted at the 4-position, R ₁ O- is substituted at the 3-position, and R ₂ -is substituted at the 5-position. A compound in which R ₁ is a methyl group, R ₂ is a hydrogen atom, R ₃ is a direct bond, and R ₄ is a hydrogen atom can be said to be vanillin.

  The compound may be a commercially available product, or may be obtained by chemical synthesis according to a known procedure. Further, in the compound, any of stereoisomers such as geometric isomers and optical isomers may be used. Further, the compounds may be used alone or in combination of two or more.

  The step is not limited as long as the target can be brought into contact with the compound represented by the general formula (1). For example, these contacts are performed by mixing the compound represented by the general formula (1) with a solvent as necessary, and spraying, dripping, impregnating, or the like the obtained mixture on a part or the whole of an object. May be performed by immersing part or all of the object in the obtained mixture, and the number of spraying or immersion, the method, etc. are not limited and may be determined as appropriate. . The solvent may be any solvent such as water, glycerol, ethanol, dimethyl sulfoxide (DMSO), or any mixture of the solvents, and is not limited as long as the effects of the present invention can be obtained.

  Further, the present invention is not limited thereto. In these, for example, the compound is mixed with a nutrient solution used for nutrient solution cultivation (nutrition water, liquid fertilizer, culture solution, etc.), and the obtained mixture is mixed. It may be brought into contact with an object. The object is not limited and does not limit the present invention, but from the viewpoint that it can be easily contacted with the compound while performing nutrient solution cultivation, an object to be brought into contact with the nutrient solution mixed with the compound. Preferred examples of the product include roots of agricultural crops. When the compound is mixed with a nutrient solution or the like, it can be said that the compound is in contact with the nutrient solution or the like. Therefore, the nutrient solution or the like may be used as an object.

  The amount of the compound represented by the general formula (1) to be brought into contact with the object, the contact time, and the like are not limited, and may be appropriately determined depending on the type of the compound to be used, the object, and the like. Although the present invention is not limited thereto, examples include contacting the compound with a molar concentration of 0.1 to 50 mM with an object, more preferably 0.5 to 25 mM, and still more preferably 1 to 15 mM. Contacting the compound with an object.

  The contacting step may be performed, for example, before the step of irradiating the LED, or may be performed simultaneously with the step of irradiating the LED, regardless of the order, and before, simultaneously and after. May be implemented in combination. It is not limited as long as the compound is in contact with the object at the time of the LED irradiation. From this viewpoint, as a preferred embodiment, for example, the contacting step is a step of performing the LED irradiation. Before and / or simultaneously with the step of performing the LED irradiation.

  The state of the object at the time of contact is not limited as described above, and may be, for example, any state such as frozen, thawed, semi-thawed, refrigerated, and heated, and these treatments are not performed at all. There may be no state. For this reason, in the method of the present invention, for example, before and after the execution of the contacting step and the step of holding the aforementioned object at −30 to 15 ° C. The contact may be performed before or after the target object such as a crop is harvested, for example, and is not limited.

  The method of the present invention may further include a step of washing the object after the contacting step in order to remove the compound represented by the general formula (1) from the object. The washing step is not limited as long as the object can be washed, and is preferably performed with potable water, sterilized seawater, artificial seawater using potable water, or a liquid having the same quality as these. Can be illustrated.

  Further, the method of the present invention may include the contacting step and a step of irradiating ultraviolet light or visible light having the above-mentioned peak wavelength in the range of 265 nm to less than 405 nm (ultraviolet / visible light irradiation step). Also in this case, the contacting step may be performed before the ultraviolet / visible light irradiation step, or may be performed after the ultraviolet / visible light irradiation step. It may be performed at the same time, or may be performed by combining at least two of before, after, and simultaneously.

  For this reason, when the three steps of the contacting step, the step of irradiating the LED, and the step of irradiating the ultraviolet / visible light ray are used in combination, the order of these steps is not limited and may be determined as appropriate. Although the present invention is not limited thereto, as one embodiment, the ultraviolet / visible light irradiation step, the contact step, and the LED irradiation step may be performed in this order. As another embodiment, the contact step may be performed. The step of irradiating the LED and the step of irradiating ultraviolet / visible light may be performed in this order. For example, in these, the contacting step and the step of irradiating the LED may be performed simultaneously.

  According to the method of the present invention, it is possible to effectively suppress the growth of microorganisms in an object. Further, according to the method of the present invention, the use of the ultraviolet / visible light irradiation step and / or the contact step can also effectively suppress the growth of microorganisms in the object. In particular, as shown in Examples described later, according to the method of the present invention, by using the contacting step together, among microorganisms such as bacteria and fungi, the growth of fungi such as yeasts and molds can be effectively suppressed. be able to.

Visible light irradiating device The present invention provides a visible light irradiating device used for suppressing the growth of microorganisms in an object. The visible light irradiating apparatus of the present invention includes an irradiating unit that irradiates a visible light to a target using a visible light LED as a light source, and the irradiating unit has a peak wavelength in a range of 405 to 421 nm and an illuminance of 4 mW / cm ^2. As described above, irradiation is performed with visible light having an irradiation energy of 7.5 J / cm ² or more. The irradiation and the like are described in the same manner as described above.

  The visible light irradiation device includes, for example, a support unit that supports the object, and the irradiation unit is arranged so as to emit visible light to the object supported by the support unit. Can be configured as a device integrated in advance. As the device, for example, a device in which an irradiation unit is integrated with a conveyor that conveys an object as a support unit, a device in which an irradiation unit is integrated with a container that accommodates at least a part of the object as a support unit, and the like Can be exemplified. Examples of the container include a refrigerator, a freezer, a container, a storage, a storage, a warehouse, a container, a water tank, a pot, and the like.

  As an apparatus in which the irradiation unit is integrated with the conveyor, for example, as shown in FIGS. 1 and 2, the irradiation unit 1 is configured to irradiate the object 2 conveyed by the conveyor 3 with visible light L from above. Is installed. The upper side with respect to the target object 2 may be directly above as shown in FIG. 1 or may be obliquely above as shown in FIG. In FIG. 1, by arranging the irradiation unit 1 so as to cover the conveyor 3, it is possible to uniformly irradiate the visible light L to the entire object 2 conveyed by the conveyor 3. In FIG. 2, the irradiating unit 1 is installed so that the visible light L is emitted toward the center on both side edges in the width direction of the conveyor 3, and the visible light is also directed toward the center on the width direction of the conveyor 3. By arranging the irradiating unit 1 so as to irradiate L, the entirety of the object 2 conveyed by the conveyor 3 can be uniformly irradiated with the visible light L.

  Further, the irradiating unit 1 may be installed so that the visible light L is emitted from below (the side of the conveying surface 30 that comes into contact with the object 2) onto the object 2 conveyed by the conveyor 3. The lower side of the target object 2 may be directly below or may be obliquely below. The irradiation unit 1 may be provided on the transport surface 30 of the conveyor 3, or may be provided below the transport surface 30 when the transport surface 30 has light transmittance.

  In addition, the conveyor 3 may convey not only the object 2 in a horizontal direction but also the object 3 in a diagonal direction. The conveyors 3 may be arranged in multiple stages vertically, and may convey the object 2 continuously downward or upward. As the type of the conveyor 3, various configurations such as a belt conveyor, a slat conveyor, a roller conveyor, and a chain conveyor may be used. The conveyor 3 may be placed in a normal temperature environment, a refrigerated environment, or a frozen environment.

  Next, as an apparatus in which the irradiation unit is integrated with a refrigerator or a freezer for refrigerated or frozen storage of an object, for example, as shown in FIG. 3, the object 2 placed on a shelf 40 in the refrigerator or the freezer 4 On the other hand, the irradiation unit 1 is installed so that the visible light L is irradiated from above. Specifically, the irradiation unit 1 is installed over the entire top surface of the refrigerator or freezer 4 or the lower surface of each shelf 40. Thus, the entirety of the object 2 stored in the refrigerator or the freezer 4 can be uniformly irradiated with the visible light L. In addition, in addition to or instead of the top surface in the refrigerator or freezer 4 or the lower surface of each shelf 40, the irradiation unit 1 may be installed on the side surface or the bottom surface in the refrigerator or freezer 4, or the upper surface of each shelf 40.

  Next, as an apparatus in which an irradiation unit is integrated with a container for transporting an object, for example, as shown in FIG. 4, a plurality of partitions 51 are provided in the container 5 to partition the internal space into a plurality of sections 50 in the left-right direction. Then, the irradiation unit 1 is installed on opposing side surfaces of two adjacent partitions 51. Thereby, the entirety of the target object 2 stored in each section 50 in the container 5 can be uniformly irradiated with the visible light L. In addition, in addition to or instead of the side surface of each partition 51, the irradiation unit 1 may be installed on the front and rear side surfaces, the bottom surface, and the top surface in the container 5.

