JP7011791B2 - Germination induction method and sterilization method - Google Patents
Germination induction method and sterilization method Download PDFInfo
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- JP7011791B2 JP7011791B2 JP2018019022A JP2018019022A JP7011791B2 JP 7011791 B2 JP7011791 B2 JP 7011791B2 JP 2018019022 A JP2018019022 A JP 2018019022A JP 2018019022 A JP2018019022 A JP 2018019022A JP 7011791 B2 JP7011791 B2 JP 7011791B2
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
- A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
- A23L3/34—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
- A23L3/3409—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
- A23L3/3445—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere comprising other gases in addition to CO2, N2, O2 or H2O
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
- A23L5/00—Preparation or treatment of foods or foodstuffs, in general; Food or foodstuffs obtained thereby; Materials therefor
- A23L5/30—Physical treatment, e.g. electrical or magnetic means, wave energy or irradiation
Description
本発明は、特に、食品等に含まれる芽胞を有する芽胞形成菌の発芽誘導方法および、当該発芽誘導方法を用いた殺菌方法に関するものである。 The present invention particularly relates to a method for inducing germination of spore-forming bacteria having spores contained in foods and the like, and a sterilization method using the method for inducing germination.
従来から、食品や器具等の物体が有する細菌、飲料中に含まれる細菌を不活化する方法が知られている。
例えば、オゾンを用いた粉体の殺菌処理方法が知られている。この殺菌方法によれば、非加熱状態で殺菌できるために、殺菌対象物の劣化を抑制することができる。
しかしながら、このような殺菌方法においては、殺菌の再現性が取れないことがある。即ち、殺菌対象物を同程度オゾンに暴露したとしても、殺菌の程度が処理ごとに異なってしまうという事態が発生する。
この殺菌の再現性が取れない現象について発明者が鋭意検討したところ、
（１）殺菌対象物が有する細菌が芽胞を形成する。
（２）その芽胞の形成状態が処理のタイミングにより異なる。
ことに起因していることを突き止めた。
Conventionally, there have been known methods for inactivating bacteria contained in objects such as foods and utensils and bacteria contained in beverages.
For example, a method for sterilizing powder using ozone is known. According to this sterilization method, since sterilization can be performed in a non-heated state, deterioration of the sterilized object can be suppressed.
However, in such a sterilization method, the reproducibility of sterilization may not be obtained. That is, even if the object to be sterilized is exposed to ozone to the same extent, the degree of sterilization may differ depending on the treatment.
When the inventor diligently examined the phenomenon that this sterilization cannot be reproduced,
(1) Bacteria contained in the sterilized object form spores.
(2) The formation state of the spores differs depending on the timing of treatment.
I found out that it was caused by that.
上記のような問題を解消するために、芽胞を一旦発芽（＝発芽誘導）させた後に殺菌処理することが考えられる。例えば、特開２００２－１５３２４７号公報（特許文献１）には、発芽誘導物質（Ｌ-アラニン）の水溶液を殺菌対象に噴霧し、その後オゾンや紫外線で殺菌処理することが記載されている。
また、特開２０１５－１９９７２３号公報（特許文献２）には、芽胞形成菌とジピコリン酸又はその塩とをｐＨ６以下の条件下で接触させることで、芽胞を一旦発芽させる方法が記載されている。
更には、特開平３－０３８８５７号公報（特許文献３）には、水分リッチな状態で、菌数の生育に適した温度（２０℃～４０℃）で数時間保持する方法が開示されている。
ところで、このような公知の発芽誘導方法では、化学物質（栄養物質）を使用したり、あるいは、長時間の処理が必要になったりするため、例えば食品の発芽誘導方法としては、不向きであり実用上好ましいものとはいえない。
In order to solve the above problems, it is conceivable that the spores are once germinated (= germination induction) and then sterilized. For example, Japanese Patent Application Laid-Open No. 2002-153247 (Patent Document 1) describes that an aqueous solution of a germination-inducing substance (L-alanine) is sprayed on a sterilization target and then sterilized with ozone or ultraviolet rays.
Further, Japanese Patent Application Laid-Open No. 2015-199723 (Patent Document 2) describes a method for temporarily germinating spores by contacting a spore-forming bacterium with dipicolinic acid or a salt thereof under a condition of pH 6 or less. ..
Further, Japanese Patent Application Laid-Open No. 3-038857 (Patent Document 3) discloses a method of holding a water-rich state at a temperature (20 ° C. to 40 ° C.) suitable for growing the number of bacteria for several hours. ..
By the way, such a known germination induction method uses a chemical substance (nutrient substance) or requires long-term treatment, and is therefore unsuitable and practical as a germination induction method for foods, for example. It cannot be said that it is preferable.
