JP6646320B2 - Sterilization treatment method - Google Patents

Description

The present invention relates to a powdery or granular, or dry sterilization how to sterilize an object to be processed of the foliage and the like.

  For example, a sterilization method for performing a heat sterilization process while conveying an object to be processed such as food is known. Generally, in such a sterilization treatment method, high-temperature steam such as saturated steam, high-pressure steam, or superheated steam is used as a heating medium. The treatment method using saturated steam is a method in which steam heated to about 100 to 120 ° C. is filled in a heating chamber into which an object to be processed is carried, and sterilized by heating. The treatment method using high-pressure steam is a heating method using pressurized and heated saturated steam as a heating medium. The treatment method using superheated steam is a method in which high-pressure steam generated from a boiler is further heated, and superheated steam heated to 140 ° C. or higher is injected into a heating chamber to heat an object to be processed.

  Conventionally, as a processing method using superheated steam, a configuration disclosed in Patent Document 1 is known. Patent Literature 1 discloses a method of sterilizing a powder, in which superheated steam is uniformly contacted, the powder is heated to a temperature of 200 to 350 ° C, and then cooled to a predetermined temperature.

JP 2002-360196 A

  However, when a powdered or granular foliage or the like is used as the material to be treated, or when a dried foliage or the like is used, a saturated steam or a high-pressure steam generally used in a sterilization treatment is applied. However, there is a problem that the object absorbs moisture and the quality may change. Further, when superheated steam is applied in the sterilization process, there is a problem that the quality of the object to be processed may change due to a high temperature during the process.

It is an object of the present invention is to provide powdery or granular, or dry sterilized how the quality change of the foliage and the like can be suppressed.

  The present invention has found that by using a dispersion in which fine water droplets are dispersed in superheated steam as a heating medium, sterilization can be performed while suppressing quality deterioration of powdery or granular, or dried foliage and the like. It is based on.

  In order to achieve the above object, according to one aspect of the present invention, in the method for sterilizing at least one kind of the object to be treated selected from powdered or granular foliage, algae, fungi, spice seeds, and spices, A sterilization method comprising contacting an object with a dispersion in which fine water droplets are dispersed in superheated steam as a heating medium is provided.

  In another aspect of the present invention, in the method for disinfection of at least one kind of an object selected from foliage, algae, fungi, spice seeds, and spices having a water content of 20% by mass or less, And a dispersant in which fine water droplets are dispersed in superheated steam as a heating medium.

  In the sterilization treatment, the heating temperature is 103 to 145 ° C, the contact time between the dispersion and the object to be treated is 4 to 150 seconds, and the content of fine water droplets in the dispersion is 5 to 5 seconds. To 55% by mass.

  The object may be at least one selected from tea, leafy vegetables, seaweeds, mushrooms, sesame, and pepper. The object may have an increase in water content after the sterilization treatment of 10% by mass or less with respect to the water content before the sterilization treatment.

  In another aspect of the present invention, in the sterilization processing apparatus used in the sterilization processing method, a transport unit that transports the workpiece, a heating chamber that heats the workpiece transported by the transport unit, A heating means for heating the inside of the chamber, and a heating medium injection nozzle for generating a dispersion in which fine water droplets are dispersed in superheated steam as a heating medium and continuously injecting the dispersion into the heat treatment chamber are connected. A sterilization apparatus is provided, which includes a heating medium generation unit as a component, and performs heat sterilization while transporting the object. The transfer means may include a transfer belt, and the transfer belt may be made of a synthetic resin containing aromatic polyether ketone.

  ADVANTAGE OF THE INVENTION According to this invention, the quality change of powdery or granular foliage can be suppressed.

The side view which shows the schematic structure of the sterilization processing apparatus of this embodiment. Sectional drawing in the horizontal direction which shows the schematic structure of the heat processing chamber containing the heating medium production | generation means of the sterilization processing apparatus of this embodiment.

(First embodiment)
Hereinafter, a first embodiment of a sterilization method embodying the present invention will be described with reference to FIGS.

  A sterilization method including a step of contacting a dispersion of fine water droplets in superheated steam as a heating medium with the object to be treated of the present embodiment is a powdered or granular foliage, algae, fungi, and the like as the object to be treated. At least one selected from condiment seeds and spices (hereinafter referred to as "powder or granular foliage") is applied. These may be used alone or in combination of two or more. Among them, it is preferably applied to powdered or granular foliage and spices.

  Examples of the foliage include tea, leaf stem vegetables and the like. Powdered tea includes powdered tea, powdered tea, and matcha. Known vegetables can be appropriately adopted as the leaf stem vegetables, such as Chinese cabbage, cabbage, spinach, lettuce, broccoli, leek, and onion. Examples of the algae include seaweeds such as laver, kelp, seaweed, and hijiki. Examples of fungi include mushrooms such as shiitake mushroom, mushroom, enokitake mushroom, and shimeji mushroom. Examples of spice seeds include sesame, walnut, and peanuts. The powdered or granular sesame includes both sesame seed itself and sesame seed ground. The spices include, for example, pepper, pepper, seven-star chili pepper or a material thereof. Powdered or granular pepper or pepper includes both those fruits themselves and those obtained by grinding those fruits.

  The size of the object to be processed is, specifically, an average particle diameter measured by a laser diffraction / scattering particle size distribution measuring device, preferably 50 μm to 5 mm, more preferably 100 μm to 3 mm, and still more preferably 200 μm to If it is within the range of about 2 mm, it can be appropriately adopted. The powdery or granular forms include, for example, granulated granules, pulverized forms, and refined forms.