  Next, as a device in which the irradiation unit is integrated with the container for storing the object, although not shown, the inner surface of at least one of the bottom wall and the front, rear, left, and right side walls, preferably the front, rear, left, and right side walls The irradiation unit 1 is installed on the inner surfaces of two opposing walls. The ceiling of the container may be open or closed by a lid. The irradiation unit 1 may be provided on the inner surface of the lid. By placing the device in which the irradiation unit 1 is installed in a container capable of storing the target object 2 in a refrigerator or a freezer in a state where the target object 2 is stored in the container, the growth of microorganisms by irradiation with visible light L is performed. It is also possible to prevent a decrease in the freshness of the target object 2 while suppressing it. If the container has translucency such as transparency, the irradiation unit 1 may be provided on each wall of the container or on the outer surface of the lid.

  The irradiation unit can be integrated with other containers such as a storage, a storage, a warehouse, a water tank, and a pot similarly to the refrigerator, the freezer, the container, and the container. It should be noted that the above-described apparatus in which the irradiation unit and the support unit are integrated is merely an example, and various configurations may be used as long as the irradiation unit is installed so as to irradiate an object supported by the support unit with visible light. Stuff is included.

  The visible light irradiator does not have a supporting part, and has an existing conveyor for transporting objects, an existing refrigerator or freezer for refrigerated or frozen storage of objects, an existing container for transporting objects, and an existing container for storing objects. The irradiation unit may be configured to be installed in a container or the like. For example, as shown in FIG. 5, a moving table 6 in which the irradiation unit 1 is attached to the lower surface of the top plate unit 60 can be exemplified. The top plate 60 is supported by a plurality of legs 61, and the movable table 6 can be moved by attaching wheels 62 to the lower ends of the legs 61. The moving table 6 is arranged so that, for example, a table for placing the object 2 or a conveyor for transporting the object 2 is located in a space below the top plate 60, and the irradiation unit 1 on the lower surface of the top plate 60. By irradiating the object 2 with the visible light L, the entire object 2 can be uniformly irradiated with the visible light L.

  Further, as shown in FIG. 6, for example, a throw-in type irradiator 8 in which the irradiation unit 1 is sealed in a transparent container 80 made of glass or plastic can be exemplified. It is possible to irradiate the visible light L to the object 2 being fried by putting the object 2 such as irradiating the irradiator 8 into the boiler 9. In this case, the transparent container 80 can transmit the visible light L.

  The above-described visible light irradiation device may further include a contact portion for bringing the compound represented by the general formula (1) into contact with the object. The contact portion is not limited as long as the object can be brought into contact with the compound. For example, the contact portion may spray (spray), drip, impregnate, or the like, a mixture obtained by mixing the compound with a solvent, if necessary, on a part or all of the target object. A part or all of the target object may be immersed or the like, and the number of times of spraying or immersion, the method, and the like are not limited. The solvent may be any solvent such as water, glycerol, ethanol, dimethyl sulfoxide (DMSO), or any mixture of the solvents, and is not limited as long as the effects of the present invention can be obtained.

  The amount of the compound, the contact time, and the like are not limited, and may be appropriately determined depending on the type of the compound to be used, the object, and the like. Although the present invention is not limited thereto, examples include contacting the compound with a molar concentration of 0.1 to 50 mM with an object, more preferably 0.5 to 25 mM, and still more preferably 1 to 15 mM. Contacting the compound with an object.

  The contact between the object and the compound by the contact unit may be performed before the visible light irradiation (LED irradiation) on the object by the irradiation unit 1 or may be performed simultaneously with the LED irradiation, The order is not limited, and at least two of before, simultaneous, and after may be performed in combination. Although not limited thereto, it is preferable that the compound is in contact with the object at the time of the LED irradiation, and from this viewpoint, the contact between the object and the compound is performed before the LED irradiation on the object. And / or simultaneously.

  For example, as shown in FIG. 7, the contact portion is located on the upstream side with respect to the transport direction of the object 2 from the irradiation unit 1 that irradiates the object 2 conveyed by the conveyor 3 with visible light L from above. 7 is installed. In the present embodiment, the contact unit 7 is a spray device 70 that sprays the droplet D of the mixture M obtained by mixing the compound with the solvent onto the object 2 from above. The size of the droplet D of the mixture M is not particularly limited. The upper side with respect to the target object 2 may be directly above or may be obliquely above. Thus, the object 2 can be brought into contact with the compound before the object 2 is irradiated with the LED.

  Although not shown, the irradiating unit 1 is installed so that the object 2 conveyed by the conveyor 3 is irradiated with visible light L from below, and the contact unit 7 (spraying device 70) is mixed with the mixture. May be installed so as to spray the droplet of the liquid onto the object from above. Although not shown, the irradiating unit 1 is installed so that the object 2 conveyed by the conveyor 3 is irradiated with visible light L from above, and the contact unit 7 (spraying device 70) is The droplets may be set so as to be sprayed onto the target from above. Thereby, the object can be brought into contact with the compound at the same time that the object is irradiated with the LED.

  As shown in FIG. 8, the contact portion 7 may be a water tank 71 for storing the mixture, and after immersing at least a part of the object 2 in the mixture M in the water tank 71 for a predetermined time, manually or The object 2 may be automatically taken out of the water tank 71 and transported by the conveyor 3. Thus, the object 2 can be brought into contact with the compound before the object 2 is irradiated with the LED. The object 2 after at least a part of the object M is immersed in the mixture M for a predetermined time is taken out of the water tank 71 manually or automatically, and a refrigerator, a freezer, a container, a storage, a storage, and a storage provided with the irradiation unit 1 are provided. , A container or a kettle.

  In addition, as shown in FIG. 9, the irradiation unit 1 may be installed on the bottom wall of the water tank 71 and at least one of the front, rear, left and right side walls. The ceiling of the water tank 71 may be open, may be closed by a lid, or the irradiation unit 1 may be installed on the inner surface of the lid. In a state where the mixture M is stored in the water tank 71, at least a part of the object 2 is immersed in the mixture M, so that the object 2 is irradiated with the LED and at the same time, the object 2 is brought into contact with the compound. it can. The irradiating unit 1 is installed on the inner surface of the water tank 71 in a state of being housed in a case having translucency such as transparency. If the water tank 71 has translucency such as transparency, the irradiation unit 1 may be installed on the outer surface of each wall or lid of the water tank 71. Although not shown, the irradiation unit 1 may be provided around the water tank 71 and the object 2 in the water tank 71 may be irradiated with the LED from outside the water tank 71.

  The compound may be mixed with, for example, a nutrient solution (nutrition water, a liquid fertilizer, a culture solution, etc.) used for nutrient solution cultivation, and the resulting mixture may be brought into contact with an object. For example, as shown in FIG. 10, the object 2 may be irradiated with the LED from the irradiation unit 1 in a state where a part of the object 2 is immersed in a nutrient solution in which the compound is mixed in the cultivation container 72. In the present embodiment, the irradiation unit 1 is installed on an inner surface or an outer surface of at least one of the bottom wall of the cultivation container 72 and the front, rear, left and right side walls. The irradiation unit 1 is installed on the inner surface of the cultivation container 72 in a state of being housed in a case having translucency such as transparency. If the water tank 71 has translucency such as transparency, the irradiation unit 1 may be installed on the outer surface of each wall or lid of the water tank 71. Although not shown, the irradiating unit 1 may be provided around the cultivation container 72, and the object 2 in the cultivation container 72 may be irradiated with the LED from outside the cultivation container 72.

  As shown in FIG. 11, the visible light irradiating device may be integrally provided with the irradiating unit 1 and the spray device 70 as the contact unit 7. Thereby, when the target object 2 is a crop, for example, the contact with the compound and the LED irradiation can be performed simultaneously on the crop before harvesting. In FIG. 11, when the target object 2 is, for example, a crop, the crop may be a harvested crop.

  The state of the target object 2 at the time of contact with the compound is not limited, and may be, for example, any state such as frozen, thawed, semi-thawed, refrigerated, and heated, and these treatments are not performed at all. It may be in a state.

  The above-described visible light irradiation device may further include a cleaning unit that cleans the object in order to remove the compound that has come into contact with the object. Washing in the washing unit is not limited as long as the object can be washed, and may be performed with potable water, sterilized seawater, artificial seawater using potable water, or a liquid having the same quality as these. it can.