この発明は、上記従来技術の問題点に鑑みて、食品等の被処理物が有する芽胞形成菌を殺菌するにあたり、芽胞形成菌を発芽誘導させる方法において、化学物質を利用することなく、かつ、短時間で発芽させることができる発芽誘導方法およびこの発芽誘導方法を用いた殺菌方法を提供せんとするものである。 In view of the above-mentioned problems of the prior art, the present invention is a method for inducing germination of spore-forming bacteria in sterilizing spore-forming bacteria contained in an object to be treated such as food, without using a chemical substance and. It is intended to provide a germination induction method capable of germination in a short time and a sterilization method using this germination induction method.
上記課題を解決するために、この発明に係わる発芽誘導方法は、被処理物が有する芽胞形成菌に対して、波長７００ｎｍ～１０５０ｎｍにピーク波長を有する光を照射する工程を有することを特徴とする。
また、前記光は７５０ｎｍ～９７０ｎｍにピーク波長を有するものであることを特徴とする。
また、前記光の照射量が１．７Ｊ／ｃｍ２～２０１．２Ｊ／ｃｍ２であることを特徴とする。
また、前記光の照射量が３．４Ｊ／ｃｍ２～１３４．２Ｊ／ｃｍ２であることを特徴とする。
また、前記被処理物が固形物であり、当該被処理物における水分活性が０．７以上の状態で、前記芽胞形成菌に前記光を照射することを特徴とする。
また、前記光の照射中における前記被処理物の温度が、５℃～５０℃であることを特徴とする。
また、前記被処理物の殺菌方法において、前記発芽誘導方法からなる第一工程と、前記被処理物を殺菌処理する第二工程とを有することを特徴とする。
In order to solve the above problems, the germination induction method according to the present invention is characterized by having a step of irradiating the spore-forming bacteria contained in the object to be treated with light having a peak wavelength in the wavelength range of 700 nm to 1050 nm. ..
Further, the light is characterized by having a peak wavelength in the range of 750 nm to 970 nm.
Further, the irradiation amount of the light is 1.7 J / cm 2 to 2011.2 J / cm 2 .
Further, the irradiation amount of the light is 3.4 J / cm 2 to 134.2 J / cm 2 .
Further, the object to be treated is a solid substance, and the spore-forming bacteria are irradiated with the light in a state where the water activity in the object to be treated is 0.7 or more.
Further, the temperature of the object to be treated during irradiation with the light is 5 ° C to 50 ° C.
Further, the method for sterilizing the object to be treated is characterized by having a first step including the method for inducing germination and a second step for sterilizing the object to be treated.
この発明にかかる発芽誘導方法によれば、食品等の被処理物が有する芽胞形成菌を殺菌するにあたり、化学物質（栄養物質）を使用することなく芽胞形成菌を短時間で発芽誘導できるので、殺菌処理後に化学物質が残存することがなく、不活化しきれなかった菌が、保管中に増殖するリスクを低減できる。
そして、食品等が有する細菌が発芽した状態で殺菌処理されるので、殺菌処理後の細菌の不活化の程度におけるバラツキが低減する。
According to the germination induction method according to the present invention, in sterilizing the spore-forming bacteria contained in the object to be treated such as food, the spore-forming bacteria can be induced to germinate in a short time without using a chemical substance (nutrient substance). No chemical substances remain after the sterilization treatment, and the risk of growth of bacteria that could not be inactivated during storage can be reduced.
Then, since the sterilization treatment is performed in the state where the bacteria possessed by the food or the like are germinated, the variation in the degree of inactivation of the bacteria after the sterilization treatment is reduced.
本発明の発芽誘導方法を用いた殺菌方法のフロー図の一例が図1に示されている。この実施例では、殺菌対象である被処理物は、食品、例えば、ブラックペッパーなどの固形物である。
被処理物の表面には芽胞形成菌が付着しており、この芽胞形成菌を発芽させて後続のオゾンによる殺菌を効果的なものとするものである。
そのプロセスが図1に示されている。
＜水分賦活工程＞
殺菌対象である食品（ブラックペッパー）を純水に浸漬する工程である。この工程は芽胞を発芽させる際に必要となる水分活性を付与するために行われる。この工程は、水分活性が一定以上ある状態でないと、次工程で近赤外光を照射しても十分に発芽しない、という知見に基づく処理である。
ここで、水分活性とは、被処理物である食品中の自由水の割合を示す数値で、食品の保存性の指標とされる。この水分活性は、アズワン社の水分活性測定器（ＳＰ－Ｗ）を使用して測定した。
また、水分賦活処理としては、上記純水への浸漬以外に、加湿空気の噴霧、ミストエアロゾルの噴霧、水の噴霧などの手段が採用できる。
An example of a flow chart of a sterilization method using the germination induction method of the present invention is shown in FIG. In this embodiment, the object to be sterilized is a food product, for example, a solid substance such as black pepper.
