JP2020099291A - Sterilization method and sterilization apparatus of food product - Google Patents

Abstract

To propose an effective and efficient sterilization method capable of suppressing proliferation of viable bacteria and quality degradation of food products under low temperature without using a high concentration bactericide.SOLUTION: A sterilization method of food products includes a preliminary step for injecting fine bubbles into an aqueous solution containing a bactericide at 10°C or lower and a sterilization step for sterilizing food products using the aqueous solution containing the fine bubbles.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a food sterilizing method and a sterilizing apparatus.

As a trend of hygienic control in food manufacturing processes that do not heat sterilize, in order to prevent the occurrence of food poisoning due to pathogenic bacteria such as botulinum and salmonella, low temperature control of food and microbial control by thorough sterilization are being implemented. Chlorine-based bactericides typified by sodium hypochlorite are widely used in the sterilization process of unheated foods (for example, vegetables and fruits). As a method of using sodium hypochlorite, in fresh vegetables, a sodium hypochlorite aqueous solution having a predetermined concentration is prepared, and the food material to be immersed is immersed in the aqueous solution for a predetermined time, and then the live bacteria attached to the food are treated. The food is sterilized by the oxidizing action of sodium chlorite.
However, a chlorine-based bactericide represented by sodium hypochlorite has a bactericidal action due to an oxidation reaction, and therefore, the bactericidal ability (bactericidal rate, bactericidal rate) is significantly weakened due to the stagnation of the oxidation reaction in low-temperature cooling water. It is said.

In Non-Patent Document 1, the rate of cleaning (removal of stains) and sterilization (killing of bacteria) due to the oxidizing action of sodium hypochlorite increases with an increase in temperature, and is calculated from the Arrhenius equation. It is described that the temperature dependence of Arrhenius type is shown.
Patent Documents 1 to 4 disclose that fine bubbles are mixed into an aqueous solution containing hypochlorous acid to enhance the sterilizing effect of food. In these patent documents, using carbon dioxide gas as fine bubbles, enhance the sterilizing effect by slightly acidifying the aqueous solution, or by bringing the sterilizing effect into contact with the base skin of the food by the stirring effect by the rupture of fine bubbles, the sterilizing effect is obtained. It is stated that it can be increased. The sterilization process is performed at room temperature in all cases, and further, low temperature storage is performed in the process of observing the progress after the sterilization process. It is considered that this is because the temperature dependence in which the sterilization rate decreases as the temperature decreases is taken into consideration.

International Publication No. 2015/071995 International Publication No. 2013/125051 JP, 2013-240742, A JP, 2009-268394, A

Satoshi Fukusaki, Hiromizu Urano, Kazuhiro Takahashi, Sadako Yamada, Akihiko Takagi (Okayama Prefectural University) "Effect of temperature on cleaning and sterilizing effect of sodium hypochlorite" (Okayama Industrial Technology Center 2010 Center Report ( No. 37)))

Usually, the washing and sterilization of foods are carried out by immersing them in low-temperature cooling water in order to prevent the growth of microorganisms and to prevent the deterioration of food quality. However, as described above, since it is said that the bactericidal ability of the bactericide decreases in low-temperature cooling water, it is considered necessary to use a high-concentration bactericide. However, use of a high-concentration bactericide causes problems such as influence of odor on food quality, deterioration of working environment, and generation of trihalomethane. Therefore, there is a demand for a technique capable of sterilizing effectively and efficiently at low temperature without using a high concentration bactericide.

One embodiment is to propose a sterilization method for effectively and efficiently performing sterilization of food at a low temperature capable of suppressing the growth of live bacteria and quality deterioration of food without using a high concentration bactericide. And

(1) The method of sterilizing food according to one embodiment is
A preliminary step of mixing fine air bubbles in an aqueous solution containing a bactericide at 10°C or lower,
A sterilization step of sterilizing food using the aqueous solution containing the fine bubbles,
including.