  In the above-described visible light irradiation device, the irradiation unit 1 includes, in addition to a light source (main light source) that emits visible light having a peak wavelength in a range of 405 to 421 nm, ultraviolet light or a peak wavelength in a range of 265 nm or more and less than 405 nm. A light source (auxiliary light source) that emits visible light may be further provided. The auxiliary light source emits ultraviolet light or visible light having a peak wavelength in the range of 265 nm to less than 405 nm before and / or after the visible light having a peak wavelength in the range of 405 to 421 nm is irradiated on the object 2. May be provided in the irradiation unit 1 so as to be irradiated. The auxiliary light source is provided in the irradiation unit 1 so that the target object 2 is irradiated with ultraviolet light or visible light having a peak wavelength in the range of 265 nm to less than 405 nm simultaneously with visible light having a peak wavelength in the range of 405 to 421 nm. It may be. For example, by alternately arranging the main light source and the auxiliary light source, or by arranging the main light source and the auxiliary light source to face each other with the object 2 interposed therebetween, it is possible to simultaneously irradiate the object 2 with light beams having different peak wavelengths.

  According to the visible light irradiation device of the present invention, the irradiation of the LED on the object can effectively suppress the growth of microorganisms in the object. Further, according to the visible light irradiation device of the present invention, the contact of the compound on the object, or by using the ultraviolet or visible light irradiation on the object in combination, effectively increases the growth of microorganisms in the object. Can be suppressed. In particular, as shown in Examples below, according to the visible light irradiation device of the present invention, by contacting the compound with the object, among microorganisms such as bacteria and fungi, particularly fungi such as yeast and mold. Proliferation can be effectively suppressed.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
Test example 1
Test procedure Approximately 1 g of commercially available Tokushima pot-fried Shirasu (frozen at −30 ° C. and thawed at 2.6 ° C. for 16 hours) was spread so as not to overlap a sterile plastic petri dish (53 mm in diameter). FIG. 12 shows a photograph taken from above of a state in which the pot-fried whitebait is spread on a petri dish.

The LED was irradiated in the incubator set at 25 ° C. The light source was a 405 nm peak wavelength LED (NCSU275T, manufactured by Nichia Corporation), and the light was emitted from two places below the petri dish. The distance from the light source to the whitebait was adjusted to 30 mm, and the illuminance (irradiance) on the surface of the whitebait (the lower surface (passing through the petri dish)) was set to 4.72 mW / cm ² . The illuminance is measured using a laser power / energy meter NOVA II (manufactured by OPPHIR), and measured at the center of the white ground (equal distance) between the two LEDs. be satisfactory illuminance value (peak irradiance of the lower surface) (IF = 0.5A). the irradiation time is 60 minutes, and the irradiation energy was 17 J / cm ^2. irradiation energy (J / cm ^2), the illuminance (mW / cm ² ) and the irradiation time (seconds).

After irradiating the LED, according to the viable cell count method according to the standard for food, additives, etc., the whitebait is transferred to a sterilized stomaching plastic bag (sterilized pack), and sterilized phosphate buffer solution (0.3 mM KH ₂ PO ₄ , pH 7.2) was added so as to be 10-fold diluted, and homogenized for 1.5 minutes. The obtained homogenized solution was serially diluted 10-fold with a sterilized phosphate buffer having the same composition, applied to a standard agar medium (manufactured by Nissui Pharmaceutical Co., Ltd.), cultured at 35 ° C. for 48 hours, and counted for colonies. The number of general bacteria was determined (this is immediately after irradiation). The number of general bacteria was determined in the same manner also for the shirasu without LED irradiation (this was designated as non-irradiation).

  In addition, the number of common bacteria was determined in the same manner for whitebait stored refrigerated at 2.6 ° C. for 48 hours after the LED irradiation. In addition, the number of general bacteria was determined in the same manner for the shirasu which had not been irradiated with the LED and was similarly refrigerated at 2.6 ° C. for 48 hours.

In addition, the number of general bacteria before and after storage was similarly determined for the fried potato radish that had been irradiated with the LED in the same manner as described above, except that a peak wavelength 465 nm LED (manufactured by Nichia Corporation) was used. However, the illuminance was 6.47 mW / cm ² and the irradiation energy was 23 J / cm ² .

  In addition, the main bacteria among 50 strains of general bacteria previously isolated from fried rice sardine using the same standard agar medium as described above are Psychrobacter sp. (Gram-negative bacteria, 19 strains) and Kocuria sp. (Gram-positive bacteria, 15 strains). Strain, Staphylococcus sp. (Gram-positive bacteria, 8 strains), and Macrococcus sp. (Gram-positive bacteria, 3 strains). In addition, there was no substantial increase in the temperature of whitebait due to LED irradiation, and it was not necessary to consider the effect of heating on the bacterial count.

Results The results are shown in FIG. As shown in FIG. 13, the number of colonies was reduced by 17% immediately after the irradiation with the LED having the peak wavelength of 405 nm as compared with the case without irradiation with the LED, and a bactericidal effect was observed. On the other hand, as shown in FIG. 13, when the LED having the peak wavelength of 465 nm was used, no decrease in the number of colonies was observed immediately after the LED irradiation, as compared with the case where the LED was not irradiated. Here, the 17% decrease in the number of colonies indicates the ratio of the number of colonies reduced by irradiation with the LED, when the number of colonies determined in the absence of LED irradiation is 100%.

  Although not shown in the figure, when an LED having a peak wavelength of 405 nm was used, the number of colonies in the LED-irradiated sample was reduced even after refrigeration for 48 hours, as compared with the case where no LED was irradiated. On the other hand, when the LED having the peak wavelength of 465 nm was used, the number of colonies after the refrigerated storage increased significantly when the LED irradiation was performed than when the LED was not irradiated.

Therefore, the peak wavelength of 405 nm, illuminance 4.72mW / cm ^2, 60 minutes irradiation time, whereas the growth of bacteria adhered to the food according to the LED irradiation at an irradiation energy 17 J / cm ² can be effectively suppressed It was found that a desirable growth inhibitory effect could not be obtained by LED irradiation at a peak wavelength of 465 nm, an illuminance of 6.47 mW / cm ² , an irradiation time of 60 minutes, and an irradiation energy of 23 J / cm ² .

Test example 2
Test procedure Approximately 1 g of pot fried whitebait obtained in the same manner as in Test Example 1 was weighed, spread in a sterilized petri dish in the same manner as described above, and irradiated with LED in an incubator set at 25 ° C. Using a 405 nm peak wavelength LED (NCSU275T, manufactured by Nichia Corporation) as the light source, adjust the distance from the light source to the shirasu and adjust the distance from the light source to the top and bottom of the petri dish (upper two places, lower two places, from the light source to the shirasu) (27.5 mm above, 28 mm below). The illuminance at the center between the two LEDs on the shirasu surface (upper and lower surfaces) was set to 12.48 mW / cm ² . The illuminance is measured on the surface of the shirasu in the same manner as described above using the above-described NOVA II, and means that the illuminance (peak illuminance) on one surface is 12.48 mW / cm ² . The irradiation time was 15 minutes and the irradiation energy was 22 J / cm ^{2 in} total. In the same manner as in Test Example 1, the number of general bacteria before and after refrigerated storage was determined for white radish with and without LED irradiation.

LED with a peak wavelength of 412nm (ILH-XC01-S410-SC211-WIR200, Intelligent LED Solutions Ltd., distance is upper 35mm, lower 36mm (0.2A)), LED with peak wavelength 421nm (3W 3535 420nm-430nm Star base, tiaochongyi, distance is upper 30mm, lower 31mm (0.3A)), LED with peak wavelength 455nm (LZ4-40B208-0000, LED Engin Inc., distance is upper 30mm, lower 31mm (34.7mA)) illuminance 12.48mW / cm ^2, irradiation time 15 min irradiation condition, the irradiation energy was carried out to determine the number of viable bacteria as a vertical sum 22J / cm ^2.

Results The results are shown in FIG. As shown in FIG. 14, the number of colonies decreased by 38 to 55% immediately after the irradiation of the LEDs with the peak wavelengths of 405 nm, 412 nm, and 421 nm, as compared to the case without the LED irradiation. In addition, after refrigerated storage, the number of colonies decreased by 55 to 88% due to LED irradiation as compared with the case without LED irradiation. In particular, the number of colonies after LED irradiation and storage was lower than the number of colonies without LED irradiation and before storage. From these facts, according to these LED irradiations, the growth of bacteria attached to food can be suppressed very effectively. In particular, according to these LED irradiations, bacteriostasis (no irradiation and storage (An effect lower than the previous number of bacteria).

  In contrast, when irradiating an LED with a peak wavelength of 455 nm, the number of colonies was reduced before and after storage, compared to no irradiation, but a desirable decrease in the number of colonies was not observed after storage (LED (Compared with non-irradiation, 12% decrease immediately after irradiation, 19% decrease after storage). From this, it was found that even if the illuminance, the irradiation time, and the irradiation energy were the same, the desired growth suppression effect could not be obtained when the peak wavelength was 455 nm.

Test example 3
Test procedure Approximately 1 g of pot fried shirasu obtained in the same manner as in Test Example 2 was spread on a sterile petri dish in the same manner as in Test Example 2, and irradiated with LEDs in an incubator set at 25 ° C. The number of general bacteria before and after storage was determined for the white radish.