Spore-forming bacteria are attached to the surface of the object to be treated, and the spore-forming bacteria are germinated to make subsequent sterilization with ozone effective.
The process is shown in Figure 1.
<Moisture activation process>
This is a process of immersing food (black pepper) to be sterilized in pure water. This step is performed to impart the water activity required for germination of spores. This step is a process based on the finding that germination does not occur sufficiently even if near-infrared light is irradiated in the next step unless the water activity is above a certain level.
Here, the water activity is a numerical value indicating the ratio of free water in the food to be treated, and is used as an index of food preservation. This water activity was measured using a water activity measuring instrument (SP-W) manufactured by AS ONE Corporation.
Further, as the water activation treatment, in addition to the immersion in pure water, means such as spraying humidified air, spraying mist aerosol, and spraying water can be adopted.
＜発芽誘導工程＞
殺菌対象である食品に近赤外光を照射して、食品に付着した芽胞形成菌を発芽させる工程である。
照射近赤外光の波長としては、７００ｎｍ～１０５０ｎｍのものが利用できる。本実施形態においては、波長８５０ｎｍにピーク波長を有する近赤外光を発するＬＥＤを光源としている。なお、光源としては、ＬＥＤ以外にハロゲンランプなどを用いることもできる。
ただし、近赤外光を照射しているとき、被処理物の温度が５℃～５０℃の範囲にあることが好ましい。この範囲外であるとき、芽胞の発芽効率が低下する惧れがある。近赤外光を照射しているときに上記の温度範囲となるようにする方法としては、被処理物に照射される光に被処理物が吸収する波長の光が含まれないようにする方法や、光源を間欠的に点灯させて被処理物の温度上昇を防ぐ方法が採用され得る。光源としてＬＥＤを用いる構成は、被処理物に照射される光に被処理物が吸収する波長の光が含まれない状態とすることが容易であるため好ましい。
また、この近赤外光を放射する光源としては、波長４００ｎｍ以下の光（紫外光）を放射しないものであることが好ましい。この範囲の紫外光を放射するものでは、近赤外光と紫外光が同時に照射されてしまい、芽胞の発芽効率が低下してしまう惧れがある。
更には、被処理物への近赤外光の照射量は、１．７Ｊ／ｃｍ２～１３４．２Ｊ／ｃｍ２の範囲であることが好ましく、より好適には、３．４３Ｊ／ｃｍ２～１３４．２Ｊ／ｃｍ２の範囲であることが更に好ましく、これより少なすぎたり多すぎたりすると発芽が効果的に行われない。
<Germination induction process>
This is a step of irradiating the food to be sterilized with near-infrared light to germinate the spore-forming bacteria attached to the food.
As the wavelength of the irradiated near-infrared light, those having a wavelength of 700 nm to 1050 nm can be used. In the present embodiment, an LED that emits near-infrared light having a peak wavelength at a wavelength of 850 nm is used as a light source. As the light source, a halogen lamp or the like can be used in addition to the LED.
However, when irradiating with near infrared light, the temperature of the object to be treated is preferably in the range of 5 ° C to 50 ° C. When it is out of this range, the germination efficiency of spores may decrease. As a method of keeping the temperature within the above temperature range when irradiating near-infrared light, a method of preventing the light irradiated to the object to be processed from including the light having a wavelength absorbed by the object to be processed. Alternatively, a method of intermittently turning on the light source to prevent the temperature of the object to be processed from rising can be adopted. A configuration using an LED as a light source is preferable because it is easy to make the light irradiating the object to be processed not include light having a wavelength absorbed by the object to be processed.
Further, as the light source that radiates this near-infrared light, it is preferable that the light source does not radiate light having a wavelength of 400 nm or less (ultraviolet light). Those that emit ultraviolet light in this range may be irradiated with near-infrared light and ultraviolet light at the same time, and the germination efficiency of spores may decrease.
Further, the irradiation amount of near-infrared light on the object to be treated is preferably in the range of 1.7 J / cm 2 to 134.2 J / cm 2 , and more preferably 3.43 J / cm 2 to. It is more preferably in the range of 134.2 J / cm 2 , and if it is too small or too large, germination will not be effective.
＜殺菌工程＞
殺菌対象である食品に殺菌処理を施す工程であって、本実施形態では、前記発芽誘導工程で発芽した芽胞形成菌を有する被処理物をオゾンに曝すことによって殺菌処理するオゾン殺菌処理を採用している。
殺菌手段としては、殺菌対象の食品の劣化を抑制する観点から、殺菌対象の温度が上がらないものが好ましく、上記オゾン殺菌や、紫外線照射による殺菌などが挙げられる。
<Sterilization process>
This is a step of sterilizing a food to be sterilized, and in the present embodiment, an ozone sterilization treatment is adopted in which an object to be treated having spore-forming bacteria germinated in the germination induction step is sterilized by exposing it to ozone. ing.
