JPH09266781A - Sterilization of food - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sterilize a food or a food material contaminated with spore-forming bacteria without deteriorating taste and palatability by bring the food or the food material into contact with a solid-free solution separated from a cultured product of mold fungi, yeast, bacteria or actinomyces and subsequently heating at a specific temperature. SOLUTION: A food or a food material contaminated with spore-forming bacteria (e.g. Bacillus coagulans JCM 2257) is brought into contact with a solid- free solution separated from a cultured product of mold fungi [e.g. Gymnoascus reessii AJ-7589 (FERM P-15443)], yeast (e.g. Saccharomyces uvarum), bacteria (e.g. Pseudomonas pseudoalcaligenes) or actinomyces (e.g. Promicromonospora sp.), and subsequently heated at a temperature between <=100 deg.C and >=21 deg.C. Thus, the objective food is efficiently sterilized without deteriorating taste and palatability.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for sterilizing foods, and more specifically, it is difficult to complete sterilization by heat treatment in a much lower temperature range as compared with conventional methods for sterilizing foods. The present invention relates to a method for sterilizing all microorganisms including a conventional spore-forming microorganism (hereinafter referred to as spore-forming bacterium).

[0002]

2. Description of the Related Art As a conventional heat sterilization method for foods, a method has been adopted in which foods or food materials are heated under pressure at a boiling point or higher.

Among the microorganisms that adhere to foods or food materials and are subjected to heat sterilization, there are spore bacteria that have strong resistance to heating.

If the spore-bacteria are heated and pressed by the conventional heat sterilization method until they can be completely sterilized, the taste and texture of the food are significantly deteriorated, and the nutritional components are destroyed. Furthermore, "browning" (browning) may occur, and the value as a food may be lost.

In order to avoid these problems, conventionally, for example, a method of allowing a reducing substance to coexist during retort packaging / heat sterilization, a relatively low temperature, for example, a method of intermittently heating at 100 ° C. a plurality of times, a relatively low temperature Under the circumstances, methods of applying ultrahigh pressure have been studied. Also, some of these methods are actually used.

However, even with the methods and sterilization methods actually used at present, it is a sufficiently effective method for sterilizing spore spores with high heat resistance while preserving the quality of foods. Is hard to say.

[0007]

The object of the present invention is to prevent all foods or food materials, including spore-forming bacteria, from adhering to foods or food materials even if the foods or food materials are heated in a low temperature range below the conventional common sense. The object is to provide an effective method for killing microorganisms.

[0008]

Means for Solving the Problems The inventors of the present invention have earnestly studied to solve the above problems, and have obtained the following new findings.

(A) An active factor that significantly reduces the heat resistance of spores is present in the non-solid section produced by a specific microorganism. (B) Even if the food or food material brought into contact with the non-solid section is heated at a relatively low temperature, at a temperature in the range of boiling point to room temperature or higher, all the substances attached to the food or food material, including spores and spore germs Being able to inactivate microorganisms. (C) Heating at a temperature in the range of not higher than boiling point and not lower than room temperature hardly causes a change in taste and texture of a food or food material as compared with heating at a temperature not lower than boiling point.

The present invention has been completed based on these findings, and in order to solve the above-mentioned problems, the method for sterilizing foods or food materials according to the invention of claim 1
A food or food material in which spore-forming microorganisms are present,
It is characterized in that it is heated to 100 ° C or lower and 21 ° C or higher after being brought into contact with a solid-free liquid separated from a culture of filamentous fungi, yeasts, bacteria or actinomycetes.

Further, the sterilization method of the food or food material according to the invention of claim 2 is characterized in that the filamentous fungus in the invention of claim 1 is a filamentous fungus belonging to the genus Gymnoascus. Is.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The microorganism producing a solid-free liquid separated from the culture used in the present invention is selected from filamentous fungi, yeasts, bacteria or actinomycetes. In particular, the filamentous fungus is a filamentous fungus belonging to the genus Gymnoascus, especially Gymnoascus lacy
oascus reessii) is selected.

As a representative strain thereof, Gymnoascus reessii AJ-7589 is selected. This strain has been deposited at the Institute of Biotechnology, Institute of Biotechnology, Ministry of International Trade and Industry on February 16, 1996, with the document indicating the taxonomic position attached, and the deposit number is FERM P- 1
It is 5443.

As the yeast, especially Saccharomyces (Sacc
Yeast belonging to the genus haromyces, especially Saccharomyces uvarum, is selected.

As bacteria, in particular Pseudomonas (Pseu)
bacteria belonging to the genus domonas, among others, Pseudomonas pseudoalcaligenes
Is selected.

