WO2019131869A1 - Food sterilization method - Google Patents

Abstract

A food sterilization method having a holding step 12 in which a mixture 3 including food 1, organic acid, sugar, and ethanol or a mixture including ethanol 2 and food 1 including organic acid and sugar is held at no more than –10ºC. The ethanol 2 content in the mixture 3 is 0.08–8 wt%. The food 1 is at least one type selected from fruit, fruit juice, and vegetables.

Description

Food sterilization method

The present invention relates to a method of sterilizing food.

Food and drink generally cause problems such as food poisoning due to the contamination of harmful microorganisms. In addition, during storage and transportation of products such as food and drink, unintended changes in the flavor and aroma of the product may occur due to the occurrence of unintended fermentation by the producer due to the action of microorganisms. Furthermore, in the case where the product is packaged in a sealed state, the internal pressure of the container is increased by carbon dioxide generated during fermentation, which may lead to breakage of the container. Therefore, in the manufacture of products such as food and drink, a method of killing the microorganisms present in the food and drink and the like, that is, a sterilization method is required.

As a method of sterilizing microorganisms present in food and drink and the like, a method by heating and a method by food additives having a bactericidal action have been used conventionally. However, these methods may impair or change the flavor and aroma originally possessed by foods and the like. Therefore, sterilization methods without heating and a large amount of additives have been studied.

As such a sterilization method, for example, Japanese Patent Application Laid-Open No. 5-328950 (Patent Document 1) is a sterilization method for food and drink subjected to pressure (high pressure) treatment in a temperature range from normal pressure antifreeze temperature to 15 ° C. It is disclosed. According to the said method, it can suppress that the quality of food-drinks changes by the heating for sterilization.

Japanese Patent Application Laid-Open No. 58-170471 (Patent Document 2) discloses a method of sterilizing brewed liquor by rapid freezing. According to the said method, since microorganisms, such as a blight fungus, can be disinfected without being accompanied by a burning process, it can suppress that the original flavor which brewing liquor has changes.

Japanese Patent Application Laid-Open No. 5-328950 Japanese Patent Application Laid-Open No. 58-170471

However, adopting a method requiring special equipment for pressurization or cryogenic temperature may increase the manufacturing cost. For example, the method described in Patent Document 1 requires special equipment to pressurize, which may increase the cost required to install, operate, and maintain the equipment. Further, the method described in Patent Document 2 exemplifies dry ice-acetone (−70 ° C.) and liquid nitrogen (−140 ° C.) as cooling means because it is rapidly frozen. That is, the implementation of the method requires special freezing equipment to achieve a cryogenic temperature of -70 ° C. or less, which may also increase the cost.

In view of the above problems, it is desired to realize a sterilization method that does not involve heating, and that can be implemented at low cost without requiring special equipment.

The method for sterilizing food according to the present invention maintains a mixture containing food, organic acid, sugar and ethanol, or a food containing organic acid and sugar, and a mixture containing ethanol at -10 ° C or less Holding step, the content of ethanol in the mixture is 0.08 to 8% by weight, and the food is at least one food selected from fruits, fruit juices, and vegetables. I assume.

According to this sterilizing method, since the bactericidal effects of organic acids, sugars and ethanol can be used additively, a sterilizing method without heating can be realized without using a pressure device. . In addition, when the temperature of the holding step is in the above-mentioned range, sterilization can be performed using a general freezing storage or equipment used for freezing transportation. That is, neither pressure equipment nor cryogenic equipment is required. Furthermore, because the equipment is common, sterilization can be performed simultaneously while storing or transporting the food to be sterilized. Therefore, the new equipment for the sterilization process does not require a separate period, and both the equipment and the period are efficient, and sterilization can be performed at low cost.

Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited by the examples of preferred embodiments described below.

In one aspect, the holding step is preferably within 100 hours.

According to this configuration, since the holding process can be performed for a relatively short time, power consumption for maintaining the low temperature can be reduced, and the cost can be reduced. In addition, since the time required for the sterilization process can be made relatively short, the manufacturing process can be shortened.

In one embodiment, the content of the organic acid in the mixture is preferably 0.01 to 10% by weight.

According to this configuration, the bactericidal effect of the present invention can be further enhanced.

In one embodiment, it is preferred that the organic acid is citric acid.