As the sterilization means, from the viewpoint of suppressing deterioration of the food to be sterilized, it is preferable that the temperature of the sterilization target does not rise, and examples thereof include ozone sterilization and sterilization by ultraviolet irradiation.
上記実施例は、殺菌対象が例えば、ブラックペッパーなどの固形物であるが、本発明の発芽誘導方法は液体にも適用できる。例えば、オレンジジュースなどの果汁飲料にも適用できる。
図２には、殺菌対象が液体の場合の発芽誘導方法と殺菌方法のフローが示されている。
＜発芽誘導工程＞
殺菌対象である果汁飲料などの液体状食品に近赤外光を照射して、液体中に含まれる芽胞形成菌を発芽させる工程であって、本実施形態では液体に近赤外光を照射する。この時の近赤外光の詳細は図1における近赤外光と同様である。
In the above embodiment, the sterilization target is a solid substance such as black pepper, but the germination induction method of the present invention can also be applied to a liquid. For example, it can be applied to fruit juice beverages such as orange juice.
FIG. 2 shows the flow of the germination induction method and the sterilization method when the sterilization target is a liquid.
<Germination induction process>
It is a step of irradiating a liquid food such as a fruit juice beverage to be sterilized with near-infrared light to germinate spore-forming bacteria contained in the liquid, and in the present embodiment, the liquid is irradiated with near-infrared light. .. The details of the near-infrared light at this time are the same as those of the near-infrared light in FIG.
＜殺菌工程＞
殺菌対象である液体状食品に殺菌処理を施す工程であって、本実施形態では、前記発芽誘導工程で発芽した芽胞形成菌に紫外光（ＵＶ）を照射して殺菌する方法を採用している。殺菌対象が果汁飲料などのように風味が重要なものである場合には、波長２８０ｎｍ～３００ｎｍの紫外光（ＵＶ）が好適に利用される。この紫外光殺菌により、風味の劣化を招くことなく殺菌処理を効果的に行うことができる。
このような紫外光光源としては、発光ガスとしてＸｅＢｒが封入されたエキシマランプなどが利用でき、本実施形態では、ピーク波長２８３ｎｍの紫外光を放射するＸｅＢｒエキシマランプを使用している。
<Sterilization process>
This is a step of sterilizing a liquid food to be sterilized, and in the present embodiment, a method of sterilizing the spore-forming bacteria germinated in the germination induction step by irradiating them with ultraviolet light (UV) is adopted. .. When the sterilization target is a fruit juice beverage or the like in which flavor is important, ultraviolet light (UV) having a wavelength of 280 nm to 300 nm is preferably used. By this ultraviolet light sterilization, the sterilization treatment can be effectively performed without causing deterioration of the flavor.
As such an ultraviolet light source, an excimer lamp or the like in which XeBr is enclosed as a light emitting gas can be used, and in the present embodiment, an XeBr excimer lamp that emits ultraviolet light having a peak wavelength of 283 nm is used.
次に、各種条件をパラメータとして実験を行った。
まず、殺菌対象サンプルとして未殺菌状態の黒コショウ（ブラックペッパー）（産地：マレーシア）を用意した。なお、以下の実験で使用する黒コショウは、その表面に汚れや微粒子などが付着していない状態であることが確認されたものを使用した。
１．サンプルを純水に１０分間浸漬した（水分賦活工程）。
２．１を真空乾燥装置（ＤＰ２００、ヤマト科学社製）に入れ、２５℃、０．１ｋＰａの条件で乾燥させた（時間を調整することでサンプルの水分活性を調整した）。
３．２のサンプルに対してＬＥＤからの近赤外光を照射した（発芽誘導工程）。
具体的には、２のサンプルを殺菌ガラスシャーレ（直径３５ｍｍ）に１ｇ入れ、このシャーレを振動器に載せて振動させた状態で、照射装置からの光を照射した。なお、シャーレ内に照射される光の照度が照射面内において一定となるように、サンプルに対して近赤外光を照射した。
ここで、本発明における「照度」とは、被処理物に対して照射される光のうち、波長が３００ｎｍ～１２００ｎｍの範囲にある光の、単位面積あたり強度のことをいう。
４．３のサンプルを、オゾン条件１７０ｐｐｍ一定で６時間、オゾン処理した（殺菌工程）。具体的には、２のサンプルを滅菌ガラスシャーレ（直径３５ｍｍ）に１ｇ入れ、このシャーレを振動器に載せて振動させた状態で、１７０ｐｐｍのオゾンに６時間曝露した。
５．４のサンプルを滅菌水１００ｍＬに浸漬して、サンプルに付着している菌を滅菌水に移した。
６．５の菌抽出液１ｍＬをとり、このうち０．１ｍＬを寒天培地に塗布した。
７．６の寒天培地を３７℃で２４時間培養した。
８．７の寒天培地に発生しているコロニーの数を数えた。
Next, experiments were conducted with various conditions as parameters.