  The moisture content of the object to be treated by the sterilization method is not particularly limited, but the sterilization method of the present embodiment can be applied to, for example, an object having a high drying rate. The water content of the object to be treated is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less. When applied to a raw material having a high drying rate, the content of dietary fiber in the material to be treated is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. When the content of the dietary fiber is 10% by mass or more, moisture absorption is suppressed when the sterilization treatment is performed by the heating medium, and quality retention such as suppression of an increase in the water content can be further improved.

  A method for producing a dispersion in which fine water droplets are dispersed in superheated steam as a heating medium is not particularly limited, and the dispersion can be produced using a known device. As a method of sterilizing by contacting an object to be processed in a heat treatment atmosphere of a dispersion in which fine water droplets are dispersed in superheated steam, for example, a method of using a sterilizing apparatus 10 shown in FIG. it can. Hereinafter, the sterilization apparatus 10 used in the sterilization method of the present embodiment will be described.

  As shown in FIG. 1, a transport belt 11 that constitutes a transport unit of the sterilization apparatus 10 is an endless belt made of a synthetic resin, and includes a drive roll 12 disposed upstream and downstream in a transport direction. 13 is wound. The transport belt 11 is formed in a cloth shape having air permeability, and has a transport surface 11a on an upper surface. The material of the conveyor belt is not particularly limited as long as it is a synthetic resin having heat resistance, but engineering plastic is preferably used. Examples of the engineering plastic include polyamide such as nylon, aromatic polyether ketone such as polyether ether ketone, polyphenylene sulfide, polycarbonate, and polyester. These may be used alone or in combination of two or more. Among these, aromatic polyetherketones such as polyetheretherketone, which are excellent in heat resistance and durability, and excellent in washing property and drying property at the time of regeneration of the conveyor belt 11, are preferable. Examples of the cloth include a knitted fabric, a woven fabric, and a nonwoven fabric. Among these, a knitted or woven fabric which is easy to secure air permeability by forming a mesh is preferable.

  Above the upstream side in the transport direction of the transport belt 11, a hopper 14 is fixed to the main body of the sterilization apparatus 10 (not shown), and the lower end of the hopper 14 adjusts the discharge amount of the workpiece on the transport surface 11a. A discharge port 15 that discharges while discharging is provided. On the downstream side in the transport direction of the hopper 14, the thickness of the workpiece loaded on the transport belt 11 (the height from the upper surface of the transport belt 11 to the upper surface of the workpiece loaded on the transport belt 11) is set. A thickness adjustment plate 16 for adjustment is attached to the main body of the sterilization apparatus 10 so as to be movable in the vertical direction.

  On the downstream side of the adjusting plate 16 in the transport direction, a heat treatment device 17 is fixed to the main body of the sterilization treatment device 10. The heat treatment apparatus 17 is provided therein with a heat treatment chamber 17a for performing heat treatment with a dispersion in which fine water droplets are dispersed in superheated steam. An inlet 17 b for carrying in the conveyor belt 11 is formed in the side surface on the upstream side in the conveyance direction of the heat treatment device 17. An outlet 17c for carrying out the conveyor belt 11 is formed on the side surface of the heat treatment device 17 on the downstream side in the conveyance direction. The heat treatment device 17 has the transport belt 11 inserted from the inlet 17b to the outlet 17c.

  Above the heat treatment chamber 17a, a heating chamber 17e is provided via a partition plate 18. The upstream end of the partition plate 18 in the transport direction is provided to be separated from the upstream wall surface in the transport direction in the heat treatment chamber 17a, and a communication path 20 that communicates with the heat treatment chamber 17a through the separated gap is provided. Is formed. The lower end of the partition plate 18 in the transport direction is provided separately from a wall surface on the downstream side in the transport direction in the heat treatment chamber 17a, and a communication path 21 that communicates with the heat treatment chamber 17a through the separated gap is provided. Is formed. At the center of the partition plate 18 in the left-right direction and the front-back direction, a circular intake port 18a for taking in the heating medium in the heat treatment chamber 17a is opened.

  The heating chamber 17 e is formed between the upper surface 18 b of the partition plate 18 and the inner surface 17 f of the top plate 17 d of the heat treatment device 17. The heating chamber 17e is provided with a suction fan 22 for sucking the heating medium in the heat treatment chamber 17a from the intake port 18a, and coiled heating units 23 and 24 as heating means. The suction fan 22 is formed of a plurality of blades, and is rotatably attached to the top plate 17d above the intake port 18a. The suction fan 22 is connected to a motor (not shown), and rotates so as to suck the heating medium in the heating chamber 17a from the inlet 18a and send the heating medium into the heating chamber 17e. The coil-shaped heating units 23 and 24 are arranged such that the axis of the coil is parallel to the conveying method on each of the upstream side and the downstream side of the suction fan 22 in the conveying direction. The coil-shaped heating units 23 and 24 are suspended from the inner surface 17f of the top plate 17d by the respective wires 23a and 24a at both ends. Heating medium injection nozzles 25 to 27 are fixed to the inner wall of the heat treatment chamber 17a.