According to this configuration, the bactericidal effect of the present invention can be further enhanced. In addition, when the food-based product to be sterilized by the sterilization method of the present invention contains citric acid, the citric acid added for sterilization can be used as part of the product, so the citric acid is removed There is no need to provide

In one embodiment, the content of sugar in the mixture is preferably 1 to 10% by weight.

According to this configuration, the bactericidal effect of the present invention can be further enhanced.

In one embodiment, the sugar is preferably at least one sugar selected from sucrose and fructose.

According to this configuration, the bactericidal effect of the present invention can be further enhanced. In addition, when the food sterilized by the sterilization method of the present invention and the product made from the food both contain sucrose or fructose, sucrose or fructose added for sterilization is a product of Since it is available as a part, there is no need to provide a step for removing the sucrose or fructose.

ADVANTAGE OF THE INVENTION According to this invention, it is the sterilization method which does not accompany heating, Comprising: The sterilization method which can be implemented at low cost and in a short period of time is realized without requiring special equipment. According to this sterilizing method, there is no risk of impairing the flavor and aroma originally possessed by food and drink and the like, which contributes to the production of a food having both safety and high quality.

Further features and advantages of the invention will become more apparent from the following description of exemplary and non-limiting embodiments.

The flow figure showing one embodiment of the sterilization method concerning the present invention.

Embodiments of the method of sterilizing food according to the present invention will be described in detail with reference to the drawings.

The following embodiment demonstrates the example which applied the disinfection method of the foodstuff which concerns on this invention to the disinfection of the fruit juice 1 which is an example of the foodstuff used as a raw material of an alcoholic beverage. In the method of sterilizing food according to this embodiment, as shown in FIG. 1, mixing step 11 in which ethanol 2 is added to fruit juice 1 and mixed, and holding step 12 in which mixture 3 obtained in mixing step 11 is held at low temperature And. The fruit juice 1 sterilized through these steps is sent to the subsequent step (not shown) of producing an alcoholic beverage.

First, a mixing step 11 for obtaining a mixture 3 containing fruit juice 1 and ethanol 2 is performed. The fruit juice 1 contains citric acid, sucrose and water. As the mixing step 11, a known mixing method can be used. For example, it may be a method of charging the above-mentioned respective materials into a mixing tank provided with a stirring blade and rotating the stirring blade to mix these materials. In addition, the content rate of ethanol 2, a citric acid, and sucrose which are contained in the mixture 3 obtained by the mixing process 11 can be controlled by selecting the quantity of each raw material thrown in the mixing process 11 suitably.

The content of ethanol 2 in the mixture 3 is preferably 0.08 to 8% by weight. When the content of ethanol 2 is in the above range, a good bactericidal effect can be obtained. The content of ethanol 2 is more preferably 0.8 to 8% by weight, and still more preferably 4 to 8% by weight. In addition, since the mixture 3 contains the ethanol 2 and the water which fruit juice 1 contains, it has the property as an ethanol aqueous solution.

The content of citric acid in the mixture 3 is preferably 0.01 to 10% by weight. When the content of citric acid is in the above range, the bactericidal effect can be further enhanced. The content of citric acid is more preferably 0.01 to 10% by weight, and still more preferably 1 to 10% by weight. At this time, citric acid may be mixed with the fruit juice 1 in the mixing step 11 so that the content of citric acid in the mixture 3 falls within a suitable range. In addition, since it is an additive which brings about a bactericidal effect and is also a raw material of the alcoholic beverage manufactured, it is not necessary to provide the process which removes citric acid.

The sucrose content in mixture 3 is preferably 1 to 10% by weight. When the sucrose content is in the above range, the bactericidal effect can be further enhanced. The sucrose content is more preferably 5 to 10% by weight, and still more preferably 8 to 10% by weight.
At this time, sucrose may be mixed with the fruit juice 1 in the mixing step 11 so that the content of sucrose in the mixture 3 falls within a suitable range. In addition, since sucrose is an additive which brings about a bactericidal effect and is also a raw material of manufactured alcoholic beverages, it is not necessary to provide the process of removing sucrose.

The pH of the mixture 3 is not particularly limited, but may be less than 5.0, preferably less than 3.5, and more preferably less than 2.5.