First, unsterilized black pepper (black pepper) (produced in Malaysia) was prepared as a sample to be sterilized. The black pepper used in the following experiments was confirmed to have no dirt or fine particles on its surface.
1. 1. The sample was immersed in pure water for 10 minutes (moisture activation step).
2.1 was placed in a vacuum dryer (DP200, manufactured by Yamato Kagaku Co., Ltd.) and dried under the conditions of 25 ° C. and 0.1 kPa (the water activity of the sample was adjusted by adjusting the time).
The sample of 3.2 was irradiated with near-infrared light from the LED (germination induction step).
Specifically, 1 g of the sample 2 was placed in a sterilized glass petri dish (diameter 35 mm), and the petri dish was placed on a vibrator and vibrated, and then irradiated with light from an irradiation device. The sample was irradiated with near-infrared light so that the illuminance of the light irradiated in the petri dish was constant in the irradiation surface.
Here, the "illuminance" in the present invention means the intensity per unit area of the light having a wavelength in the range of 300 nm to 1200 nm among the light irradiated to the object to be treated.
The sample of 4.3 was ozone-treated for 6 hours under constant ozone conditions of 170 ppm (sterilization step). Specifically, 1 g of the sample 2 was placed in a sterile glass petri dish (diameter 35 mm), and the petri dish was placed on a vibrator and vibrated, and then exposed to 170 ppm ozone for 6 hours.
The sample of 5.4 was immersed in 100 mL of sterile water, and the bacteria adhering to the sample were transferred to the sterile water.
1 mL of the bacterial extract of 6.5 was taken, and 0.1 mL of this was applied to the agar medium.
The 7.6 agar medium was cultured at 37 ° C. for 24 hours.
The number of colonies occurring on the 8.7 agar medium was counted.
以上の実験を、以下のパラメータごとに行った。
＜近赤外光の波長をパラメータとしたときの実験＞
１．近赤外光の照射条件
・光源：ＬＥＤ
・照度：５５．９ｍＷ／ｃｍ２
・照射時間：６００秒
２．その他の光照射時の条件
・水分活性：０．９
・環境温度：２４．５℃
・サンプル温度：３０．０℃
３．オゾン殺菌条件
・オゾン濃度：１７０ｐｐｍ
・処理時間：６時間
The above experiment was performed for each of the following parameters.
<Experiment when the wavelength of near infrared light is used as a parameter>
1. 1. Irradiation conditions for near-infrared light ・ Light source: LED
・ Illuminance: 55.9mW / cm 2
-Irradiation time: 600 seconds 2. Other conditions for light irradiation ・ Water activity: 0.9
・ Environmental temperature: 24.5 ℃
-Sample temperature: 30.0 ° C
3. 3. Ozone sterilization conditions ・ Ozone concentration: 170ppm
・ Processing time: 6 hours
その結果が図３の表１に示されている。表中の各項目は以下のとおりである。
・ピーク波長：ＬＥＤが放射する光のピーク波長
・オゾン処理後菌数ＣＦＵ／ｇ：サンプル（黒コショウ）１ｇ中に存在する菌の数で、少ないほど良好。
・殺菌率：オゾン処理後の菌数がオゾン処理前と比較してどの程度減ったかを示す数値。
ｌｏｇ（オゾン処理後菌数／オゾン処理前菌数）で計算する。処理前の菌数より処理後の菌数が小さくなればマイナスの値をとり、処理前の菌数より処理後の菌数が大きくなればプラスの値をとる。値が小さいほど良好。
また、実施例１～７における照射光の分光スペクトルをそれぞれ図４～１０に示す。（実施例４における照射光の分光スペクトルは図７において実線で示されている。）
The results are shown in Table 1 of FIG. Each item in the table is as follows.
-Peak wavelength: Peak wavelength of light emitted by LED-Number of bacteria after ozone treatment CFU / g: The number of bacteria present in 1 g of sample (black pepper), the smaller the number, the better.
-Sterilization rate: A numerical value indicating how much the number of bacteria after ozone treatment has decreased compared to before ozone treatment.
Calculated by log (number of bacteria after ozone treatment / number of bacteria before ozone treatment). If the number of bacteria after treatment is smaller than the number of bacteria before treatment, a negative value is taken, and if the number of bacteria after treatment is larger than the number of bacteria before treatment, a positive value is taken. The smaller the value, the better.
Further, the spectral spectra of the irradiation light in Examples 1 to 7 are shown in FIGS. 4 to 10, respectively. (The spectral spectrum of the irradiation light in Example 4 is shown by a solid line in FIG. 7.)