  As illustrated in FIG. 2, the heating medium injection nozzle 25 is formed in a tubular shape, and when viewed from the front side of the sterilization apparatus 10 (when viewed from the downstream side in the transport direction to the upstream side), The longitudinal direction is arranged to be perpendicular to the transport direction. On the side surface of the heating medium injection nozzle 25, a plurality of ejection ports 25a for ejecting a dispersion in which fine water droplets are dispersed in superheated steam are formed. As shown in FIG. 1, one heating medium injection nozzle 25 is provided below the transport belt 11 on the upstream side and the downstream side in the transport direction of the heat treatment chamber 17a. The two heating medium ejection nozzles 25 are arranged such that the ejection ports 25a face the upstream and downstream directions in the transport direction, respectively, and that the ejection ports 25a of the heating medium ejection nozzles 25 face each other. The two heating medium injection nozzles 25 are connected to two heating medium generating units 33, respectively. The heating medium generating means 33 includes a heating chamber 29 fixed to the main body of the sterilization apparatus 10 outside the heating apparatus 17 and a heating pipe 28 connecting the heating chamber 29 and the heating medium injection nozzle 25. , And a supply pipe 30 for supplying water into the heating chamber 29.

  The heating medium injection nozzle 26 is formed in a tubular shape, similarly to the heating medium injection nozzle 25, such that the left and right longitudinal directions are perpendicular to the transport direction when viewed from the front side of the sterilization apparatus 10. Are arranged. Similarly to the heating medium injection nozzle 25, a plurality of ejection ports 26a for ejecting a dispersion in which fine water droplets are dispersed in superheated steam are formed on the side surface of the heating medium injection nozzle 26. As shown in FIG. 1, one heating medium injection nozzle 26 is provided above the transport belt 11 on the upstream side and the downstream side in the transport direction of the heat treatment chamber 17a. The two heating medium ejection nozzles 26 are arranged such that the ejection ports 26a face the upstream and downstream sides in the transport direction, respectively, and that the ejection ports 26a of the heating medium ejection nozzles 26 face each other. The two heating medium injection nozzles 26 are connected to the two heating medium generation units 33 via the heating pipes 31 similarly to the heating medium injection nozzle 25.

  The heating medium injection nozzle 27 is provided in a pair at the upper part of the heat treatment chamber 17a at a position sandwiching the intake port 18a from the left-right direction of the sterilization apparatus 10. On the lower surface of the heating medium jet nozzle 27, a jet port 27a for jetting a dispersion in which fine water droplets are dispersed in superheated steam is arranged so as to face the vertically lower transport surface 11a. The two heating medium injection nozzles 27 are connected to the two heating medium generation units 33 via the heating pipes 32, respectively, similarly to the heating medium injection nozzle 25.

  The transport belt 11 moves toward the drive roll 13 on the downstream side in the transport direction of the heat treatment device 17, is folded downward by the drive roll 13, and the transport surface 11 a is directed downward. A collecting means 34 for collecting the processed material after the heat treatment is provided below the driving roll 13. The collection means 34 has an opening 34a at the upper end for receiving the processed material when the processed material falls by gravity from the transport surface 11a of the transport belt 11 that transports the peripheral surface of the drive roll 13. On the transport surface 11a of the transport belt 11, which is located above the collecting means 34 and is turned downward from the drive roll 13, a peeling device 35 for separating adhered matter fixed to the main body of the sterilization apparatus 10 is provided. ing. The shape of the peeling device 35 can be set as appropriate depending on the type and size of the processed object. For example, a spatula shape, a blade shape, a brush shape, or the like can be employed.

  A spraying means 38 is provided downstream of the peeling device 35 in the return direction via tension pulleys 36 and 37. The spraying means 38 is fixed to the main body of the sterilization apparatus 10 at a lower portion of the sterilization apparatus 10 via a steam supply pipe (not shown). The spraying means 38 includes a steam supply pipe and two tubular steam injection nozzles 38 a connected to the steam supply pipe and extending in the width direction of the conveyor belt 11. The two steam injection nozzles 38a are arranged in parallel, and are arranged so as to be horizontal with the back surface 11b of the conveyor belt 11. An outlet 38b for injecting steam is formed below the steam injection nozzle 38a. A plurality of ejection ports 38b are formed at equal intervals in the longitudinal direction of the steam ejection nozzle 38a in order to eject steam over the entire width of the conveyor belt 11. The ejection port 38b is vertically directed downward so as to face the rear surface 11b of the transport belt 11 that is directed upward.

  Downstream of the spraying means 38 in the return direction, cylindrical drum dryers 40 and 41 are rotatably attached to the main body of the sterilization apparatus 10 via a tension pulley 39. The drum dryers 40 and 41 are configured such that a heating medium, for example, steam is charged into the inside of a rotating cylindrical drum, and the drum surface can be heated. The drum dryer 40 is arranged on the upstream side in the return direction, and is configured such that the transport peripheral surface is in contact with the back surface 11b of the transport belt 11 while rotating in the return direction. The drum dryer 41 is arranged on the downstream side in the return direction, and is configured such that the transport peripheral surface contacts the transport surface 11a of the transport belt 11 while rotating in the return direction. The transport belt 11 that has passed through the drum dryer 41 returns to the drive roll 12.