The factors that control the bactericidal reaction of viable bacteria are the temperature and the concentration of the bactericide. When a material causes a chemical reaction such as oxidation in a microorganism, the Arrhenius equation for predicting the rate of the chemical reaction has been proposed. According to the Arrhenius equation, only a molecule having an energy (kinetic energy) equal to or higher than the activation energy before the reaction is interpreted as proceeding the reaction across the energy barrier. According to this interpretation, the reaction rate is increased when the temperature is high and the activation energy is low.
As described above, conventionally, sterilization using a disinfectant such as sodium hypochlorite shows Arrhenius-type temperature dependence obtained from the Arrhenius equation, and the sterilization rate is large and the action is high in the normal temperature range, It is said that the sterilization rate becomes low and the sterilization effect is greatly reduced in the low temperature range. Therefore, until now, in the steps before and after the sterilization process, in order to suppress the growth of microorganisms and the deterioration of the quality of foods, cleaning is performed using low-temperature cooling water, but the sterilization process is performed at room temperature, and therefore, in the low temperature range. No experimental data for sterilization is given.

On the other hand, the present inventors have experimentally found that when fine air bubbles are mixed in an aqueous solution containing a bactericide at 10° C. or less, the bactericidal reaction proceeds without being weakened. As a result, it is possible to effectively and efficiently perform the sterilization treatment in a low temperature range that is favorable for hygiene control and food quality without using a high concentration bactericide. Therefore, while suppressing the growth of viable bacteria and suppressing the deterioration of the quality of foods and the like, it is possible to solve the problems such as the generation of trihalomethane and further contribute to the improvement of the working environment.

(2) In one embodiment, in the configuration of (1) above,
In the preliminary step, fine bubbles are mixed into the aqueous solution to increase the sterilization rate constant and decrease the activation energy.
The present inventors, by mixing fine air bubbles in an aqueous solution containing a bactericide at 10° C. or less, increase the sterilization rate constant used in the below-described Chick-Watson equation even under conditions where the temperature of the aqueous solution is low. It was found experimentally that the energy of oxidization is reduced. As a result, it is possible to promote the oxidative reaction with respect to viable bacteria by overcoming the energy barrier with low energy in a low temperature range, and to improve the efficiency of the sterilization process of food.

(3) In one embodiment, in the method of (1) or (2) above,
In the sterilization step, the food is immersed in the aqueous solution stored in the water tank.
According to the method of (3) above, by immersing the food in the aqueous solution stored in the water tank, the oxidative action on the viable bacteria adhering to the food over the entire surface area of the food occurs, so that the sterilization rate can be increased. ..

(4) In one embodiment, in the configuration according to any one of (1) to (3) above,
The bactericide contains a substance having an oxidative effect on living bacteria adhering to the food.
According to the above method (4), since the bactericide contains a substance having an oxidizing effect on live bacteria, it can oxidize and kill essential tissues such as cell walls, plasma membranes and nucleic acids of live bacteria attached to food.

(5) In one embodiment, in the method of (4) above,
The bactericide contains a substance capable of producing hypochlorous acid in the aqueous solution.
According to the above method (5), the bactericidal agent can generate hypochlorous acid which has a strong oxidizing action on living bacteria in the aqueous solution, so that the bactericidal effect can be improved and the sterilizing step can be made efficient.

(6) In one embodiment, in the method according to any one of (1) to (5) above,
The fine bubbles are formed to have a diameter of 100 μm or less.
According to the above method (6), since the fine bubbles have a diameter of 100 μm or less, the ratio of the surface area to the volume (specific surface area) can be increased. Thereby, the fine bubbles can be uniformly dispersed in the aqueous solution for a long period of time. In addition, since fine bubbles having a diameter of 100 μm or less have a negative (−) chargeability on the surface, they can exist in an aqueous solution in a densely aggregated state. These properties are believed to contribute to the reduction of activation energy.

(7) In one embodiment, in the method according to any one of (1) to (6) above,
The fine bubbles are formed by using an inert gas.
According to the above method (7), since the fine bubbles are formed of the inert gas, the reaction with the aqueous solution is suppressed, and the fine bubbles can exist for a long time in the aqueous solution.