表１に示すように、光照射しない比較例１と比較して、近赤外光を照射する実施例１～７はいずれも殺菌の程度が大きいことが分かる。つまり、この実験で用いたピーク波長７００ｎｍ～１０５０ｎｍの近赤外光照射処理は、いずれも芽胞の発芽を誘導しており、その後の殺菌処理を効果的にしていることが分かる。
とりわけ、実施例１、７に比較して、実施例２～６はいずれも殺菌の程度がさらに大きく、このことから、特に、ピーク波長７００ｎｍ～９７０ｎｍの光源を用いることにより、芽胞の発芽をより効率よく誘導できることが分かる。
As shown in Table 1, it can be seen that the degree of sterilization is higher in all of Examples 1 to 7 irradiated with near-infrared light as compared with Comparative Example 1 not irradiated with light. That is, it can be seen that the near-infrared light irradiation treatment with a peak wavelength of 700 nm to 1050 nm used in this experiment induces germination of spores, and the subsequent sterilization treatment is effective.
In particular, the degree of sterilization in all of Examples 2 to 6 is larger than that in Examples 1 and 7, and from this, in particular, by using a light source having a peak wavelength of 700 nm to 970 nm, germination of spores can be further enhanced. It can be seen that it can be guided efficiently.
次に、近赤外光の照射量をパラメータとした実験を行った。
＜近赤外光の照射量（照射時間）をパラメータとしたときの実験＞
１．近赤外光の照射条件
・光源：ＬＥＤ
・ピーク波長：８５０ｎｍ（分光スペクトルは図７において実線で示したものと同じ）
・照度：５５．９ｍＷ／ｃｍ２
２．その他の光照射時の条件
・水分活性：０．９
・環境温度：２４．１℃
・サンプル温度：３０．０℃
３．オゾン殺菌条件
・オゾン濃度：１７０ｐｐｍ
・処理時間：６時間
Next, an experiment was conducted with the irradiation amount of near-infrared light as a parameter.
<Experiment when the irradiation amount (irradiation time) of near-infrared light is used as a parameter>
1. 1. Irradiation conditions for near-infrared light ・ Light source: LED
-Peak wavelength: 850 nm (spectral spectrum is the same as that shown by the solid line in FIG. 7)
・ Illuminance: 55.9mW / cm 2
2. 2. Other conditions for light irradiation ・ Water activity: 0.9
-Environmental temperature: 24.1 ° C
-Sample temperature: 30.0 ° C
3. 3. Ozone sterilization conditions ・ Ozone concentration: 170ppm
・ Processing time: 6 hours
その結果が図１１の表２に示されている。
比較例１と比較して、実施例８～１６は、いずれも殺菌の程度が大きく、照射量０．６Ｊ／ｃｍ２～２０１．２Ｊ／ｃｍ２の近赤外光は、いずれも芽胞の発芽を誘導しており、その後の殺菌処理を効果的にしていることが分かる。
また、実施例８と比較して、実施例９～１６はいずれも殺菌の程度がさらに大きく、このことから、特に、近赤外光の照射量を１．７Ｊ／ｃｍ２～２０１．２Ｊ／ｃｍ２とすることにより、芽胞の発芽を効率良く誘導できることが分かる。
さらに、実施例８、９、１６と比較して、実施例１０～１５はいずれも殺菌の程度がさらに大きく、このことから、特に、近赤外光の照射量を３．４Ｊ／ｃｍ２～１３４．２Ｊ／ｃｍ２とすることにより、芽胞の発芽を効率良く誘導できることが分かる。
なお、後述する実験の結果により、照度を変えた場合においても、照射量が同じであれば同様の効率で発芽を誘導できることが分かる。
The results are shown in Table 2 of FIG.
Compared with Comparative Example 1, in Examples 8 to 16, the degree of sterilization was large, and near-infrared light having an irradiation dose of 0.6 J / cm 2 to 2001.2 J / cm 2 all caused spore germination. It can be seen that the subsequent sterilization treatment is effective.
Further, as compared with Example 8, the degree of sterilization is further greater in all of Examples 9 to 16, and therefore, in particular, the irradiation amount of near-infrared light is 1.7 J / cm 2 to 2001.2 J /. It can be seen that the germination of spores can be efficiently induced by setting the size to cm 2 .
Further, as compared with Examples 8, 9 and 16, the degree of sterilization is further greater in all of Examples 10 to 15, and therefore, in particular, the irradiation amount of near infrared light is 3.4 J / cm 2 to. It can be seen that the germination of spores can be efficiently induced by setting 134.2 J / cm 2 .
From the results of the experiments described later, it can be seen that germination can be induced with the same efficiency even when the illuminance is changed if the irradiation amount is the same.