As the actinomycetes, particularly actinomycetes belonging to the genus Promicromonospora, especially Promicromonospora sp.
Is selected.

Since the solid-free liquid separated from the culture used in the present invention is brought into contact with food or food material, the solid-free liquid does not contain any harmful substances, and after the contact treatment. It is necessary to confirm in advance that no harmful substances are generated in the foods or food materials of.

The solid-free liquid separated from the culture used in the present invention is an active factor which markedly reduces the heat resistance of various bacteria adhering to foods or food materials, particularly spores which are not easily sterilized by heat treatment. Contains. This spore heat resistance-decreasing activity factor has the property of losing its specific activity when heated at 80 ° C. under normal pressure for 10 minutes, and is presumed to be an enzyme-like active protein which is relatively unstable to heat.

Further, the details of the action mechanism of the same active factor are unknown, but the spores of the spores of the spores of the spores or the outer shell of the spores already released to the outside of the spores are subjected to modification such as destruction or dissolution, It is presumed that spore germination and spore germ growth are completely prevented even by heat treatment at a relatively low temperature.

As various germs adhering to foods or food materials, particularly spore-forming bacteria which are not easily sterilized by heat treatment, various kinds of bacteria can be mentioned. For example, Bacillus subtilis, Bacillus stearothermophilus, and the following test strains are listed.

In order to test and confirm the bactericidal effect of the present invention, Bacillus coagulans among various spore-forming bacteria
(Bacillus coagulans), Bacillus licheniformis (B
acillus licheniformis), Bacillus megaterium (Bac
illus megaterium) and foods or food materials, especially protein-processed foods, become anaerobic during storage, and the anaerobic spore producing bacterium Clostridium sporogenes is selected.

As the strains of these test spores, the following strains are preferably selected. Bacillus coagulans JCM
2257, RIKEN Institute of Conservation, Strain No .: JCM 22
57. Bacillus licheniformi
s) JCM 2505, special corporation RIKEN Preserved bacterium, strain number: JCM 2505. Bacillus megaterium AJ-12
72, Research Institute for Applied Microbiology, University of Tokyo, Strain number: IA
M 1245. Clostridium sporogenes
genes) JCM 1416, special corporation RIKEN conserved bacterium, strain number: JCM 1416.

In the present invention, the food or food material to be sterilized is not particularly limited. That is, the sterilization method of the present invention is applied to all plant foods or the same food materials, animal foods or the same food materials, and foods or food materials obtained by mixing the plant materials and the animal materials.

There is no particular limitation on the method for bringing the food or food material into contact with the solid-free liquid separated from the culture of the spore heat resistance-reducing active factor-producing microorganism. That is, any method such as immersing the food or food material in the solid-free liquid and spraying the solid-free liquid uniformly and evenly on the surface of the food or food material can be applied. It is appropriate that the contacting time is 1 minute or more and about 24 hours.

The temperature at which the food or food material is heated for the purpose of sterilization after contacting the solid-free liquid with the food or food material is selected from the range of 100 ° C. or less and 21 ° C. under normal pressure. If the heating temperature is within the above temperature range, the treatment temperature may be changed a plurality of times within the heating time. Also,
You may heat several times intermittently.

The heating time is determined by the type and state of the food or food material to be sterilized, but it is the same as or longer than the case where the same food or food material is conventionally heat sterilized at high temperature. A short time is enough. Alternatively, a slightly extended time may be adopted.

Although a bactericidal effect can be observed even if it is heated at a temperature exceeding the above-mentioned temperature range, it may cause changes in components, coloring, taste, and texture of the food or food material, which is preferable. Absent. On the other hand, the bactericidal effect is not remarkable when heated at a temperature lower than the temperature range.

The heating method is not particularly limited. That is,
The solid-free liquid and the food or food material may be heated in a state of being in contact with each other, or may be heated after the solid-free liquid is removed as completely as possible.

The sterilization temperature range in the present invention is significantly lower than the conventional heat sterilization temperature range, and sterilization can be sufficiently performed even at such a low temperature. Therefore, the food or food material heat-sterilized by the method of the present invention does not cause changes in components, changes in color tone, changes in taste, and changes in texture.

Any solid-liquid separation method can be applied and any solid-liquid separation device can be used to separate and obtain a solid-free liquid from a culture of a microorganism producing spore heat resistance-reducing active factor. However, since it is necessary to perform solid-liquid separation as quickly and completely as possible, the low-temperature high-speed centrifugal separation method and the solid-liquid separation apparatus are suitable. For example, below 5 ℃ at 3500 rpm
Centrifugation for about 10 minutes is appropriate.