In this test example, an illuminance of 12.48 mW / cm ² , irradiation for 15 minutes, and irradiation energy of 22 J / cm ² (total of upper and lower) were used in the same manner as in Test Example 2 using an LED having a peak wavelength of 421 nm. In this test example, the number of staphylococci was also determined in the same manner as in the measurement of the number of general bacteria except that a yolk-added mannitol salt medium (manufactured by Nissui Pharmaceutical Co., Ltd.) was used. (These are the conditions A).

Further, the condition A (illuminance 12.48mW / cm ^2, irradiation for 15 minutes, irradiation energy 22J / cm ²⁾ in place of the illuminance 1.71mW / cm ^2, irradiation 4 hours, the irradiation energy 24.6J / cm ² (dish upper 2 Condition B), irradiance 1.71 mW / cm ² , irradiation 2 hours, irradiation energy 24.6 J / cm ² (total of top and bottom, irradiation from top and bottom of petri dish (upper 2 places, lower 2 places)) As the condition C, the number of general bacteria and the number of staphylococci were determined in the same manner as described above. In these, the illuminance means the upper surface and the lower surface peak illuminance, respectively, as described above, and the illuminance also means the peak illuminance in the following test examples.

Results The results are shown in FIG. As shown in FIG. 15, under the condition A, the number of colonies was reduced by 38% immediately after the LED irradiation, as compared with the case without the LED irradiation. In addition, even after storage, the number of colonies decreased during LED irradiation as compared to the case without LED irradiation. In particular, under condition A, the number of colonies after LED irradiation and storage was lower than the number of colonies without irradiation and before storage, that is, a bacteriostatic effect was observed. From this, it was found that, under the condition A, the growth of bacteria adhering to food could be significantly suppressed. Also, in this case, a similar tendency was observed in the number of bacteria of staphylococci. For example, even after storage, the number of colonies was reduced by 86% by LED irradiation as compared to non-LED irradiation. The number of colonies after LED irradiation and storage was lower than that before no irradiation and storage, and a bacteriostatic effect was obtained.

  On the other hand, under the conditions B and C, no remarkable growth inhibition as observed under the condition A was not observed. Since the irradiation energy was higher in the conditions B and C than in the condition A, it was found that the cell growth inhibitory effect was not dependent only on the irradiation energy.

Test example 4
In the same manner as Test Procedure Test Example 2, spread similarly sterile Petri dish kettle fried shirasu, obtained, performed 5, 10, 15, 30 min irradiation the peak wavelength of 405 nm LED, at an illuminance 12.48mW / cm ^2, generally The bacterial count was determined. The number of staphylococci was also determined in the same procedure as in Test Example 3. The irradiation energy is 5 minutes irradiation time is 7.5J / cm ^2, 10 minutes during the irradiation is 15 J / cm ^2, 15 minutes during the irradiation is 22J / cm ^2, 30 minutes during the irradiation is 45 J / cm ^2.

Results The results are shown in FIGS. FIG. 16 shows the number of bacteria immediately after LED irradiation (without refrigeration). FIG. 17 shows the bacterial count after LED irradiation and refrigerated storage. As shown in FIG. 16, both the number of general bacteria and the number of staphylococci were significantly reduced by LED irradiation as compared with the case without LED irradiation. In particular, more effective growth suppression was observed by irradiation for 10 minutes or more. Thus, a sterilizing effect was obtained by the irradiation. Further, as shown in FIG. 17, even after storage, the number of general bacteria and the number of staphylococci were reduced by irradiation with LED, and more remarkable growth inhibitory effect (bacteriostatic effect) by irradiation for 10 minutes or more. Was observed.

Test example 5
Test procedure In the same manner as in Test Example 2, the obtained pot-fried whitebait was spread on a petri dish, the peak wavelength was 405 nm, the illuminance was 12.48 mW / cm ² , the irradiation was 15 minutes, and the irradiation energy was 22 J / cm ² (upper and lower) at 25 ° C. The LED was irradiated in the incubator set at (1). Then, the irradiated whitebait was stored at -30 ° C for 3 days, and then thawed at 2.6 ° C for 16 hours (measurement 2). After the thawing, it was further stored at 2.6 ° C. for 48 hours (measurement 3). After irradiation or storage, the numbers of general bacteria and staphylococci were measured in the same manner as described above (measurement 1 to 3). These results are shown in FIG.

  Approximately 1 g of fried rice in a pot at -30 ° C in a frozen state was spread in the sterilized petri dish so as not to overlap. In an incubator set at 10 ° C., irradiate the LED in the same manner as in Test Example 2, store at 2.6 ° C. for 48 hours, determine the number of general bacteria, and further determine the number of staphylococci as in Test Example 3. did. In this case, when the LED irradiation was completed, the surface of the whitebait was thawed, but the inside of the whitebait was frozen. The result is shown in FIG.

Results As shown in FIG. 18, in all of Measurements 1 to 3, a decrease in the number of bacteria was observed in LED irradiation compared to no LED irradiation. From this, it was found that even when freezing and thawing were involved after LED irradiation, bacterial growth could be suppressed by the LED irradiation. In particular, the number of bacteria of the LED irradiation in Measurements 2 and 3 is equal to or less than the number of unirradiated bacteria in Measurement 1, and even when freezing and thawing is performed after LED irradiation, the number of bacteria is equivalent to that of bacteriostatic. It was found that an excellent growth inhibitory effect was obtained.

  Further, as shown in FIG. 19, even with the LED irradiation during the thawing step, a decrease in the number of bacteria was observed as compared with the case without LED irradiation, and in this case also, a more remarkable growth inhibitory effect (bacteriostatic effect). Was observed.

Test example 6
Test procedure LED irradiation was carried out in the same manner as in Test Example 2, except that commercially available crimson from Tokushima Prefecture was used. Incidentally, each of the upper LED is the distance from the light source to the crepe 27.5 mm, and adjusted to each lower LED 28mm, illuminance 12.48mW / cm ² on one side surface, irradiation time 15 min, irradiation energy 22J / cm ² (upper and lower total ). After irradiation, refrigerated storage was performed at 3 ° C. for a long time (10 days, corresponding to the expiration date of the ramen used in this test), and the numbers of general bacteria and staphylococci were determined in the same manner as described above. For non-irradiated seaweed, the number of bacteria was determined in the same manner.

Results The results are shown in FIG. As is clear from FIG. 20, a remarkable growth inhibitory effect by LED irradiation was obtained even for crepe having a lower moisture content than fried shirasu. In particular, although the number of bacteria easily proliferated during refrigerated storage for 10 days corresponding to the expiration date, the number of bacteria could be reduced by 90% or more by LED irradiation.

Test example 7
Test Procedure A commercially available sashimi seaweed (boiled) was cut into a square shape (about 0.5 g), placed in the center of a sterile plastic petri dish having a diameter of 53 mm, and placed in an incubator set at 25 ° C. in the same manner as in Test Example 6 above. LED irradiation was performed. In the same manner as in Test Example 6, the illuminance on one surface was 12.48 mW / cm ² , the irradiation time was 15 minutes, and the irradiation energy was 22 J / cm ² (upper and lower).

  After irradiation with the LED, the wakame was transferred to a sterile pack, and the number of general bacteria and the number of staphylococci were determined in the same manner as described above. After LED irradiation, the cells were stored at 2.6 ° C. for 2 days (expiration date of sashimi seaweed) or for 4 days, and the numbers of general bacteria and staphylococci were similarly determined. For non-irradiated seaweed, the number of bacteria was determined in the same manner.

Results As a result, in both the number of general bacteria and the number of staphylococci, the increase in the number of bacteria was observed in both cold storage for 2 days and cold storage for 4 days without LED irradiation. A decrease in the number of bacteria was observed in both storage and refrigerated storage for 4 days. From this, it was possible to suppress the growth of bacteria in the seaweed by LED irradiation.

Test Example 8
Procedure of test
Cut off about 1 g of the belly part of a commercially available overnight dried cabbage (open) thawed at 3 ° C for 16 hours with a scalpel (about 12.5 mm square, 6.3 to 6.9 mm thick), and the center of a sterile plastic petri dish with a diameter of 53 mm And irradiating the LED in the incubator set at 10 ° C. in the same manner as in Test Example 6. Using a 405 nm peak wavelength LED (NVSU333AE, manufactured by Nichia Corporation) as the light source, adjust the distance from the light source to the camas to 29.5 mm for the upper LED and 30 mm for the lower LED (IF = 3.01 A), The illuminance on one surface was 120.3 mW / cm ² , the irradiation time was 15 minutes, and the irradiation energy was 217 J / cm ² (upper and lower).