次に、水分活性をパラメータとした実験を行った。
＜水分活性をパラメータとしたときの実験＞
１．近赤外光の照射条件
・光源：ＬＥＤ
・ピーク波長：８５０ｎｍ（分光スペクトルは図７において実線で示したものと同じ）
・照度：５５．９ｍＷ／ｃｍ２
・照射時間：６００秒
２．その他の光照射時の条件
・環境温度：２４．３℃
・サンプル温度：３０．０℃
３．オゾン殺菌条件
・オゾン濃度：１７０ｐｐｍ
・処理時間：６時間
Next, an experiment was conducted with water activity as a parameter.
<Experiment with water activity as a parameter>
1. 1. Irradiation conditions for near-infrared light ・ Light source: LED
-Peak wavelength: 850 nm (spectral spectrum is the same as that shown by the solid line in FIG. 7)
・ Illuminance: 55.9mW / cm 2
-Irradiation time: 600 seconds 2. Other conditions for light irradiation ・ Environmental temperature: 24.3 ° C
-Sample temperature: 30.0 ° C
3. 3. Ozone sterilization conditions ・ Ozone concentration: 170ppm
・ Processing time: 6 hours
その結果が図１２の表３に示されている。
比較例１と比較して、実施例１７～２３は、いずれも殺菌の程度が大きく、水分活性０．４～１．０のサンプル対する近赤外光照射はいずれも芽胞の発芽を誘導しており、その後の殺菌処理を効果的にしていることが分かる。
とりわけ、実施例１７～１９と比較して、実施例２０～２３はいずれも殺菌の程度がさらに大きく、このことから、特に、サンプルの水分活性を０．７～１．０とすることにより、芽胞の発芽を効率良く誘導できることが分かる。
The results are shown in Table 3 of FIG.
Compared with Comparative Example 1, in Examples 17 to 23, the degree of sterilization was large, and irradiation with near-infrared light for a sample having a water activity of 0.4 to 1.0 induced germination of spores. It can be seen that the subsequent sterilization treatment is effective.
In particular, the degree of sterilization was even greater in all of Examples 20 to 23 as compared with Examples 17 to 19, and from this, in particular, by setting the water activity of the sample to 0.7 to 1.0, It can be seen that the germination of spores can be efficiently induced.
次に、サンプル温度をパラメータとした実験を行った。
＜近赤外光照射時のサンプル温度をパラメータとした実験＞
１．近赤外光の照射条件
・光源：ＬＥＤ
・ピーク波長：８５０ｎｍ（分光スペクトルは図７において実線で示したものと同じ）
・照度：５５．９ｍＷ／ｃｍ２
・照射時間：６００秒
２．その他の光照射時の条件
・水分活性：０．９
・環境温度：２４．５℃
３．オゾン殺菌条件
・オゾン濃度：１７０ｐｐｍ
・処理時間：６時間
Next, an experiment was conducted with the sample temperature as a parameter.
<Experiment using sample temperature during near-infrared light irradiation as a parameter>
1. 1. Irradiation conditions for near-infrared light ・ Light source: LED
-Peak wavelength: 850 nm (spectral spectrum is the same as that shown by the solid line in FIG. 7)
・ Illuminance: 55.9mW / cm 2
-Irradiation time: 600 seconds 2. Other conditions for light irradiation ・ Water activity: 0.9
・ Environmental temperature: 24.5 ℃
3. 3. Ozone sterilization conditions ・ Ozone concentration: 170ppm
・ Processing time: 6 hours
その結果が図１３の表４に示されている。なお、近赤外光照射時のサンプル温度は、サンプルを収納した筐体を加熱することで当該温度となるように調整した。近赤外光照射では、サンプルが上記波長の光を殆ど吸収しないので、温度が殆ど上昇しないためである。
比較例１と比較して、実施例２４～３０は、いずれも殺菌の程度が大きく、温度５℃～５５℃のサンプルに対する近赤外光照射はいずれも芽胞の発芽を誘導しており、その後の殺菌処理を効果的にしていることが分かる。
とりわけ、実施例３０と比較して、実施例２４～２９はいずれも殺菌の程度がさらに大きく、このことから、特に、近赤外光照射時のサンプルの温度を５℃～５０℃とすることにより、芽胞の発芽を効率良く誘導できることが分かる。
また、近赤外光照射時のサンプルの温度が５０℃以下であることが確認されているので、従来公知の殺菌方法、特に、ハロゲンヒータやキセノンランプを点灯照射する殺菌方法とは異なる作用であることが分かる。
The results are shown in Table 4 of FIG. The sample temperature at the time of irradiation with near-infrared light was adjusted so as to reach the temperature by heating the housing containing the sample. This is because in near-infrared irradiation, the sample hardly absorbs the light having the above wavelength, so that the temperature hardly rises.