(8) In one embodiment, in any one of the methods (1) to (6) above,
The fine bubbles are formed by using a gas capable of oxidizing live bacteria adhering to the food.
According to the method of (8) above, since the fine bubbles are formed by using a gas capable of oxidizing the viable bacteria adhering to the food, in addition to the bactericidal effect of the bactericidal agent, A bactericidal effect can be exhibited, which synergistically enhances the bactericidal effect and makes the sterilization process efficient.

(9) The food sterilizer according to one embodiment is
A container for storing an aqueous solution containing a bactericide,
A temperature control unit that holds the aqueous solution stored in the container at a temperature of 10° C. or lower;
A bactericide concentration adjusting unit for adjusting the concentration of the bactericide in the aqueous solution,
A fine bubble generating section for mixing fine bubbles into the aqueous solution,
Equipped with.
According to the configuration of (9), the food is sterilized with an aqueous solution containing a bactericidal agent and containing fine bubbles at a temperature of 10° C. or lower, which is necessary to cause an oxidative reaction by the bactericidal agent with respect to live bacteria adhering to the food. The activation energy can be reduced. As a result, the sterilization speed can be increased, and the sterilization process can be effective and efficient. Further, for the aqueous solution in the container into which the sterilizing agent is charged, since the fine bubble generating section is provided independently of the sterilizing agent concentration adjusting section, the fine bubble generating step is independent of adjusting the sterilizing agent concentration of the aqueous solution. Can be adjusted. This facilitates the adjustment of the bactericide concentration and the amount of fine air bubbles mixed.

(10) In one embodiment, in the configuration of (9) above,
A nozzle for spraying the aqueous solution stored in the container onto food is provided.
According to the configuration of (10), the food can be sterilized by spraying the aqueous solution containing the fine bubbles and the germicide from the nozzle. As a result, the sterilization of the food immersed in the aqueous solution in the container and the sterilization of the food by the nozzle can be performed simultaneously and separately, and the sterilization process can be made more efficient.

(11) In one embodiment, in the configuration of (9) or (10) above,
The temperature control unit,
A refrigerant generation unit,
A refrigerant circulation path introduced from the refrigerant generation unit into the aqueous solution,
Equipped with
The coolant generated by the coolant generation unit is circulated in the coolant circulation path to exchange heat between the aqueous solution and the coolant.
According to the configuration of (11) above, the temperature control unit having the above configuration can adjust the temperature of the aqueous solution containing the bactericide and the fine bubbles to 10° C. or lower.

According to some embodiments, by sterilizing a food with an aqueous solution containing a bactericide and containing fine bubbles and having a temperature of 10° C. or less, the sterilization speed of the food can be increased and the sterilization process can be made efficient. By this, while suppressing the growth of viable bacteria in the low temperature range, and suppressing the deterioration of food quality, etc., effective and efficient sterilization can be performed without using a high concentration bactericide, and problems such as the generation of trihalomethanes occur. It can be solved and contribute to the improvement of the work environment.

It is process drawing of the sterilization method of the foodstuff which concerns on one Embodiment. It is explanatory drawing explaining the fall of the activation energy in a sterilization reaction. It is a graph which shows the temperature dependence of the bactericidal ability by a bactericide. It is a graph which shows the temperature dependence of the bactericidal ability by a bactericide with a bactericidal rate constant. It is a graph which shows transition of the sterilization rate when there is no fine air bubble. It is a graph which shows the transition of the sterilization rate when there are fine bubbles. It is a graph which shows the transition of the sterilization rate when the temperature of the aqueous solution is 25°C. It is a graph which shows transition of the sterilization rate when the temperature of the aqueous solution is 5°C. It is a graph which shows a sterilization rate constant when the temperature of an aqueous solution is 25°C. It is a graph which shows the sterilization rate constant when the temperature of aqueous solution is 5 degreeC. It is a graph which shows the activation energy concerning one Embodiment. It is a block diagram of the sterilizer of the foodstuff which concerns on one Embodiment.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples.
For example, the expression "relative or absolute" such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" is strict. In addition to representing such an arrangement, it also represents a state of relative displacement or a relative displacement with an angle or distance to the extent that the same function can be obtained.
For example, expressions such as "identical", "equal", and "homogeneous" that indicate that they are in the same state are not limited to strict equality, but also include tolerances or differences in the degree to which the same function is obtained. It also represents the existing state.
For example, the representation of a shape such as a quadrangle or a cylinder does not only represent a shape such as a quadrangle or a cylinder in a geometrically strict sense, but also an uneven portion or a chamfer within a range in which the same effect can be obtained. The shape including parts and the like is also shown.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one element are not exclusive expressions excluding the existence of other elements.