  After irradiating the LED, the camas were transferred to a sterile pack, and the number of general bacteria was determined in the same manner as described above. In addition, the number of general bacteria was determined in the same manner for camas stored at 2.6 ° C. for a long time (6 days, expiration date of dried cabbage overnight) after LED irradiation. The number of bacteria was determined in the same manner also for camas without LED irradiation. The number of bacteria was determined in the same manner for non-irradiated camas.

Results The results are shown in Table 1. In Table 1, each value indicates the number of bacteria after storage for a long time (6 days) (number of bacteria after storage) in each of the LED non-irradiated camas (without LED irradiation) and the LED irradiated camas (with LED irradiation) before storage And the change (ratio) of the number of bacteria after storage for a long time. The test was performed three times. In the table, Calculations 1 to 3 are results without LED irradiation, and Calculations 4 to 6 are results with LED irradiation. As is clear from Table 1, by irradiating the LED, an increase in the number of bacteria due to long-term storage was significantly suppressed as compared with the case where the LED was not irradiated. Although camas are thicker than whitebait and the like, it has been found that bacterial growth can be significantly suppressed by irradiation with LEDs even for foods having such a thickness.

Test example 9
Test Procedure A commercially available mini tomato was immersed in a sodium hypochlorite solution (effective chlorine concentration: 1%) for 15 minutes, washed twice with sterilized water, and then dried at the bottom. The dried fly part was immersed twice in 10 mL of a bacterial solution of Acinetobacter baumannii (10 ⁵ cells / mL) and dried. A. baumannii was isolated from the grouper of open-field cultivated tomatoes and identified from the 16S rDNA sequence. A. baumannii was used as a representative gram-negative bacterium attached to crops.

In the incubator set at 10 ° C., LED irradiation was performed from two obliquely upward positions of the tomato with the stake facing up (FIG. 21). Using a 405nm LED (NVSU333AE, manufactured by Nichia Corporation) as the light source, adjust the distance from the light source to the left LED to 29.5mm and the right LED to 30mm. At an angle of 90 degrees to cross each other from above, and the illuminance was 120.3 mW / cm ² (however, the illuminance per LED, the surface of the letter, measured using the above-mentioned NOVA II, IF = 3.01 A) did. The irradiation time was 15 minutes, and the irradiation energy was 217 J / cm ² (total in both directions).

  Collect the non-irradiated and LED-irradiated mini tomato stalks with tweezers, put them in a sterile stomaching plastic bag, weigh them, add a sterile phosphate buffer so as to make 10-fold dilution, homogenize for 1 minute, It was spread on an agar medium and cultured at 35 ° C. for 48 hours. Next, A. baumannii and general bacteria were distinguished from the colony morphology (color, shape), and the number of each colony was counted to determine the number of bacteria. The result is shown in FIG.

  In addition, a test was performed in the same manner as described above using mini tomatoes not treated with the sodium hypochlorite solution (without inoculation of A. baumannii). The result is shown in FIG.

Results As is evident from FIGS. 22 and 23, the growth of common bacteria, A. baumannii, and microorganisms attached to mini tomatoes could be suppressed by LED irradiation also on tomato scabs.

Test example 10
Test Procedure Approximately 1 g of pot fried shirasu obtained in the same manner as in Test Example 2 was spread on a sterilized petri dish in the same manner as in Test Example 2. The LED was irradiated in an incubator set at 10 ° C. An LED (NVSU333A (U405), manufactured by Nichia Corporation) having a peak wavelength of 405 nm was installed as a light source, one at each of the top and bottom, shifted 10 mm left and right from the center of the petri dish (FIG. 24). Shirasu surface illuminance of Shirasu surface 120.3mW / cm ² (top and bottom, respectively LED directly below (directly above), measured using NOVA II described above, IF = 3.01 A, the distance to the Shirasu from the light source for upward LED29.5Mm, lower And the irradiation energy was 72 J / cm ² (total for upper and lower) for 5 minutes. After irradiation, the number of general bacteria and the number of staphylococci were determined in the same manner as described above. In addition, the number of general bacteria and the number of staphylococci were determined for whitebait stored refrigerated at 2.6 ° C. for 48 hours after LED irradiation. The number of general bacteria and the number of staphylococci were determined in the same manner for the white radish without LED.

In addition, under the same illuminance, the test was performed with irradiation energy of 217 J / cm ² (total of upper and lower) for 15 minutes and irradiation energy of 433 J / cm ² (total of upper and lower) for 30 minutes. Were determined.

Results The results are shown in FIGS. In both FIGS. 25 and 26, a growth suppression effect by LED irradiation was obtained, and in particular, a more remarkable growth suppression effect of bacteriostasis was observed. However, the weight of the shirasu after irradiation for 30 minutes was reduced by 15% as compared with the shirasu before irradiation. For this reason, from the point of further reducing the risk of quality change, it was found that it is better to set the irradiation time to 30 minutes or less, particularly in the case of visible light LED irradiation at high illuminance such as 120.3 mW / cm ² . .

Test Example 11
Test Procedure The pot-fried whitebait obtained in the same manner as in Test Example 2 was spread on a sterile petri dish, and an illuminance of 10 mW / cm ² , irradiation for 15 minutes, and irradiation energy of 18 J / The LED was irradiated in an incubator set at 25 ° C. as cm ² (total of upper and lower sides), and the number of general bacteria and the number of staphylococci were determined as described above.
Results The results are shown in FIG. As shown in FIG. 27, a remarkable growth suppression effect by LED irradiation was obtained. In particular, a more remarkable growth inhibitory effect of bacteriostatic was observed.

Test Example 12
Test Procedure The pot-fried whitebait obtained in the same manner as in Test Example 10 was spread on a sterile petri dish, and a peak wavelength of 405 nm was used in the same manner as in Test Example 10, illuminance 208 mW / cm ² , irradiation for 1 minute, irradiation energy 25 J / The LED was irradiated in an incubator set at 10 ° C. as cm ² (total of upper and lower), and the number of general bacteria was determined as described above.
Results The results are shown in FIG. As shown in FIG. 28, a remarkable growth suppression effect by LED irradiation was obtained. In particular, a more remarkable growth inhibitory effect of bacteriostatic was observed.

Test Example 13
Test Procedure In the same manner as in Test Example 2, about 1 g of the obtained pot-fried whitebait was spread on a sterile petri dish. In the same manner as in Test Example 10, the LED was irradiated in an incubator set at 10 ° C. Specifically, as a light source, an LED (NVSU333A (U405), manufactured by Nichia Corporation) having a peak wavelength of 405 nm was placed one by one vertically above and below the center of the petri dish by 10 mm. Shirasu surface illuminance of Shirasu surface 120.3mW / cm ² (top and bottom, respectively LED directly below (directly above), measured using NOVA II described above, IF = 3.01 A, the distance to the Shirasu from the light source for upward LED29.5Mm, lower And the irradiation energy was 72 J / cm ² (total for upper and lower) for 5 minutes. After irradiation, the number of general bacteria and the number of staphylococci were determined in the same manner as described above. In addition, the number of general bacteria and the number of staphylococci were determined for shirasu refrigerated at 2.6 ° C. for 5 days and 7 days after LED irradiation. The number of general bacteria and the number of staphylococci were determined in the same manner for the white radish without LED.

Results As a result, on all of the third, fifth, and seventh days of storage, remarkable growth suppression of the number of bacteria was observed when irradiated with LED, as compared with the case without LED irradiation. The general viable cell count is the most representative index indicating the degree of microbial contamination of food, and is known as an index reflecting the state of microbial contamination. As a general criterion, the general bacterial count is less than 10 ⁵ CFU / g for cooked foods and less than 10 ⁶ CFU / g for unheated foods. In this test example, in the case of no LED irradiation, the expiration date had to be 2 days according to the standard because it exceeded 10 ⁵ CFU / g after 3 days of storage. In contrast, when the LED irradiation was performed, it was less than 10 ⁴ CFU / g even after 5 days of storage, and was less than 10 ⁵ CFU / g even after 7 days. Therefore, by the LED irradiation of this test example, the expiration date can be at least 7 days, that is, the expiration date can be extended from 2 days to 7 days as compared with the case of no irradiation.

Test Example 14
Table 2 below shows the change in the number of bacteria when a peak wavelength of 405 nm was used for some of the test examples. Although not shown in the test example, the results of determining the number of general bacteria in the same manner as in test example 2 except that the illuminance was 21.2 mW / cm ² , the irradiation time was 10 minutes, and the irradiation energy was 25 J / cm ² were also shown in the table. It is shown in FIG.

In Table 2, for example, the illuminance 12.48mW / cm ^2, shown in the column of the irradiation energy 7.5J / cm ² "16/34 (5 min)", the illuminance 12.48mW / cm ^2, irradiation energy 7.5J / cm ^2, When the LED is irradiated for 5 minutes, immediately after irradiation, the number of general bacteria decreases by 16% by LED irradiation compared to LED non-irradiation. This indicates that the number of general bacteria has been reduced by 34%. The shaded portion in Table 2 indicates that the bacteriostatic effect was obtained by LED irradiation even after refrigerated storage at 2.6 ° C. for 48 hours.