Compared with Comparative Example 1, in Examples 24 to 30, the degree of sterilization was large, and irradiation with near-infrared light on a sample having a temperature of 5 ° C to 55 ° C all induced germination of spores. It can be seen that the sterilization treatment of is effective.
In particular, the degree of sterilization in all of Examples 24 to 29 is higher than that in Example 30, and therefore, in particular, the temperature of the sample at the time of near-infrared light irradiation is set to 5 ° C to 50 ° C. Therefore, it can be seen that the germination of spores can be efficiently induced.
Further, since it has been confirmed that the temperature of the sample at the time of near-infrared light irradiation is 50 ° C. or lower, the action is different from the conventionally known sterilization method, particularly the sterilization method of lighting and irradiating a halogen heater or a xenon lamp. It turns out that there is.
次に、照射量が同じ、且つ照度が異なる照射条件である場合に、殺菌率の差が生じるか確認するための実験を行った。
１．近赤外光の照射条件
・光源：ＬＥＤ
・ピーク波長：８５０ｎｍ
２．その他の光照射時の条件
・水分活性：０．９
・環境温度：２４．５℃
３．オゾン殺菌条件
・オゾン濃度：１７０ｐｐｍ
・処理時間：６時間
Next, an experiment was conducted to confirm whether or not a difference in sterilization rate occurs when the irradiation amount is the same and the illuminance is different.
1. 1. Irradiation conditions for near-infrared light ・ Light source: LED
-Peak wavelength: 850 nm
2. 2. Other conditions for light irradiation ・ Water activity: 0.9
・ Environmental temperature: 24.5 ℃
3. 3. Ozone sterilization conditions ・ Ozone concentration: 170ppm
・ Processing time: 6 hours
その結果が図１４の表５に示されている。なお、実施例３１、３４、３７の分光スペクトルは図７において実線で、実施例３２、３５、３８の分光スペクトルは図７において点線で、実施例３３、３６、３９の分光スペクトルは図７において破線で示されている。
実施例３１～３３、実施例３４～３６、実施例３７～３９の各群において、殺菌率が同一群内で同じであることが分かる。つまり、照度を変えた場合においても、照射量が同じであれば同様の効率で発芽を誘導できることが分かる。
The results are shown in Table 5 of FIG. The spectral spectra of Examples 31, 34, and 37 are solid lines in FIG. 7, the spectral spectra of Examples 32, 35, and 38 are dotted lines in FIG. 7, and the spectral spectra of Examples 33, 36, and 39 are shown in FIG. It is shown by a broken line.
It can be seen that in each group of Examples 31 to 33, Examples 34 to 36, and Examples 37 to 39, the sterilization rate is the same within the same group. That is, it can be seen that even when the illuminance is changed, germination can be induced with the same efficiency if the irradiation amount is the same.
以上説明したように、本発明に係る発芽誘導方法によれば、被処理物が有する芽胞形成菌に対して、波長７００ｎｍ～１０５０ｎｍにピーク波長を有する近赤外光を照射する工程を有することにより、化学物質（栄養物質）を使用することなく短時間で芽胞形成菌を発芽誘導できるので、殺菌処理後に化学物質が残存することがなく、不活化しきれなかった菌が、保管中に増殖するリスクを低減できる。
また、食品等が有する細菌が発芽した状態で効果的に殺菌処理されるので、殺菌処理後の細菌の不活化の程度におけるバラツキが低減する。
As described above, according to the germination induction method according to the present invention, the spore-forming bacteria contained in the object to be treated are irradiated with near-infrared light having a peak wavelength in the wavelength range of 700 nm to 1050 nm. Since germination of spore-forming bacteria can be induced in a short time without using chemical substances (nutrients), chemical substances do not remain after sterilization treatment, and bacteria that could not be inactivated grow during storage. Risk can be reduced.
In addition, since the bacteria contained in food or the like are effectively sterilized in a germinated state, the variation in the degree of inactivation of the bacteria after the sterilization treatment is reduced.
Claims (6)
A sterilization method comprising a first step comprising the germination induction method according to claim 1 and a second step of sterilizing the object to be treated.
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| BR0106707A (en) * | 2000-05-30 | 2002-07-23 | Hoshin Kagaku Sangyosho Kk | Method for sterilizing fungi and / or bacteria in a spore state, and sterilizing against fungi and / or bacteria in a spore state |
| JP4872048B2 (en) * | 2007-11-14 | 2012-02-08 | 株式会社あじかん | Method for germinating spores and method for sterilizing spores using the same |
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| Title |
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| International Biodeterioration & Biodegradation, 2009, Vol.63, pp.196-200 |
| Journal of Biological Engineering, 2013, Vol.7, Article No.19 (pp.1-12) |
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