FIG. 1 is a process diagram of a food sterilization method according to an embodiment. This sterilization method includes a preliminary step S10 and a sterilization step S12 as basic steps. In the preliminary step S10, fine bubbles are mixed into an aqueous solution containing a bactericide at 10° C. or lower. In the sterilization step S12, the food is sterilized using an aqueous solution containing fine bubbles.
The present inventors have experimentally found that when fine bubbles are mixed in an aqueous solution containing a bactericide at 10° C. or lower, the bactericidal reaction proceeds without being weakened. As a result, it is possible to effectively and efficiently carry out the sterilization treatment in a low temperature range which is favorable for hygiene control and food quality without using a high concentration bactericide. Therefore, problems such as generation of trihalomethane can be solved while suppressing the growth of viable bacteria and suppressing the deterioration of food quality.

In one embodiment, in the preliminary step S10, microbubbles are mixed into the aqueous solution containing the bactericide to increase the sterilization rate constant and decrease the activation energy.
The present inventors, by mixing fine air bubbles in an aqueous solution containing a bactericide at 10° C. or lower, increase the sterilization rate constant used in the below-described Check-Watson formula under conditions where the temperature of the aqueous solution is low, and It was found experimentally that the energy of oxidization is reduced. As a result, it is possible to proceed with the oxidation reaction to live bacteria by overcoming the energy barrier with low energy in a low temperature region, which makes the sterilization process of food more efficient and contributes to further improvement of the working environment.

In one embodiment, in the sterilization step S12, the food is immersed in the aqueous solution stored in the water tank. According to this embodiment, by immersing the food in the aqueous solution stored in the aquarium, the oxidative effect on the live bacteria adhered to the food over the entire surface area of the food occurs, so that the sterilization speed can be increased and the sterilization efficiency can be improved. ..

In one embodiment, as a bactericidal agent, a substance having an oxidative effect on living bacteria adhering to food is included. As a result, essential tissues such as cell walls of live bacteria, plasma membrane, and nucleic acids attached to food can be oxidized and killed. Examples of substances that can oxidize food include hydrogen peroxide (H ₂ O ₂ ), ozone water in which ozone is dissolved, electrolyzed water produced by electrolyzing salt water, hypochlorous acid (NaOCl), and the like. Examples include chlorate.

In one embodiment, the germicide comprises a substance capable of producing hypochlorous acid (HOCl) in aqueous solution. These substances can improve the bactericidal effect by generating hypochlorous acid having a strong oxidizing action in the aqueous solution, thereby making the sterilization process efficient. The substance capable of producing hypochlorous acid in an aqueous solution is, for example, a hypochlorite salt represented by sodium hypochlorite.

As shown in FIG. 2, in the Arrhenius equation, the progress of the sterilization reaction (oxidation reaction) is as follows: (1) contact between live bacteria b and bactericide h adhering to food, (2) live bacteria b and bactericide h It is construed that the oxidation reaction between them crosses the peak of the activation energy Ea, leading to (3) sterilization of the live bacteria b. The activation energy Ea is also given from the ambient temperature. Therefore, the progress of the bactericidal reaction is limited by the size of the chance of contact of the bactericide h with the live bacterium b, that is, the concentration of the bactericide h and the environmental temperature.
The present inventors have found that the activation energy Ea can be reduced (Ea→Ea′) by including fine bubbles in the aqueous solution containing the bactericide h when the aqueous solution to which the bactericide is added is 10° C. or lower. Found experimentally. The process leading to this finding will be described below.