  As can be understood from Table 2, by setting the illuminance and irradiation energy within a certain range, it is possible to more effectively suppress the growth of bacteria, and in particular, remarkable sterilization immediately after irradiation and remarkable after refrigerated storage. It was found that an excellent bacterial growth inhibitory effect (bacteriostatic effect) was obtained.

Test Example 15
Test procedure In the same manner as in Test Example 2 above, the pot fried white sardine was spread on a sterile petri dish, and an ultraviolet LED (NCSU234AE, manufactured by Nichia Chemical Industry Co., Ltd.) having a peak wavelength of 280 nm in an incubator set at 25 ° C. was 800 mm × 600 mm. Irradiation was performed for 1 minute using a light source having 8 × 4 = 32 substrates. The irradiation was performed in one direction from above, and the irradiation distance was 10 mm. The illuminance was 11.1 mW / cm ² immediately below one LED, and the irradiation energy was 0.67 J / cm ² .

Next, irradiation was performed at a peak wavelength of 405 nm, an illuminance of 12.48 mW / cm ² , and an irradiation energy of 15 J / cm ² for 10 minutes as described in Test Example 2. Further, as another irradiation condition at the peak wavelength of 405 nm, irradiation was performed at an illuminance of 21.2 mW / cm ² for 10 minutes and an irradiation energy of 25 J / cm ² (the distance from the light source to the upper part was 19 mm on the upper side and 20 mm on the lower side. ).

  Immediately after the irradiation, the cells were refrigerated at 2.6 ° C. for 48 hours, and the numbers of general bacteria and staphylococci after storage were determined. In addition, the number of general bacteria and the number of staphylococci immediately after irradiation and after storage were determined for only UV LED irradiation and visible light LED irradiation.

Results As a result, by using the ultraviolet LED and the visible light LED together, a higher bacterial growth inhibitory effect was obtained as compared with the case of the ultraviolet LED irradiation alone or the case of the visible light LED irradiation alone. In particular, when the illuminance was 21.2 mW / cm ² and the irradiation energy was 25 J / cm ² , a synergistic effect of suppressing bacterial growth by combining with an ultraviolet LED was observed. Thus, it was found that irradiation with other wavelengths, including UV LED irradiation, could be used in combination with the visible LED irradiation.

Test Example 16
Test procedure In the same manner as in Test Example 10 above (the irradiation distance was 30.5 mm on the upper side, 31 mm on the lower side, and the illuminance was adjusted to 120.1 mW / cm ² on both the upper and lower sides), and the obtained pot-fried whitebait was spread on a sterile petri dish. In an incubator set at 10 ° C., a peak wavelength of 405 nm LED (NVSU333A (U405), manufactured by Nichia Corporation) was used as a light source at an illuminance of 120.1 mW / cm ^{2 for} 5 minutes with an irradiation energy of 72 J / cm 2. ^The LED was irradiated at an irradiation energy of 500 J / cm ² (total of upper and lower) for ² (upper and lower) or irradiation for 34.7 minutes.

  Next, the taste test of the pot-fried whitebait was performed using a taste recognition device (Insent Taste Sensing System, SA402B, manufactured by Intelligent Sensor Technology Co., Ltd.) according to the evaluation procedure of the device.

  In the test for 5 minutes of irradiation, (1) 0 days without irradiation, (2) immediately after irradiation, (3) 2 days after storage at 3 ° C without irradiation, (4) 2 days after storage at 3 ° C after irradiation, (5) 3 days without irradiation Five days after storage at 5 ° C., (6) 5 days after storage at 3 ° C. after irradiation, (7) 7 days after storage at 3 ° C. without irradiation, and (8) white rice after 7 days after storage at 3 ° C. after irradiation, were evaluated using 14 to 15 g, respectively. Transfer the pot-fried whitebait (1) to (8) to a sterile pack, add sterile ultrapure water to make a 10-fold dilution, homogenize for 1 to 2 minutes, and filter the supernatant with filter paper (FIRTER PAPER, glade2, ADVANTEC). Then, a filtrate of 70 mL or more was obtained. The obtained filtrate was stored frozen at -80 ° C, transferred to 2.6 ° C the day before the measurement, and completely thawed at 30 ° C on the day of the measurement.

  In the test for 34.7 minutes of irradiation, (1) 0 days without irradiation, and (2) 14 to 15 g of immediately after irradiation were used and treated and thawed in the same manner as described above.

The taste evaluation criteria by the taste recognition device are as follows. This follows the prescribed criteria of the device.
<Taste evaluation>
(1) The non-irradiated 0-day sample was set as the reference value 0, and the other samples (2) to (8) had a first taste (acidity, bitterness, astringency, astringency, umami, saltiness) and a finish (bitterness, astringency, Umami koku) was examined. The sourness can be excluded by -13, the saltyness can be excluded by -6, and the others can be excluded by negative values. In the case of pot-fried whitebait, the taste was evaluated by examining the saltiness, umami, bitterness, astringency, and umami richness. It is said that a human tongue can sense a change in taste of 1 or more (0.5 or more for taste professionals) by the device.

Results The results of the taste test for 5 minutes of irradiation are shown in FIG. 29 below. Since the change amount of 1 or more is considered to be detectable by the human tongue, it was found that the changes in salty taste, umami, bitter taste, astringency stimulus, and umami richness were at levels that could not be detected by the human tongue. Therefore, it was found that the irradiation treatment did not affect the taste quality even in refrigerated storage for one week.

The results of the taste test for 34.7 minutes of irradiation are shown in the following FIG. Treatment with high irradiation energy of 500 J / cm ² increased saltiness by 1.02. This change was remarkable when compared with the salty taste of the sample immediately after the 5-minute irradiation, but it was found that other taste changes were at levels that could not be detected by the human tongue. The increase in saltiness was thought to be due to a decrease in the water content of shirasu caused by LED radiant heat. Therefore, irradiation for a long time at 120 mW / cm ² can change the taste quality of fried whitebait, and from the viewpoint of suppressing taste change, it is better to set the irradiation time at the illuminance to less than 34.7 minutes. Was.

Test Example 17
Test Procedure A fungus (Cladosporium cladosporioides IFM63149 (mold)) was inoculated into a potato dextrose medium (PDA medium, manufactured by Nissui Pharmaceutical Co., Ltd.) and allowed to stand still at 25 ° C. for 14 days. After the culture, a 0.85% (w / v) aqueous sodium chloride solution containing 0.1% (w / v) Tween 80 was added to the medium, and the spores were scraped off with a conical rod. The mycelium was removed from the suspension thus obtained by using a sterilized gauze-containing chip, and the cells were collected by centrifugation at 6570 × g (3 minutes, 4 ° C.) and washed with a 0.8% aqueous sodium chloride solution. . The washing operation was performed twice. After resuspension in sterile water, the number of conidia is counted using a hemocytometer (manual blood cell counter, manufactured by Elma Sales Co., Ltd.), the concentration of the conidia suspension is calculated, and the suspension is diluted with sterile water. It was adjusted to 5 × 10 ⁶ conidia / mL.

  In this test example, ferulic acid, ferulic acid methyl ester, caffeic acid, coumaric acid, chlorogenic acid, vanillic acid, gallic acid, and vanillin were used as test compounds. Commercial products were used except for ferulic acid methyl ester (ferulic acid: trade name trans-ferulic acid, caffeic acid: trade name caffeic acid, coumaric acid: trade name trans-p-coumaric acid, vanillic acid: trade name vanillic acid, Gallic acid: trade name gallic acid hydrate, vanillin: trade name vanillin (all manufactured by Tokyo Chemical Industry Co., Ltd.), chlorogenic acid: trade name chlorogenic acid (product made by Sigma-Aldrich Japan)). Ferulic acid methyl ester was obtained by chemical synthesis as described below.

310 mg (1.596 mmol) of ferulic acid was dissolved in 7 mL of methanol, and 31.3 mg (0.2 eq.) Of concentrated sulfuric acid was added. The reaction was carried out by refluxing under a nitrogen stream. After the reaction for 4 hours, the solvent was removed by an evaporator, water was added, and the residue was washed by sonication. The mobile phase was purified as a mixed solvent of hexane and ethyl acetate using a silica gel column (Silica gel 120, spherical, 70-230 mesh, manufactured by Nacalai Tex Corporation). The purified product (colorless oil, 278 mg, yield 84%) was confirmed to be one component by thin layer chromatography (Silica gel 60 F254, manufactured by Merck KGaA), and ¹ H-NMR (CDCl ₃ ) spectrum analysis was performed. As a result, it was confirmed that the compound had the structure of the target compound (ferulic acid methyl ester).