Next, the holding step 12 of holding the mixture 3 obtained by the mixing step 11 at a low temperature is performed.
A well-known thing can be used for the cooling installation which concerns on the holding process 12. FIG. For example, it may be a frozen storage facility or a frozen transportation facility.

The holding temperature in the holding step 12 is preferably −10 ° C. or less. When the holding temperature is −10 ° C. or less, a good bactericidal effect can be obtained. The holding temperature is more preferably −15 ° C. or less. The lower limit of the holding temperature is not particularly limited, but is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and still more preferably −25 ° C. or higher. When the holding temperature is in the above range, sterilization can be performed at a temperature at which general freezing storage or freezing transportation is performed.

The holding time of the holding step 12 is preferably within 100 hours. When the holding time is within 100 hours, the time required for the sterilization process can be made relatively short, so that the manufacturing process can be shortened. The holding time is more preferably 70 hours or less, further preferably 48 hours or less.
The holding time is preferably 70 hours or more. When the holding time is 70 hours or more, a sufficient bactericidal effect can be obtained. The holding time is more preferably 80 hours or more.

Here, in the method of sterilizing food according to the first embodiment, the principle of effective sterilization will be described. In the following description, the case where the content of ethanol 2 in the mixture 3 is 8% by weight will be described as an example.

Aqueous ethanol solutions have different freezing points depending on their mixing ratio. The mixture 3 in this embodiment contains 8% by weight of ethanol 2, and its freezing point is approximately -10 ° C. At this time, when the mixture 3 is held under the environment of holding temperature -20 ° C. (holding step 12), as the temperature of the mixture 3 decreases, a solid phase in which only water is precipitated and a liquid phase which is a mixture To separate. Since only water precipitates on the solid phase and ethanol 2 does not precipitate and remains in the liquid phase, the ethanol content in the liquid phase increases. Finally, the ethanol content of the liquid phase reaches 16% by weight, which is the ethanol content with a freezing point of −20 ° C. (ie consistent with the holding temperature).

Thus, holding the mixture containing ethanol at a holding temperature below the freezing point determined by its ethanol content will increase the ethanol content of the liquid phase. That is, ethanol is concentrated by freezing.

At this time, in the process of water precipitation, the microorganisms contained in the mixture 3 are extracted in the liquid phase. Therefore, concentrated ethanol 2 and microorganisms are present in the liquid phase, and the microorganisms are sterilized by the bactericidal effect of ethanol 2. By the way, the sterilizing effect by ethanol 2 becomes high, so that the ethanol content rate is high. Thus, the bactericidal effect in the liquid phase (ethanol content 16% by weight) kept at -20 ° C. is higher than the bactericidal effect in mixture 3 (ethanol content 8% by weight) before the holding step 12. In other words, it can be said that a higher bactericidal effect than expected from the amount of ethanol 2 originally contained in the mixture 3 is obtained by freezing.

The microorganisms targeted for sterilization in the method of sterilizing food according to the present embodiment are not particularly limited, but may be known microorganisms such as yeast, E. coli, staphylococcal bacteria, and lactic acid bacteria.

Other Embodiments
Next, another embodiment of the method of sterilizing food according to the present invention will be described. The configurations disclosed in each of the following embodiments can be applied in combination with the configurations disclosed in the other embodiments as long as no contradiction arises.

In the above embodiment, the case where the food to be sterilized is fruit juice 1 has been described as an example. However, the food to be sterilized is not limited to fruit juice, and may be, for example, fruits, vegetables, meats, fish and shellfish. At this time, the aspect of the fruit is not particularly limited, and the whole of the fruit, the peel of the fruit, the fruit of the fruit, the one obtained by cutting the fruit, the one obtained by crushing the fruit, or a mixture of two or more selected from these It may be. A known method can be used as a method of grinding the fruit, but freeze grinding is preferable.

In the above embodiment, the food to be sterilized is fruit juice 1, ie, the case where the food contains citric acid and sucrose has been described as an example. However, the food to be sterilized may not contain at least one of the organic acid and the sugar. Regardless of whether the food contains an organic acid and a sugar, the food may be mixed with the organic acid and the sugar in the mixing step such that the content of the organic acid and the sugar in the mixture falls within a preferred range.