FIG. 3 shows the results of observing the transition of the sterilization rate by filling the water tank with an aqueous solution containing viable bacteria, adding 14 mg/L of sodium hypochlorite to the aqueous solution, and changing the water temperature variously. On the vertical axis, a sterilization rate of 0.2 indicates that live cells could be sterilized by 20%, and a sterilization rate of 1.0 indicates that live cells could be sterilized by 100%. It can be seen from FIG. 3 that the lower the temperature of the aqueous solution is, the lower the sterilization rate is, and that the sterilization rate greatly changes at the temperature of the aqueous solution near 10° C. of the aqueous solution.

As described in Non-Patent Document 1, the following Chick-Watson equation is used for the analysis of the sterilization curve showing the change in the viable cell count due to the bactericidal action of the bactericide.
log(N/N ₀ )=−kCT (1)
Here, N ₀ : initial number of bacteria, N: number of viable bacteria, C: concentration of bactericide, T: sterilization time, k: sterilization rate constant (l (liter)/mmol·min).
FIG. 4 is a graph in which the experimental results shown in FIG. 3 are applied to the equation (1). The numerical value of each line in the figure represents the sterilization rate constant k. It can also be seen from FIG. 4 that the lower the temperature of the aqueous solution, the smaller the sterilization rate constant k, and that the sterilization rate constant k greatly changes with the temperature of the aqueous solution near 10° C. as the boundary.

5A and 5B are graphs showing transitions of the sterilization rate when the water tank is filled with an aqueous solution containing viable bacteria, the temperature of the aqueous solution is 5° C., and the concentration of sodium hypochlorite is variously changed. FIG. 5A shows a case where fine bubbles are not mixed in the aqueous solution, and FIG. 5B shows a case where fine bubbles having a diameter of 100 μm or less are mixed. In FIG. 5A, even if the concentration of the bactericide is changed from 14 mg/L to 140 mg/L which is 10 times the concentration, the bactericidal rate remains at 0.5 and does not change much. On the other hand, when there are fine bubbles in FIG. 5B, the sterilization rate was 1.0 at 70 mg/L or 140 mg/L after 20 minutes, and the sterilization rate of 0.8 was obtained even at 14 mg/L. From these figures, it is understood that the sterilization rate is greatly improved by mixing fine bubbles. In addition, the sterilization rate does not change much depending on the concentration of sodium hypochlorite when there are no fine bubbles, whereas when the fine bubbles are mixed, the sterilization rate is improved compared to when the fine bubbles are not mixed. Moreover, it can be seen that the sterilization rate changes depending on the concentration of sodium hypochlorite. That is, the higher the concentration, the higher the sterilization rate. The following can be inferred from the results of this experiment. That is, as shown in FIG. 5A, when fine air bubbles are not mixed, the activation energy Ea is not exceeded in any case regardless of the concentration of sodium hypochlorite, so that the sterilization rate is not improved even if the concentration is changed. Also, the difference in sterilization rate due to the difference in concentration does not appear clearly. As shown in FIG. 5B, when fine bubbles are mixed, the activation energy Ea is exceeded regardless of the concentration of sodium hypochlorite, so that the sterilization rate is improved and the sterilization rate due to the difference in concentration is increased. The difference between From the above consideration, it can be seen that the activation energy Ea is lower when the fine bubbles are mixed in than when the fine bubbles are not mixed.

Next, the water tank was filled with an aqueous solution having a sodium hypochlorite concentration of 100 mg/L, and the bean sprouts sample was immersed in this aqueous solution as food, with and without fine air bubbles having a diameter of 100 μm or less. The transition of the sterilization rate of live bacteria adhering to the sample was observed. 6A and 6B show these results. In FIG. 6A, the temperature of the aqueous solution is kept at 25° C., and in FIG. 6B, the temperature of the aqueous solution is kept at 5° C. As shown in FIG. 6A, when the temperature of the aqueous solution was 25° C., almost the same high sterilization rate was exhibited regardless of the presence or absence of fine bubbles. It is considered that this is because the temperature of the aqueous solution is high, so that the energy of the aqueous solution causes an oxidation reaction in which both have a potential exceeding the activation energy Ea. In this state, the ability of the bactericidal agent is fully exerted, and both have high sterilization rates, so it is considered that there may be a significant difference in the bactericidal effect depending on the presence or absence of fine bubbles.