A method of performing the sterilization processing method of the present embodiment using the sterilization processing apparatus 10 will be described.
First, an object to be processed is continuously applied from the discharge port 15 of the hopper 14 to the transport surface 11a of the transport belt 11 that is movable in the transport direction, and a process of placing the object on the transport surface 11a is performed. The thickness of the object to be processed, which has been dispensed onto the transport surface 11a, is adjusted by the height of the adjusting plate 16 while being transported. The thickness of the workpiece on the transport surface 11a is not particularly limited, and is appropriately set within a practical range from the viewpoint of the type or size of the workpiece. Specifically, it is preferably set within a range of 4 to 22 mm, more preferably 6 to 20 mm, from the viewpoints of certainty, efficiency, and quality retention of the sterilization treatment. Next, the processed object whose thickness has been adjusted is carried into the heat treatment chamber 17a from the entrance 17b of the heat treatment device 17, and subjected to a heat sterilization process.

  After the object to be processed is carried into the heat treatment chamber 17a, a dispersion F in which fine water droplets are dispersed in superheated steam as a heating medium is ejected from each of the ejection ports 25a to 27a of the heating medium ejection nozzles 25 to 27. You. The dispersion F is supplied from the heating medium generator 33. First, a predetermined amount of water is supplied from the supply pipe 30 into the heating chamber 29 via a pump (not shown) connected to the supply pipe 30. The supply amount of water is appropriately set depending on the temperature in the heat treatment chamber 17a, the content of fine water droplets in the dispersion, and the like. By boiling the inside of the heating chamber 29 at a predetermined temperature and a predetermined pressure, a gas-liquid mixture composed of steam M and hot water H is generated in the heating pipes 28, 31, 32. The steam M and the hot water H in the heating pipes 28, 31, 32 are changed by the pressure of the water from the supply pipe 30 and the pressure of the steam generated by the boiling, to the respective ejection ports 25 a to 27 a of the heating medium injection nozzles 25 to 27. Thus, the dispersion F in which the superheated steam and the fine water droplets are mixed is ejected into the heat treatment chamber 17a. The temperature and pressure in the heating chamber 29 are appropriately set according to the temperature in the heat treatment chamber 17a, the content of fine water droplets in the dispersion, and the like. For example, conditions of 120 ° C. or higher and 0.19 MPa or higher are adopted. Accordingly, the dispersion F in which superheated steam controlled to about 115 ° C. and high-temperature fine water droplets are mixed can be ejected into the heat treatment chamber 17a.

  The heating temperature in the heat treatment chamber 17a is appropriately set within a practical range from the viewpoint of the type or size of the object to be treated. The lower limit of the temperature in the heat treatment chamber 17a is preferably 103 ° C or more, more preferably 105 ° C or more, from the viewpoint of improving the reliability or efficiency of the sterilization treatment. The upper limit of the temperature in the heat treatment chamber 17a is preferably 145 ° C or lower, more preferably 140 ° C or lower, from the viewpoint of maintaining quality.

  The content of fine water droplets in the dispersion F (superheated steam + fine water droplets) jetted into the heat treatment chamber 17a is appropriately set within a practical range from the viewpoint of the type or size of the object to be processed. You. The lower limit of the content of the fine water droplets in the dispersion F is preferably 5% by mass or more, more preferably 10% by mass or more, from the viewpoint of improving the reliability or efficiency of the sterilization treatment. The upper limit of the content of the fine water droplets in the dispersion F is preferably 55% by mass or less, more preferably 51% by mass or less, and further preferably 49% by mass or less, from the viewpoint of maintaining quality.

  The dispersion F ejected into the heat treatment chamber 17a is sent by the suction fan 22 from the inlet 18a to the heating chamber 17e provided above the heat treatment chamber 17a. The dispersion F sent to the heating chamber 17e is sent to the coiled heating units 23 and 24, respectively, and reheated. Part of the reheated dispersion F returns to the inside of the heat treatment chamber 17a through the communication passages 20 and 21 which communicate with the heat treatment chamber 17a as partially heated superheated steam. Thereby, the heat treatment atmosphere in the non-closed heat treatment chamber 17a having the inlet 17b and the outlet 17c is maintained.

  In the step of performing the heat sterilization process, the object to be processed may be processed while the conveyor belt 11 is operating, or may be processed while the conveyor belt 11 is stopped. Further, the heating medium may be injected from all of the heating medium injection nozzles 25 to 27, and a part of the heating medium is designed to be stopped in consideration of the temperature in the heating processing chamber 17a, the type or amount of the object to be processed, and the like. Is also good. The contact time between the dispersion F and the object to be processed, that is, the transport time of the object to be processed in the heat treatment chamber 17a is appropriately determined from the viewpoint of the type or size of the object to be processed and the temperature in the heat treatment chamber 17a. It is set within the above range. The lower limit of the contact time between the dispersion F and the object to be treated is preferably 4 seconds or more, more preferably 8 seconds or more, and still more preferably 12 seconds or more, from the viewpoint of improving the reliability or efficiency of the sterilization treatment. The upper limit of the contact time between the dispersion F and the object to be treated is preferably 150 seconds or less, more preferably 100 seconds or less, and still more preferably 50 seconds or less, from the viewpoint of maintaining quality.

  The processed material after the heat treatment is carried out from the outlet 17c of the heat treatment apparatus 17, sent to the collecting means 34 on the downstream side in the transport direction, and the collecting step is performed. The heat-treated material drops by gravity from the transport surface 11 a of the transport belt 11 that transports the peripheral surface of the drive roll 13, and is recovered from the opening 34 a of the recovery unit 34. The processing object adhering to the transport surface 11a is scraped off by the peeling device 35.