In the above embodiment, the case where the mixture 3 contains fruit juice 1 and ethanol 2 and the fruit juice 1 contains citric acid and sucrose has been described as an example. However, the organic acid is not limited to citric acid, and may be an organic acid selected from the group consisting of citric acid, malic acid, tartaric acid and benzoic acid, and may be a mixture of a plurality of organic acids. The sugar is not limited to sucrose, and may be a sugar selected from the group consisting of sucrose, fructose, invert sugar and glucose, or may be a mixture of a plurality of sugars. The mixture may or may not further contain other optional components, such as preservatives, antioxidants, pH adjusters. In addition, water may be added to each of the components described above to adjust the concentration of the components in the mixture.

In the above embodiment, the case where the mixture 3 is obtained by the mixing step 11 which is a known mixing method has been described as an example. However, the mixture does not necessarily have to be obtained by the mixing process. For example, brewing a mixture containing sugar may be used as a mixture as it results in a brewed product in which a portion of the sugar is converted to ethanol.

With regard to the other configurations, it is to be understood that the embodiments disclosed herein are illustrative in all respects, and the scope of the present invention is not limited by them. Those skilled in the art will easily understand that appropriate modifications can be made without departing from the spirit of the present invention. Therefore, other embodiments modified within the scope of the present invention are naturally included in the scope of the present invention.

EXAMPLES The present invention will be described by way of examples, but the present invention is not limited to the following examples.

[Test bacteria]
Lactic acid bacteria were used as test bacteria in the tests shown in the following examples.

〔reagent〕
The following reagents were used in the tests shown in the following examples.
Ethanol: Nacalai Tesque, Inc., Grade EP, Purity 99.5
Citric acid: Nacalai Tesque, Inc., grade EP, purity 9 99.0
Sucrose: Nacalai Tesque, grade EP

[Fruit juice]
Commercially available grapefruit and lemon were respectively directly squeezed (super hand juicer TW-001) to obtain grapefruit juice of pH 3.3 and lemon juice of pH 2.3.

[Inoculation step]
10 mL of the sample solution was collected, and lactic acid bacteria were added and uniformly mixed to obtain an inoculum.

[Holding process]
The inoculum was kept in the freezer storage facility in which the temperature inside the freezer was kept at -20. +-. 4.degree. During the holding step, a measurement sample for viable cell count analysis was collected. At this time, the elapsed time from the start of holding to sampling was recorded as the holding time.

Viable count analysis
10 mL of a measurement sample was collected and diluted with sterile water to obtain a diluted sample. The diluted sample was solidified using a sterile pipette and evenly spread on a surface-dried agar medium with a Conlage bar. This was cultured for 96 hours in an incubator maintained at 35 ° C.
For the culture medium, the number of colonies formed was measured, and the obtained measurement value was multiplied by the dilution factor at the time of sample preparation to calculate the number N of bacteria per 1 g of the measurement sample. Assuming that the number of bacteria per 1 g of a sample measured by the same method for the sample before the sterilization step is N ₀ , the logarithmic reduction value LRV (D) of the number of bacteria after the sterilization step was calculated according to the following formula (I).
LRV (D) = Log ₁₀ (N ₀ / N) (I)

Example 1
0.1 g of citric acid, 1.0 g of sucrose and 0.8 g of ethanol are added to and mixed with 8.1 g of sterile water, and mixed, 1 wt% of citric acid, 10 wt% of sucrose and 8 wt% of ethanol To obtain a mixture containing. At this time, the pH of the mixture was 2.3. The said inoculation step and the said holding process were implemented in order with respect to the said mixture. For each measurement sample having different retention times, viable count analysis was performed according to the method described above to obtain LRV (D) values at each retention time. The retention times and LRV (D) values of the collected measurement samples are shown in Table 1.

Example 2
9.2 g of lemon juice and 0.8 g of ethanol were uniformly mixed to obtain a mixture containing 92% by weight of lemon juice and 8% by weight of ethanol. At this time, the pH of the mixture was 2.3. The said inoculation step and the said holding process were implemented in order with respect to the said mixture. For each measurement sample having different retention times, viable count analysis was performed according to the method described above to obtain LRV (D) values at each retention time. The retention times and LRV (D) values of the collected measurement samples are shown in Table 1.