On the other hand, as shown in FIG. 6B, when the temperature of the aqueous solution is 5° C., a large difference can be seen in the sterilizing effect between the two in the first half stage of the sterilizing process. The reason for this is that the activation energy Ea decreases when fine bubbles are mixed in, and the oxidation reaction begins early beyond the activation energy Ea, whereas the activation energy Ea does not occur when fine bubbles are not added. It is considered that the oxidation reaction did not start because the reduction of Ea did not occur. Therefore, as shown in FIG. 6B, it is understood that by adding fine bubbles, the sterilization rate constant k can be increased and the activation energy Ea decreases, so that the sterilization efficiency can be improved.

Using the value of the sterilization rate constant k obtained by the equation (1) and rearranging according to the Arrhenius equation, the following equation (2) is established.
In(k)=-Ea/RT+In(A) (2)
Here, Ea; activation energy Ea; activation energy (J/mol), R; gas constant (8.314/K·mol), T; sterilization temperature (K), A; frequency factor (l (liter)) /Mmol·min).
Further, in Non-Patent Document 1, it is described that "there is a linear relationship between In(k) and 103/T, and Ea is calculated from this inclination." Can be converted into the equation (2)'.
In(k)=(−Ea/10 ³ R)·(10 ³ /T)+In(A) (2)′

In the graph of the vertical axis In(k) and the horizontal axis 10 ³ /T in FIG. 8, In(k)=−P·(10 ³ /T)+C is plotted and the obtained slope is “−P”,
-P=-Ea/10 ³ R
Ea=10 ³ R·P (J/mol)
= RP (kJ/mol)
= 8.314P (kJ/mol)
From the above, the activation energy Ea (J/mol) can be obtained from the slope of the straight line plotted in the graph of FIG.

7A and 7B show the process of calculating the activation energy Ea by the equation (2) with respect to the experimental results shown in FIGS. 6A and 6B. The numerical value in the figure shows the sterilization rate constant k. As shown in FIG. 7A, when the temperature of the aqueous solution is 25° C., the value of the sterilization rate constant k increases regardless of the presence or absence of fine bubbles, and there is almost no difference between the two. On the other hand, as shown in FIG. 7B, when the temperature of the aqueous solution is 5° C., there is a large difference in the value of the sterilization rate constant k depending on the presence or absence of fine bubbles, and the value of the sterilization rate constant k with fine bubbles is large. More than. This is because when the fine bubbles are added, the activation energy Ea is reduced, and the oxidation reaction occurs while overcoming the activation energy Ea, whereas when the fine bubbles are not added, the activation energy Ea is increased. It is considered that this is because the activation energy Ea cannot be overcome and the oxidation reaction has not occurred because the amount of oxygen does not decrease.

FIG. 8 shows the result of calculating the activation energy Ea based on the experimental result shown in FIG. 7B. Ea=35.8 (kJ/mol) when there are no fine bubbles, and Ea=2.7 (kJ/mol) when there are fine bubbles. As shown in FIG. 8, when the fine bubbles are added, the activation energy Ea is significantly reduced as compared with the case where the fine bubbles are not added.

In one embodiment, the microbubbles are formed to have a diameter of 100 μm or less in an aqueous solution. According to this embodiment, since the fine bubbles have a diameter of 100 μm or less, the ratio of the surface area to the volume (specific surface area) can be increased. Thereby, it can be uniformly dispersed in the aqueous solution for a long period of time. In addition, since fine bubbles having a diameter of 100 μm or less have a negative (−) chargeability on the surface, they can exist in an aqueous solution in a densely aggregated state. These properties are believed to contribute to the reduction of activation energy.