¹ H NMR (400 MHz, CDCl ₃ , δin ppm): 3.73 (s, 3H, OCH ₃ ), 3.86 (s, 3H, COOCH ₃ ), 6.22 (d, 1H, J = 15.9 Hz, ethylene α-CH) , 6.85 (d, J = 8.2 Hz, 1H, 4-hydroxy-3-methoxyphenyl group 5-position-CH), 6.96 (s, 1H, 4hydroxy-3-methoxyphenyl group 2-position-CH), 7.01 (d, J = 8.2 Hz, 1H, 4-hydroxy-3-methoxyphenyl group 6-position-CH), 7.55 (d, 1H, J = 15.9 Hz, ethylene β-CH)

Note that, as an example, ferulic acid can be obtained by substituting HO— in the 4-position, R ₁ O— in the 3-position, R ₂ — in the 5-position, and R _{2 in the} general formula (1). ₁ is a methyl group, R ₂ is a hydrogen atom, R ₃ is a linear alkenylene group (vinylene group) having 2 carbon atoms, and R ₄ is a hydroxyl group.

Ferulic acid methyl ester, the general formula (1), the 4-position HO- is substituted, _R 1 O-is substituted at the 3-position, _{R 2} in the 5-position - is substituted, _{R 1} is a methyl group, R ₂ is a hydrogen atom, R ₃ is a straight-chain alkenylene group having 2 carbon atoms (vinylene group), and R ₄ is a straight-chain alkoxy group having 1 carbon atom (methoxy group).

Vanillic acid, in the general formula (1), 4-position HO- is substituted, _R 1 O-is substituted at the 3-position, _{R 2} in the 5-position - is substituted, _{R 1} is a methyl group, _{R 2} Is a hydrogen atom, R ₃ is a direct bond, and R ₄ is a hydroxyl group.

Vanillin, in the general formula (1), the 4-position HO- is substituted, _R 1 O-is substituted at the 3-position, _{R 2} in the 5-position - is substituted, _{R 1} is a methyl group, _{R 2} is A hydrogen atom, R ₃ is a direct bond, and R ₄ is a hydrogen atom.

  Each test compound was adjusted to a concentration 200 times the test concentration using 80% dimethyl sulfoxide (DMSO, Wako Special Grade, manufactured by Wako Pure Chemical Industries, Ltd.). The final concentration of DMSO in the bacterial solution in the test described below was 0.4%.

The bacterial suspension obtained as described above was diluted with sterile water and placed in a well of a 24-well plate (IWAKI) containing a stirrer (final concentration 5 × 10 ⁴ conidia / mL), and the test compound was added to the suspension. 2.5 mM or 3.0 mM was added to each well (total amount: 2.65 mL). Immediately for initial bacterial count measurement, 150 μL of bacterial solution was collected, and 1.35 mL of Sabouraud liquid medium containing 0.1% (w / v) Tween 80 (10 g of Bacto ^™ Peptone in 1 L (manufactured by BD), D (+)-glucose 40 g (manufactured by Wako Pure Chemical Industries, Ltd.). Then, in a incubator set at 25 ° C., while stirring the bacterial solution using a stirrer, one well was irradiated with LED from above using one LED downward. As a light source, a 405 nm peak wavelength LED (NVSU333A (U405), manufactured by Nichia Corporation) was installed at a distance of 38.0 mm above the bottom of the well of the 24-well plate. The illuminance at the irradiation distance was measured before the test, and was 84.6 mW / cm ² .

After irradiation for 60 minutes (irradiation energy: 305 J / cm ² ), 150 μL of the bacterial solution was collected from the well and diluted into 1.35 mL of Sabouraud liquid medium containing 0.1% (w / v) Tween 80. Further, this diluted solution was diluted with a 0.8% aqueous sodium chloride solution containing 0.1% (w / v) Tween 80 to prepare a 10-fold serial dilution series. 100 μL of each serial dilution was applied to a PDA medium and cultured at 25 ° C. for 3 days. After the culture, colony count was performed to calculate the number of viable bacteria. The test data is n = 3 and the results are the average of three experiments.

  In the above procedure, when the LED irradiation was performed in the same manner except that the test compound was not added (that is, the bacterial suspension diluted with sterile water was mixed with a 0.4% DMSO solution), the test compound was similarly added. However, when no LED irradiation was performed (dark place) and when the test compound was not added and LED irradiation was not performed (dark place), the test was also performed, and the viable cell count was calculated in the same manner.

Results In the above procedure, when the test compound was not added and the LED irradiation was not performed, the number of bacteria after 60 minutes was almost the same as the initial number of bacteria. On the other hand, when the LED irradiation was performed in the same manner except that the test compound was not added in the above procedure, the number of bacteria after 60 minutes was reduced by 53% compared to the number of initial bacteria. Thus, even when the test compound was not used, the LED irradiation could effectively suppress the growth of fungi as well as bacteria.

FIG. 31 shows the results of adding a test compound and performing LED irradiation in the above procedure (2.5 mM of the test compound added). In FIG. 31, FA indicates ferulic acid, VA indicates vanillic acid, Vani indicates vanillin, FAOMe indicates ferulic acid methyl ester, CaA indicates caffeic acid, GA indicates gallic acid, CA indicates coumaric acid, ChA indicates chlorogenic acid, and DMSO indicates test. The case where no compound is added is shown. Initial shows the initial number of bacteria, and 60 min shows the number of bacteria after 60 minutes of LED irradiation (irradiation energy of 305 J / cm ² ).

  As shown in FIG. 31, when CaA, GA, and ChA were used as test compounds, a decrease in the number of bacteria was observed, which was about the same or less as when no test compound was used (DMSO in the figure). For example, when GA was used, the number of bacteria after 60 minutes was reduced by only 51% as compared with the number of initial bacteria. In contrast, when FA, VA, Vani, and FAOMe were used as test compounds, a remarkable decrease in the number of bacteria was observed, and the number of bacteria 60 minutes later was FA, Vani, and FAOMe, compared to the initial number of bacteria. , And VA decreased by 94%. When CA was used as the test compound, a further decrease in the number of bacteria was observed than when CaA, GA, and ChA were used, but the number of bacteria after 60 minutes was 83% of the initial number of bacteria. It was a decrease. From this, it was confirmed that when FA, VA, Vani, and FAOMe were used as compounds, the growth of fungi could be remarkably suppressed.

  In addition, FIG. 32 shows the results of the procedure in which the test compound was similarly added but LED irradiation was not performed (the amount of the test compound added was 2.5 mM). As shown in FIG. 32, when the test compound was similarly added but LED irradiation was not performed, a significant decrease in the number of bacteria was not observed after 60 minutes regardless of the type of the test compound. It was almost the same as the case where no LED was added and no LED irradiation was performed (DMSO in FIG. 32). From this, it was found that the number of bacteria was not reduced only by bringing the test compound into contact with the microorganism. Further, from the results of FIGS. 31 and 32, the use of the LED irradiation in combination with the contact with FA, VA, Vani, and FAOMe resulted in a further remarkable decrease in the number of bacteria, and therefore, it was possible to significantly suppress the growth of microorganisms. confirmed.

Although not shown in the results, the same tendency was observed when the amount of the test compound added was 3.0 mM. For example, when both the contact with VA and the LED irradiation were used, 60 minutes later (irradiation energy) The bacterial count of 305 J / cm ² ) was reduced by 99% or more compared to the initial bacterial count. Although not shown in the results, the test was performed in the same manner as above except that the amount of FA added was 5.1 mM and the LED irradiation time was 20 minutes (irradiation energy: 102 J / cm ² ). The number of bacteria decreased by 99% or more as compared with the number of bacteria that started, and it was confirmed that the growth of microorganisms could be remarkably suppressed.

Test Example 18
Test Procedure A fungus (Candida albicans NBRC 1385 (yeast)) was inoculated with one platinum loop into Sabouraud's liquid medium and cultured with shaking at 28 ° C for 24 hours. After the culture, the cells were collected by centrifugation at 6570 × g (3 minutes, 4 ° C.), and washed with a 0.8% aqueous sodium chloride solution. The washing operation was performed twice. The collected bacteria are resuspended in 6 mL of sterile water, and the bacterial solution is measured with a spectrophotometer (OD = 660 nm), and the turbidity is adjusted so that OD ₆₆₀ = 0.158 (2 × 10 ⁶ cells / mL). It was adjusted.

  In this test example, ferulic acid, ferulic acid methyl ester, caffeic acid, coumaric acid, chlorogenic acid, vanillic acid, gallic acid, and vanillin were used as test compounds. These are the same compounds as in Test Example 17 described above, and each test compound was prepared at a concentration 200 times the test concentration using 80% dimethyl sulfoxide in the same manner as described above. The final concentration of DMSO in the bacterial solution in the test described below was 0.4%.