[Example 3]
9.2 g of grapefruit juice and 0.8 g of ethanol were uniformly mixed to obtain a mixture containing 92 wt% of grapefruit juice and 8 wt% of ethanol. At this time, the pH of the mixture was 3.3. The said inoculation step and the said holding process were implemented in order with respect to the said mixture. For each measurement sample having different retention times, viable count analysis was performed according to the method described above to obtain LRV (D) values at each retention time. The retention times and LRV (D) values of the collected measurement samples are shown in Table 1.

Comparative Example 1
0.1 g of citric acid and 1.0 g of sucrose were added to 8.9 g of sterile water and mixed to obtain a mixture containing 1% by weight of citric acid and 10% by weight of sucrose. At this time, the pH of the mixture was 2.3. The said inoculation step and the said holding process were implemented in order with respect to the said mixture. For each measurement sample having different retention times, viable count analysis was performed according to the method described above to obtain LRV (D) values at each retention time. The retention times and LRV (D) values of the collected measurement samples are shown in Table 1.

Comparative Example 2
In the same manner as in Example 1 except that the temperature in the holding step was changed to 4 ± 1 ° C., LRV (D) values at each holding time were obtained. The retention times and LRV (D) values of the collected measurement samples are shown in Table 1.

Comparative Example 3
0.1 g of citric acid and 0.8 g of ethanol were added to 9.1 g of sterile water and mixed to obtain a mixture containing 1% by weight of citric acid and 8% by weight of ethanol. At this time, the pH of the mixture was 2.3. The said inoculation step and the said holding process were implemented in order with respect to the said mixture.
For each measurement sample having different retention times, viable count analysis was performed according to the method described above to obtain LRV (D) values at each retention time. The retention times and LRV (D) values of the collected measurement samples are shown in Table 1.

Comparative Example 4
To 8.2 g of sterile water, 1.0 g of succinic acid and 0.8 g of ethanol were added and mixed to obtain a mixture containing 10 wt% of sucrose and 8 wt% of ethanol. At this time, the pH of the mixture was 6.9. The said inoculation step and the said holding process were implemented in order with respect to the said mixture. For each measurement sample having different retention times, viable count analysis was performed according to the method described above to obtain LRV (D) values at each retention time. The retention times and LRV (D) values of the collected measurement samples are shown in Table 1.

Comparative Example 5
To 9.2 g of sterile water, 0.8 g of ethanol was added and mixed to obtain a mixture containing 8 wt% of ethanol. At this time, the pH of the mixture was 6.9. The said inoculation step and the said holding process were implemented in order with respect to the said mixture. For each measurement sample having different retention times, viable count analysis was performed according to the method described above to obtain LRV (D) values at each retention time. The retention times and LRV (D) values of the collected measurement samples are shown in Table 1.

[Bactericidal effect against the test bacteria]
The LRV (D) values at each holding time of Examples 1 to 3 and Comparative Examples 1 to 5 are shown in Table 1. When a mixture containing ethanol is maintained at or below the freezing point (Examples 1 to 3), a bactericidal effect is higher than when ethanol is not used (Comparative Example 1) or at a temperature above the freezing point (Comparative Example 2) was gotten. In addition, when a mixture containing citric acid and sucrose is used (Example 1) or when juice containing citric acid and fructose is used (Examples 2 and 3), only citric acid is contained (Comparative Example) 3) A high bactericidal effect was shown as compared with the case where only sucrose was contained (comparative example 4) and the case where sterile water was used (comparative example 5).

The present invention can be used, for example, to sterilize juice used as a raw material of alcoholic beverages.

Claims (6)

Food, organic acid, sugar, and a mixture containing ethanol, or
A food containing an organic acid and a sugar, and a mixture containing ethanol,
Having a holding step of holding at -10 ° C. or less,
The ethanol content in the mixture is 0.08-8% by weight,
The method for sterilizing a food, wherein the food is at least one food selected from fruits, fruit juices, and vegetables. The method for sterilizing food according to claim 1, wherein the holding step is within 100 hours. The method according to claim 1 or 2, wherein the content of the organic acid in the mixture is 0.01 to 10% by weight. The method for sterilizing food according to any one of claims 1 to 3, wherein the organic acid is citric acid. The method according to any one of claims 1 to 4, wherein the content of sugar in the mixture is 1 to 10% by weight. The method according to any one of claims 1 to 5, wherein the sugar is at least one sugar selected from sucrose and fructose.

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