Micro bubbles having a diameter of 100 μm or less are classified into those having a diameter of 1 to 100 μm and those having a diameter of 1 μm or less, and both have different characteristics. The former is cloudy and visible in an aqueous solution, while the latter is colorless and transparent in an aqueous solution and invisible. In addition, the former is known to dissolve and disappear in an aqueous solution due to the self-pressurization effect, and it has been suggested by numerical simulation that local high temperature and high pressure occur in the process. It is speculated that this effect promotes sterilization by the oxidation reaction even at low temperatures. The latter can maintain a long dispersion time in an aqueous solution.

In one embodiment, the microbubbles are formed with an inert gas. Since the fine bubbles are formed of the inert gas, the reaction with the aqueous solution is suppressed, and the fine bubbles can stay in the aqueous solution for a long time. As the inert gas, for example, nitrogen gas, argon gas or the like can be used.

In one embodiment, the microbubbles are formed using a gas capable of oxidizing food. Since the fine bubbles are formed by using a gas that can oxidize food, in addition to the sterilizing effect of the bactericide, the bactericidal effect of live bacteria due to the oxidizing action of the fine bubbles can be exhibited. This synergistically enhances the sterilization effect and makes the sterilization process efficient. As the oxidizable gas, for example, ozone gas can be used.

As shown in FIG. 9, a food sterilization apparatus 10 according to an embodiment has a container 12 for storing an aqueous solution containing a bactericide, and a temperature for holding the aqueous solution stored in the container 12 at a temperature of 10° C. or lower. An adjusting unit 14, a sterilizing agent concentration adjusting unit 15 for adjusting the concentration of the sterilizing agent in the aqueous solution, and a fine bubble generating unit 16 for mixing fine bubbles g into the aqueous solution are provided. A bactericide such as sodium hypochlorite is added to the aqueous solution stored in the container 12, and fine bubbles are sent from the fine bubble generating unit 16. The food f to be sterilized is added to this aqueous solution to oxidize live bacteria adhering to the food f for sterilization. The disinfectant concentration adjusting unit 15 may be configured to monitor the concentration of the disinfectant in the aqueous solution and add the disinfectant so as to maintain the required concentration.

According to the above configuration, by sterilizing the food with an aqueous solution containing a bactericide and containing fine bubbles g at 10° C. or less, the activation energy required for the oxidation reaction by the bactericide can be reduced, thereby increasing the sterilization rate. It can be accelerated and the sterilization process can be made efficient. Further, since the fine bubble generating section 16 is provided separately from the bactericide concentration adjusting section 15 for the aqueous solution in the container 12 into which the bactericide is put, it is independent of the adjustment of the bactericide concentration of the aqueous solution. Therefore, the amount of fine bubbles mixed can be adjusted. This facilitates the adjustment of the bactericide concentration and the amount of fine air bubbles mixed.

In one embodiment, the nozzle 18 that sprays the aqueous solution containing the fine bubbles g stored in the container 12 onto the food f is provided. According to this embodiment, the aqueous solution containing the fine bubbles g and the sterilizing agent in the container 12 is sent to the nozzle 18 through the conduit 20, and the aqueous solution can be sprayed from the nozzle 18 onto the food f to sterilize the food. By combining the sterilization by the nozzle 18 and the sterilization of the food f immersed in the aqueous solution in the container 12, the sterilization process of the food f can be made more efficient.

In one embodiment, the temperature control unit 14 includes a refrigerant generation unit 22 and a refrigerant circulation path 24 that is introduced from the refrigerant generation unit 22 into the aqueous solution in the container 12. The cooled coolant is generated in the coolant generation unit 22, and the coolant is circulated in the coolant circulation path 24. The coolant flowing through the coolant circulation path 24 cools the aqueous solution in the container 12.
According to this embodiment, the aqueous solution containing the bactericide stored in the container 12 can be adjusted to a temperature of 10° C. or lower by the temperature adjusting unit 14 having the above configuration.