  The water content of the collected processed material is not particularly limited, but when a dried object is applied, the water content after the sterilization treatment is preferably 20% by mass or less, more preferably 15% by mass or less. is there. In addition, the increase in the water content of the treated material after the sterilization treatment relative to the moisture content of the treated material before the sterilization treatment is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 4% by mass. It is as follows. In the case where the value is within such a numerical range, the dried processed product can be sterilized while suppressing an increase in the water content. Further, it is not necessary to newly provide a step of performing a drying treatment in order to reduce the increased water content.

  After the processed material is collected, the conveyor belt 11 is sent to the spraying means 38 via the tension pulleys 36 and 37 on the downstream side in the return direction of the peeling device 35, and a cleaning process is performed. The transport belt 11 turned downward by the drive roll 13 has the transport surface 11a directed downward, and is supplied from the steam supply pipe to the rear surface 11b directed upward from the outlet 38b of the spraying means 38. Water vapor is injected. As a result, from the rear surface 11b side of the transport surface 11a, the processed material and the like attached to the transport surface 11a are washed and removed.

  The transport belt 11 that has been subjected to the cleaning process is sent to cylindrical drum dryers 40 and 41 via a tension pulley 39, and a drying process is performed. When the back surface 11b of the conveyor belt 11 comes into contact with the peripheral surface of the heated drum dryer 40, the back surface 11b side is mainly dried. Next, the transport surface 11a of the transport belt 11 is brought into contact with the peripheral surface of the heated drum dryer 41, so that the transport surface 11a side is mainly dried. The transport belt 11 that has passed through the drum dryer 41 returns to the drive roll 12 and is folded upward, so that the transport surface 11a is directed upward. The object to be processed is loaded on the transport belt 11 again, and a continuous sterilization process is performed on the object to be processed.

Next, the operation of the sterilization method of the above embodiment will be described.
For example, a sterilization apparatus 10 is used as a method for sterilizing an object to be processed such as a powdery or granular foliage. The transport belt 11 of the sterilization apparatus 10 transports the workpiece into the heat treatment chamber 17a with the workpieces loaded on the transport surface 11a. In the heat treatment chamber 17a, a dispersion F in which fine water droplets are dispersed in superheated steam as a heating medium is ejected from each of the ejection ports 25a to 27a of the heating medium ejection nozzles 25 to 27 into the heat treatment chamber 17a. After the dispersion F is sent to the coil-shaped heating portions 23 and 24 of the heating chamber 17e and reheated, a part of the dispersion F returns to the heat treatment chamber 17a as superheated steam whose volume has expanded. In such a heat treatment atmosphere in the heat treatment chamber 17a, condensation heat transfer is generated on the surface of the object to be treated by high-temperature fine water droplets. Then, due to the superheated steam, the fine water droplets which have lost the latent heat due to the condensation heat transfer evaporate into the superheated steam. Thereby, a heating characteristic in which the influence of the condensed water on the object to be treated is small and the decrease in the internal moisture due to the evaporation is small is obtained. In particular, a dried powdery or granular object having a low water content can be sterilized without increasing the water content while maintaining a dry state. In addition, an object to be processed that is vulnerable to prolonged high-temperature heating can be sterilized while suppressing deterioration in quality such as appearance, aroma, flavor, and components.

According to the sterilization method of the present embodiment, the following effects can be obtained.
(1) In the present embodiment, a dispersion F in which fine water droplets are dispersed in superheated steam is applied as a heating medium in a method for sterilizing an object to be treated such as a powdery or granular foliage. Therefore, the temperature is not too high as compared with the heat treatment using only superheated steam, so that the deterioration of the quality of the powdery or granular foliage can be suppressed.

  Saturated steam or high-pressure steam, which is generally used in sterilization treatment, absorbs moisture in the object to be treated, and the quality may change.However, by applying the dispersion F, powdery or granular Deterioration of quality of foliage and the like can be further suppressed.

  Further, when superheated steam is applied in the sterilization process, there is a problem that the quality of the object to be processed may change due to a high temperature during the process. In addition, the superheated steam has a problem that it is difficult to obtain a wet heat sterilization effect and the sterilization effect is weakened by drying the object during sterilization. By applying the dispersion F, the sterilization effect can be improved while suppressing the deterioration of the quality of the powdery or granular foliage and the like.

  (2) Preferably, as conditions for the sterilization treatment, the temperature in the heat treatment chamber 17a is 103 to 145 ° C, the contact time between the dispersion F and the object to be treated is 4 to 150 seconds, The content of the fine water droplets in the body F is 5 to 55% by mass. Therefore, by applying these numerical ranges, it is possible to more surely sterilize the object to be treated such as powdered or granular foliage while maintaining the quality.

  (3) The sterilization apparatus 10 includes a heat treatment chamber 17a for heating an object to be processed conveyed by the conveyance belt 11, a coiled heating unit 23 for heating the inside of the heat treatment chamber 17a, and the like, and a dispersion medium F as a heating medium. And a heating medium generating means 33 connected to a heating medium injection nozzle 25 for continuously injecting into the heat treatment chamber 17a. Therefore, the sterilization method of the present embodiment can be easily and more reliably performed.

  In addition, the dispersion F is continuously injected into the heat treatment chamber from the heating medium injection nozzle 25 and the like, and the heat treatment is performed while the object is conveyed. And a more efficient sterilization treatment can be performed.

  (4) As the transport belt 11 of the present embodiment, preferably, an aromatic polyetherketone such as polyetheretherketone is used. Therefore, since it is excellent in heat resistance and durability, it is preferably used in a sterilization treatment apparatus 10 having a sterilization treatment step using a dispersion F in which fine water droplets are dispersed in superheated steam as a heating medium and a washing step using steam. can do.