The bacterial suspension obtained as described above was diluted with sterile water, and placed in a well of a 24-well plate containing a stirrer (final concentration 2 × 10 ⁵ cells / mL), and the test compound was adjusted to 2.5 mM. Each well was added to each well (total amount: 2.65 mL). Immediately, for the measurement of the number of initial bacteria, 150 μL of the bacterial solution was collected and diluted with 1.35 mL of Sabouraud liquid medium containing 0.1% (w / v) Tween 80. Then, in a incubator set at 25 ° C., while stirring the bacterial solution using a stirrer, one well was irradiated with LED from above using one LED downward. The same LED as in Test Example 17 was used as a light source, and the LED was installed at a distance of 38.0 mm above the bottom of the well of the 24-well plate. The illuminance at the irradiation distance was measured before the test, and was 84.6 mW / cm ² .

After irradiation for 40 minutes (irradiation energy: 203 J / cm ² ), 150 μL of the bacterial solution was collected from the well and diluted into 1.35 mL of Sabouraud liquid medium containing 0.1% (w / v) Tween 80. Further, this diluted solution was diluted with a 0.8% aqueous sodium chloride solution containing 0.1% (w / v) Tween 80 to prepare a 10-fold serial dilution series. 100 μL of each serial dilution was applied to Sabouraud agar medium (manufactured by Nissui Pharmaceutical Co., Ltd.) and cultured at 28 ° C. for 3 days. After the culture, colony count was performed to calculate the number of viable bacteria. The test data is n = 3 and the results are the average of three experiments.

  In the above procedure, when the LED irradiation was performed in the same manner except that the test compound was not added (that is, the bacterial suspension diluted with sterile water was mixed with a 0.4% DMSO solution), the test compound was similarly added. However, when no LED irradiation was performed (dark place) and when the test compound was not added and LED irradiation was not performed (dark place), the test was also performed, and the viable cell count was calculated in the same manner.

Results In the above procedure, when the test compound was not added and LED irradiation was not performed, the number of bacteria after 40 minutes was almost the same as the initial number of bacteria. On the other hand, in the above procedure, when LED irradiation was performed in the same manner except that the test compound was not added, the number of bacteria after 40 minutes was reduced by 45% as compared with the number of initial bacteria. Thus, even when the test compound was not used, the LED irradiation could effectively suppress the growth of fungi as well as bacteria.

FIG. 33 shows the results of adding the test compound and irradiating the LED in the above procedure. 33, as in FIG. 31, FA is ferulic acid, VA is vanillic acid, Vani is vanillin, FAOMe is ferulic acid methyl ester, CaA is caffeic acid, GA is gallic acid, CA is coumaric acid, and ChA is chlorogen. DMSO indicates the case where the test compound was not added, Initial indicates the initial bacterial count, and 40 min indicates the bacterial count after LED irradiation for 40 minutes (irradiation energy of 203 J / cm ² ).

  As shown in FIG. 33, when CaA, GA, CA, and ChA were used as test compounds, the number of bacteria was smaller than when no test compound was used (DMSO in the table). Decreased by 72%, 58%, 78% and 81% compared to the number of new bacteria. On the other hand, when FA, VA, Vani, and FAOMe were used as test compounds, a remarkable decrease in the number of bacteria was observed, and all of them decreased by 99% or more compared with the number of initial bacteria. From this, it was confirmed that when FA, VA, Vani, and FAOMe were used as compounds, the growth of fungi could be remarkably suppressed.

  In addition, FIG. 34 shows the result of the above procedure, in which the test compound was similarly added but LED irradiation was not performed. As shown in FIG. 34, when the test compound was similarly added but LED irradiation was not performed, no significant decrease in the number of bacteria was observed after 40 minutes regardless of the type of the test compound. The result was almost the same as the case where no LED was added and no LED irradiation was performed (DMSO in FIG. 34). From this, it was found that the number of bacteria was not reduced only by bringing the test compound into contact with the microorganism. In addition, from the results of FIGS. 33 and 34, the use of the combination of the contact with FA, VA, Vani, and FAOMe together with the LED irradiation resulted in a further remarkable decrease in the number of bacteria, and therefore, the growth of microorganisms was significantly suppressed. Was confirmed.

Claims (13)

Including a step of irradiating the target with visible light using a visible light LED as a light source, a method for suppressing the growth of microorganisms in the target,
Here, the irradiation is performed such that the peak wavelength of the visible light LED is in the range of 405 to 421 nm, the illuminance is 4 mW / cm ² or more, and the irradiation energy is 7.5 J / cm ² or more. Features, methods. Illuminance is 4~500mW / cm ^2, The method of claim 1. The method according to claim 1, wherein the irradiation energy is 7.5 to 500 J / cm ² . The method according to claim 1, wherein the irradiation time is 1 to 60 minutes. The method according to any one of claims 1 to 4, wherein the object is at least one selected from the group consisting of marine products, agricultural products, livestock products, and processed products thereof. The method according to any one of claims 1 to 5, further comprising a step of irradiating the object with ultraviolet light or visible light having a peak wavelength in a range from 265 nm to less than 405 nm. The method according to any one of claims 1 to 6, further comprising a step of contacting the object with a compound represented by the following general formula (1):
(Wherein, R ₁ represents a linear or branched alkyl group having 1 to 4 carbon atoms, and R ₂ represents a hydrogen atom, a halogen atom, or a linear or branched alkoxy group having 1 to 4 carbon atoms. R ₃ represents a direct bond, a linear alkylene group having 1 to 12 carbon atoms, a linear alkenylene group having 2 to 12 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms. Alternatively, it represents a linear alkynylene group having 2 to 12 carbon atoms, and R ₄ represents a hydrogen atom, a hydroxyl group, or a linear alkoxy group having 1 to 18 carbon atoms.
Here, a linear alkylene group having 1 to 12 carbon atoms represented by R ₃ , a linear alkenylene group having 2 to 12 carbon atoms and a linear alkynylene group having 2 to 12 carbon atoms, and a carbon atom represented by R ₄ On the linear alkoxy groups of formulas 1 to 18, each independently represents a halogen atom, a hydroxyl group, an amino group, a sulfo group, a nitro group, a cyano group, a keto group, an isocyanate group, an isothiocyanate group, a carbon number of 1 to 18. At least one group selected from the group consisting of 18 linear or branched alkyl groups, phenyl groups and cyclohexyl groups may be substituted. ) A visible light irradiation device used to suppress the growth of microorganisms in an object,
Equipped with an irradiator that irradiates visible light to the object using a visible light LED as a light source,
The irradiating unit irradiates visible light so that the peak wavelength is in a range of 405 to 421 nm, the illuminance is 4 mW / cm ² or more, and the irradiation energy is 7.5 J / cm ² or more. . Further comprising a support portion for supporting the object,
The visible light irradiation device according to claim 8, wherein the irradiation unit is arranged to irradiate visible light to an object supported by the support unit. The support unit is a conveyor that conveys an object,
The visible light irradiation device according to claim 9, wherein the irradiation unit is arranged to irradiate the object conveyed by the conveyor with visible light. The support unit is a container that stores at least a part of the target object,
The visible light irradiation device according to claim 9, wherein the irradiation unit is arranged to irradiate a visible light to an object stored in the storage body. The visible light irradiation device according to claim 8, wherein the irradiation unit further includes a light source that irradiates an object with ultraviolet light or visible light having a peak wavelength in a range from 265 nm to less than 405 nm. The visible light irradiation device according to any one of claims 8 to 12, further comprising a contact portion for bringing a compound represented by the following general formula (1) into contact with the target object:
(Wherein, R ₁ represents a linear or branched alkyl group having 1 to 4 carbon atoms, and R ₂ represents a hydrogen atom, a halogen atom, or a linear or branched alkoxy group having 1 to 4 carbon atoms. R ₃ represents a direct bond, a linear alkylene group having 1 to 12 carbon atoms, a linear alkenylene group having 2 to 12 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms. Alternatively, it represents a linear alkynylene group having 2 to 12 carbon atoms, and R ₄ represents a hydrogen atom, a hydroxyl group, or a linear alkoxy group having 1 to 18 carbon atoms.
Here, a linear alkylene group having 1 to 12 carbon atoms represented by R ₃ , a linear alkenylene group having 2 to 12 carbon atoms and a linear alkynylene group having 2 to 12 carbon atoms, and a carbon atom represented by R ₄ On the linear alkoxy groups of formulas 1 to 18, each independently represents a halogen atom, a hydroxyl group, an amino group, a sulfo group, a nitro group, a cyano group, a keto group, an isocyanate group, an isothiocyanate group, a carbon number of 1 to 18. At least one group selected from the group consisting of 18 linear or branched alkyl groups, phenyl groups and cyclohexyl groups may be substituted. )