In one embodiment, the pipe line 26 and the pipe line 28 are connected between the container 12 and the fine bubble generation part 16. The water containing fine bubbles is supplied from the fine bubble generating unit 16 to the container 12 via the pipe line 26. The aqueous solution in which the content of the fine bubbles in the container 12 is reduced is sent to the fine bubble generating unit 16 via the pipe line 28, mixed with the fine bubble in the fine bubble generating unit 16, and then passed through the pipe line 26. It is returned to the container 12. The fine bubble generator 16 is provided with an air intake tube 30 for taking in air for forming fine bubbles.

In one embodiment, the sterilizer 10 is operated in the following procedure.
(1) The fine bubbles are introduced from the fine bubble generating unit 16 into the aqueous solution stored inside the container 12.
(2) The coolant is circulated from the temperature controller 14 to the coolant circulation path 24 to regulate the aqueous solution in the container 12 to a low temperature of 10° C. or lower.
(3) A bactericide, for example, sodium hypochlorite is added to the aqueous solution to adjust the sodium hypochlorite in the aqueous solution to a predetermined concentration.
(4) Sterilize by immersing the food to be sterilized in the aqueous solution.
According to this embodiment, the temperature control unit 14 can control the temperature of the aqueous solution containing the bactericide and fine bubbles to 10° C. or lower.

In one embodiment, in place of the batch type sterilizer, a conveyor that conveys food to be sterilized, and a water tank that stores an aqueous solution containing a sterilizing agent and fine bubbles, and convey the food on the conveyor. However, it may be a continuous treatment type sterilizer that is immersed in an aqueous solution stored in a water tank and sterilized.

According to some embodiments, it is possible to effectively and efficiently perform the sterilization treatment of food at a low temperature that can suppress the growth of viable bacteria and can suppress the deterioration of the quality of food.

10 Sterilizer 12 Container 14 Temperature Control Section 15 Sterilizer Concentration Control Section 16 Micro Bubble Generation Section 18 Nozzles 20, 26, 28 Pipeline 22 Refrigerant Generation Section 24 Refrigerant Circulation Channel 30 Air Intake Pipe

Claims (11)

A preliminary step of mixing fine air bubbles in an aqueous solution containing a bactericide at 10°C or lower,
A sterilization step of sterilizing food using the aqueous solution containing the fine bubbles,
A method for sterilizing foods, which comprises: The method for sterilizing food according to claim 1, wherein in the preliminary step, sterilization rate constant is increased and activation energy is decreased by mixing fine bubbles into the aqueous solution. The sterilization method of food according to claim 1 or 2, wherein in the sterilization step, the food is immersed in the aqueous solution stored in a water tank. The said disinfectant contains the substance which can oxidize the live bacteria adhering to the said foodstuff, The sterilization method of the foodstuff in any one of Claim 1 thru|or 3 characterized by the above-mentioned. The sterilizing method of food according to claim 4, wherein the sterilizing agent contains a substance capable of generating hypochlorous acid in the aqueous solution. The method for sterilizing food according to claim 1, wherein the fine bubbles are formed to have a diameter of 100 μm or less. 7. The method for sterilizing food according to claim 1, wherein the fine bubbles are formed by using an inert gas. The said micro air bubble is formed using the gas which can oxidize the live bacteria adhering to the said foodstuff, The sterilization method of the foodstuff in any one of the Claims 1 thru|or 6 characterized by the above-mentioned. A container for storing an aqueous solution containing a bactericide,
A temperature control unit that holds the aqueous solution stored in the container at a temperature of 10° C. or lower;
A bactericide concentration adjusting unit for adjusting the concentration of the bactericide in the aqueous solution,
A fine bubble generating section for mixing fine bubbles into the aqueous solution,
An apparatus for sterilizing food, comprising: The sterilizer for food according to claim 9, further comprising a nozzle that sprays the aqueous solution stored in the container onto the food. The temperature control unit,
A refrigerant generation unit,
A refrigerant circulation path introduced from the refrigerant generation unit into the aqueous solution,
Equipped with
The sterilizer for food according to claim 9 or 10, wherein the refrigerant generated by the refrigerant generator is circulated in the refrigerant circulation path to exchange heat between the aqueous solution and the refrigerant. ..

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