  In addition, the object to be treated, such as a powdery or granular foliage, is unlikely to adhere to the conveyor belt 11 and is excellent in cleanability at the time of cleaning, so that the sanitary state of the belt can be maintained. Further, since the drying process is excellent in drying property, the drying process can be performed in a short time, and the process can be preferably applied to the continuous sterilization process of a drying process target material.

(Second embodiment)
Hereinafter, a second embodiment of a sterilization method embodying the present invention will be described. Hereinafter, the description will focus on the differences from the first embodiment.

  The sterilization method including the step of contacting the object to be treated of the present embodiment with a dispersion in which fine water droplets are dispersed in superheated steam as a heating medium includes a predetermined dried foliage, algae, fungi, and spices as the object to be treated. It is applied to at least one selected from seeds and spices (hereinafter referred to as “dried foliage, etc.”). These may be used alone or in combination of two or more. Among them, it is preferably applied to a dried algae.

  With respect to the dried foliage and the like as the object to be treated in the sterilization treatment method of the present embodiment, specifically, the moisture content of the object to be treated is 20% by mass or less, preferably 15% by mass or less. The sterilization method of the present embodiment can be applied to an object to be processed having a high drying rate. Further, the content of dietary fiber in the material to be treated is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. When the content of the dietary fiber is 10% by mass or more, moisture absorption is suppressed when the sterilization treatment is performed by the heating medium, and quality retention such as suppression of an increase in the water content can be further improved.

  The size of the object to be treated is not particularly limited, and for example, may be appropriately selected from a roughly pulverized or cut shape to a finely pulverized shape. For example, if the average particle size measured by a laser diffraction / scattering type particle size distribution measuring device is within a range of preferably about 50 μm to 5 cm, more preferably about 100 μm to 3 cm, and still more preferably about 200 μm to 1 cm. It can be adopted as appropriate. The powdery or granular forms include, for example, granulated granules, pulverized forms, and refined forms.

  As a method of sterilizing by contacting a dispersion obtained by dispersing fine water droplets in superheated steam with a dried foliage body or the like as an object to be treated, for example, using a sterilizing apparatus 10 shown in FIG. It can be implemented by a method similar to that of the first embodiment.

According to the sterilization treatment method of the present embodiment, the following effects can be obtained in addition to the effects of the first embodiment.
(5) In the present embodiment, in the method for sterilizing an object to be treated such as a dried foliage having a water content of 20% by mass or less, a dispersion F in which fine water droplets are dispersed in superheated steam as a heating medium is used. Applied. Therefore, even when these objects are treated with a heating medium, an excellent sterilizing effect can be exhibited while suppressing quality deterioration. In other words, a dried object having a low moisture content can be sterilized without increasing the moisture content while maintaining a dry state.

  (6) Preferably, the present invention is applied to a dried foliage or the like having a dietary fiber content of 10 mass% or more in the processed material. Such an object can be sterilized while maintaining the quality.

The above embodiment may be modified as follows.
-The application field of the to-be-processed object to which the sterilization method of the said embodiment is applied is not specifically limited. For example, foods, pharmaceuticals, cosmetics, chemicals, or raw materials thereof may be mentioned.

  The sterilization apparatus in which the sterilization method of the above-described embodiment is performed is not limited to the sterilization apparatus 10 having the conveyor belt 11 and capable of performing continuous sterilization, and disperses fine water droplets in superheated steam. Any heating device that can generate a dispersed material can be appropriately used. For example, an apparatus of a batch type, a stirring heating type, or the like can be used.

  The means for feeding the object to be processed onto the transport surface 11a is not particularly limited, and a known feeding means other than the hopper 14 such as a screw feeder, an air feeder, and a vibration feeder can be appropriately used. They can be adjusted in the amount of unloading by means of each power source. Further, it may be one end of the conveying means of another process different from the sterilization treatment device 10.

The air permeability of the conveyor belt 11 can be appropriately set from the viewpoint of the thickness and durability of the belt, and is preferably 10 cm ³ / cm ² · sec or more, more preferably 100 cm ³ / cm ² · sec or more. . The air permeability of the belt can be determined from the amount of air passing (cm ³ / cm ² · sec) using a Frazier-type air permeability tester based on JIS L1096 “General Fabric Testing Method”.

  The transport belt 11 may have a configuration other than a predetermined cloth shape as long as the configuration has air permeability. For example, a film or a sheet provided with a plurality of holes having a predetermined inner diameter may be used.

  In the sterilization apparatus 10, the number of drive rollers or tension pulleys is not particularly limited. However, in the heat treatment chamber 17a, it is preferable not to dispose various rollers on the lower surface of the transport belt 11 so as not to prevent diffusion of the dispersion F, transmission of the dispersion F through the transport belt 11, and the like.

  -The width in the left-right direction as viewed from the front of the sterilization apparatus 10 of the above embodiment is not particularly limited, and can be appropriately determined depending on the type and size of the processed material.

Hereinafter, the embodiments will be described more specifically with reference to test examples, but the present invention is not limited thereto.
<Test Example 1: Examination of heating medium>
The sterilization treatment apparatus 10 shown in FIG. 1 was used as a test apparatus, and various heating media were tested for quality retention and sterilization. Powdered tea having an average particle diameter of 1136 μm (water content: 2.5% by mass) measured by a laser diffraction / scattering type particle size distribution measuring device was used as the object to be treated. In each of the examples, the processing is performed with a thickness of the processing object of 11 mm (height from the upper surface of the conveying belt 11 to the upper surface of the processing object stacked on the conveying belt 11; the same applies hereinafter) and a processing time of 15 seconds. Conditions.

  Example 1 used a dispersion in which fine water droplets were dispersed in superheated steam as a heating medium. The conditions were as follows: the temperature in the heat treatment chamber 17a was 115 ° C., the flow rate was 577 mL / min, and the content of fine water droplets in the dispersion was 36.8% by mass.

In Comparative Example 1, only hot air having a temperature of 115 ° C. was circulated in the heat treatment chamber 17a.
Comparative Example 2 was treated in the same manner as Comparative Example 1, except that the temperature was set to 99 ° C.
In Comparative Example 3, only 99 ° C. saturated steam was circulated in the heat treatment chamber 17a.

In Comparative Example 4, only 180 ° C. superheated steam was circulated in the heat treatment chamber 17a.
The resulting processed products of each example were evaluated for quality retention and bactericidal properties according to criteria as described below.

(Quality retention)
The evaluator evaluated the treated product subjected to the sterilization treatment in accordance with the following evaluation criteria from the viewpoint of a change in appearance, aroma, flavor, or quality of components (such as water content) as compared with the untreated product. Regarding the treated product, it is excellent when there is almost no change in quality compared to the untreated product, “○”, and when the quality change is confirmed as compared with the untreated product, but within the range of practicality, “△”, The case where the quality change was large and was not practical as compared with the untreated product was evaluated as "x". Table 1 shows the results.

(Bactericidal)
First, 10 mL of the E. coli group suspension cultured in the Nutrient Broth medium was added to 1 kg of the treated substance in each example before the heat treatment (when the amount of the treated substance was small, the ratio of the suspension to the treated substance was changed. Then, after spraying so as to be uniform, the number of coliform bacteria in the treated product after the heat treatment was measured. To 10 g of the treated product, 90 g of phosphate buffered saline was added, and the number of bacteria in the stomacher-treated solution was measured. In addition, the untreated product sprayed with the coliform bacteria was used as a control to calculate the sterilized ratio.

  Excellent when the sterilized ratio of the applied Escherichia coli is 99.9% or more, "◎", when 99% or more and less than 99.9% is good, "O", when 90% or more and less than 99%. Positive "△", less than 90% was evaluated as "x". Table 1 shows the results.

As shown in Table 1, it was confirmed that Comparative Examples 1 and 2 using hot air could not be sufficiently sterilized. In Comparative Example 3 using the saturated steam, it was confirmed that the water content tended to increase and the quality of the processed product could not be maintained. In Comparative Example 4 using superheated steam, it was confirmed that the heating temperature was high and the quality such as aroma and flavor was reduced. In addition, it was confirmed that the superheated steam does not have a sufficient wet heat sterilization effect, and thus has a tendency to slightly decrease the sterility. On the other hand, it was confirmed that Example 1 using a dispersion in which fine water droplets were dispersed in superheated steam as a heating medium was excellent in sterilization while maintaining quality.

<Test Example 2: Examination of object to be treated>
In a sterilization treatment method using a dispersion in which fine water droplets were dispersed in superheated steam as a heating medium, tests were performed on various objects to be treated. In each example, the sterilization treatment apparatus 10 shown in FIG. 1 was used as a test apparatus, the temperature in the heat treatment chamber 17a was 115 ° C., the treatment time was 15 seconds, the flow rate was 577 mL / min, the thickness of the object to be treated was 11 mm, and the dispersion was The condition of the content of fine water droplets in the body of 36.8% by mass was adopted.

  Example 2 used pepper (water content: 9.8% by mass) having an average particle size of 1146 μm as measured by a laser diffraction / scattering type particle size distribution measuring device. In Example 3, a commercially available bud hijiki (water content: 12.91% by mass) was used. In Example 4, a commercially available cut seaweed (water content: 9.25% by mass) was used.

  In Comparative Example 5, flour (water content: 12.8% by mass) having an average particle size of 45.8 μm measured by a laser diffraction / scattering type particle size distribution measuring device was used. In Comparative Example 6, agar powder having an average particle size of 134 μm (water content: 19.7% by mass) measured by a laser diffraction / scattering type particle size distribution measuring device was used. Comparative Example 7 used sugar (water content: 0.4% by mass) having an average particle size of 644 μm measured by a laser diffraction / scattering type particle size distribution measuring device.

  The treated objects of each example were tested for quality retention and sterilization in the same manner as in Test Example 1. The results are shown in Table 2 together with Example 1 of Test Example 1.

As shown in Table 2, it was confirmed that the quality of each comparative example in which flour, agar, or sugar was applied as a material to be treated was deteriorated even with a powdery food material. It has been confirmed that it is difficult to sterilize flour or the like using a dispersion in which fine water droplets are dispersed in superheated steam as a heating medium.

<Test Example 3: Examination of sterilization treatment conditions>
(1) Processing time The sterilization apparatus 10 shown in FIG. 1 was used as a test apparatus, and the quality retention and sterilization were tested for each processing time shown in Table 3 below. A dispersion in which fine water droplets were dispersed in superheated steam was used as a heating medium. Powdered tea having an average particle diameter of 1136 μm (water content: 2.5% by mass) measured by a laser diffraction / scattering type particle size distribution measuring device was used as the object to be treated.

  In each treatment time, the conditions were as follows: the temperature in the heat treatment chamber 17a was 115 ° C., the flow rate was 577 mL / min, the content of fine water droplets in the dispersion was 36.8% by mass, and the thickness of the object to be treated was 11 mm. . The treated products obtained by the respective treatment times were tested for quality retention and sterilization in the same manner as in Test Example 1. Table 3 shows the results.

As shown in Table 3, it was confirmed that the sterilization properties tended to decrease as the treatment temperature became shorter. On the other hand, it was confirmed that the quality tends to decrease as the processing temperature increases.

(2) Processing Temperature The sterilization apparatus 10 shown in FIG. 1 was used as a test apparatus, and the quality in each of the heat treatment chambers 17a shown in Table 4 below was tested for quality retention and sterilization. A dispersion in which fine water droplets were dispersed in superheated steam was used as a heating medium. Powdered tea having an average particle diameter of 1136 μm (water content: 2.5% by mass) measured by a laser diffraction / scattering type particle size distribution measuring device was used as the object to be treated.

  At each processing temperature, the processing time was 15 seconds, the flow rate of the dispersion was 577 mL / min, and the thickness of the object was 11 mm. The treated products obtained at each treatment temperature were tested for quality retention and sterilization, as in Test Example 1. Table 4 shows the results.

As shown in Table 4, it was confirmed that the higher the processing temperature, the lower the quality. In addition, it was confirmed that the bactericidal properties tended to decrease due to the decrease in fine water droplets as the temperature increased.

(3) Content of Fine Water Drops in Dispersion Using the sterilization treatment device 10 shown in FIG. 1 as a test device, the content of each fine water droplet in the dispersion shown in Table 5 below shows the quality retention and Tested for bactericidal properties. A dispersion in which fine water droplets were dispersed in superheated steam was used as a heating medium. Powdered tea having an average particle diameter of 1136 μm (water content: 2.5% by mass) measured by a laser diffraction / scattering type particle size distribution measuring device was used as the object to be treated.

  Regarding the content of each fine water droplet in the dispersion, the conditions of 115 ° C. in the heat treatment chamber 17a, 15 seconds in the treatment time, and 11 mm in thickness of the object to be treated were adopted. The treated product obtained based on the content of each fine water droplet was tested for quality retention and sterilization in the same manner as in Test Example 1. Table 5 shows the results.

As shown in Table 5, it was confirmed that the higher the content of fine water droplets, the lower the quality.

(4) Thickness of Workpiece on Conveyor Belt 11 The sterilization processing apparatus 10 shown in FIG. 1 was used as a test apparatus. Tested. A dispersion in which fine water droplets were dispersed in superheated steam was used as a heating medium. Powdered tea having an average particle diameter of 1136 μm (water content: 2.5% by mass) measured by a laser diffraction / scattering type particle size distribution measuring device was used as the object to be treated.

  Regarding the thickness of each object to be treated, the temperature in the heat treatment chamber 17a was 115 ° C., the treatment time was 15 seconds, the content of fine water droplets in the dispersion was 36.8% by mass, and the flow rate of the dispersion was 577 mL / min. The conditions were adopted. In the same manner as in Test Example 1, quality-retaining properties and sterilization properties were tested on the processed products obtained according to the thickness of each processed product. Table 6 shows the results.

As shown in Table 6, it was confirmed that when the thickness of the workpiece loaded on the conveyor belt 11 was reduced, the water content tended to increase, and the quality retention was likely to decrease. On the other hand, it was confirmed that the sterilization property tends to decrease when the thickness of the processing object stacked on the transport belt 11 increases.

Next, technical ideas that can be grasped from the above embodiment and other examples will be additionally described below together with their effects.
(A) The sterilization apparatus, wherein the air permeability of the conveyor belt is 10 cm ³ / cm ² · sec or more. Therefore, according to the invention described in (a), the dispersion F can be effectively brought into contact with the object to be processed on the transport belt.

  DESCRIPTION OF SYMBOLS 10 ... Sterilization processing apparatus, 11 ... Conveying belt, 11a ... Conveying surface, 17 ... Heat processing apparatus, 17a ... Heat processing chamber, 17e ... Heating chamber, 22, 23 ... Coiled heating part, 25-27 ... Heating medium injection nozzle , 33: heating medium generating means, F: dispersion, M: steam, H: hot water.

Claims (5)

A method for sterilizing at least one object to be treated selected from foliage, algae, fungi, spice seeds, and spices having a water content of 15 % by mass or less,
A sterilization method comprising: bringing the object to be treated into contact with a dispersion in which fine water droplets are dispersed in superheated steam as a heating medium. The sterilization method according to claim 1 , wherein the object to be processed is in a powder form or a granular form . In the sterilization treatment, the heating temperature is 103 to 145 ° C,
The contact time between the dispersion and the object to be treated is 4 to 150 seconds,
3. The method according to claim 1, wherein the content of the fine water droplets in the dispersion is 5 to 55% by mass. 4.   The sterilization method according to any one of claims 1 to 3, wherein the object to be treated is at least one selected from tea, leaf stem vegetables, seaweeds, mushrooms, sesame, and pepper. Processing method.   The said to-be-processed object is 10 mass% or less of the increase of the water content after a sterilization process with respect to the water content before a sterilization process, The Claims 1 to 4 characterized by the above-mentioned. Sterilization treatment method.