As the culture medium for the microorganism producing spore heat resistance-reducing active factor, a medium conventionally used as a medium for the microorganism can be used. Since the spore heat resistance-decreasing active factor is often produced inducibly, adding the completely sterilized spores or spore extract in advance to the medium will result in the production rate and production of the spore heat resistance-decreasing active factor. The concentration can be improved.

The method for adding completely sterilized spores or spore extract to the medium is not particularly limited. For example, a dispersion prepared by dispersing spores sterilized with ethylene oxide in a buffer solution near pH neutral is used as a medium. Should be added to.

The present invention will be described below with reference to examples.
The following embodiments do not limit the technical scope of the present invention.

[0034]

【Example】

Example 1: This example is an example in which a low temperature heat sterilization effect on spores was tested using a spore heat resistance-lowering factor-containing liquid produced by filamentous fungi.

Bacteria used: a) Filamentous fungi producing spore heat resistance reducing factor: Gymnoascus reessii AJ-7
589 Deposited at the Institute of Biotechnology, Institute of Biotechnology, Ministry of International Trade and Industry Deposit number: FERM P-15443 b) Test spore bacterium: Bacillus coagulans JCM
2257 RIKEN Special Conserved Microorganism: Strain No. JCM 2257

Production of spore heat resistance-lowering factor-containing solution: The above spore heat resistance-lowering factor-producing bacterium was successively grown from the storage medium in the following steps to obtain a solid-free spore heat resistance-lowering factor-containing solution.

Preculture medium and preculture conditions for spore heat-resistance-decreasing factor-producing bacteria: Preculture medium: potato dextrose slope agar preculture conditions: static culture at 28 ° C. for 7 days

Refresh culture medium and culture conditions for the spore heat-resistance-decreasing factor-producing bacterium: Refresh culture medium composition: yeast extract 0.2% glucose 0.2% polypeptone 0.5% After adjusting the above-mentioned composition solution to pH 6.0, the temperature was increased to 20 at 121 ° C. Sterilized for a minute. Refresh culture conditions: 50 mL of refresh medium was dispensed into a sterilized 500 mL Sakaguchi flask, and 3 platinum loops of the precultured cells were inoculated, followed by shaking culture at 28 to 30 ° C for 3 days. The shaking conditions were an amplitude of 7 cm and 120 rpm.

Main culture medium and main culture conditions of spore heat-resistance-decreasing factor-producing bacterium: The culture solution obtained by the above-mentioned refresh culture was transferred to the following main culture medium and cultured under the main culture conditions.

Medium Composition of Main Culture Medium A: Yeast Extract 0.1% Glucose 1.0% Polypeptone 0.1% The above composition solution was adjusted to pH 7.0 and sterilized at 121 ° C. for 20 minutes.

Medium composition of main culture medium B: Bacillus coagulans (Bacillus) sterilized with ethylene oxide
Coagulans) JCM 2257 spores were adjusted to 0.4%, and the spores were adjusted to pH 7.0 and dispersed in 0.025M phosphate buffer sterilized at 121 ° C for 20 minutes.

Main culture conditions: Main culture medium A (25 mL) and main culture medium B (25 mL) were sterilized in a 500-mL Sakaguchi flask, and 2% of the culture solution previously cultured in the refresh medium was inoculated. Culture was carried out with shaking for a day. Shaking conditions are
The amplitude was 7 cm and 120 rpm.

Fractionation of active factor-containing solution from culture medium of spore heat-resistance-decreasing factor-producing bacterium: 4 above-mentioned main culture broths are combined and centrifuged at 5 ° C., 3500 rpm, 10 minutes. , 150 mL of the active agent-containing solution was obtained as the supernatant.

Contact of the solution containing the spore heat resistance-decreasing factor with the assay spore bacterium: the above-mentioned solution containing the active factor and the assay spore bacterium Bacillus coagulans JCM 2257
The spore dispersions were mixed and kept under the following spore germination and activation temperature conditions.

Preparation of Spore Dispersion of Test Spores, Test Solution, Blank Solution and Control Solution: (i) Spore Dispersion of Test Spores: 10 ⁷ to 10 ⁸ Spores of Test Spores / mL At a concentration of 0.02 M adjusted to pH 6.5
Dispersed in phosphate buffer. (ii) Test liquid: 1.0 mL of the spore dispersion liquid and 0.5 mL of the active factor-containing solution were dispensed into a sterilized test tube. (iii) Blank solution: 1.0 mL of the spore dispersion solution described above and 0.5 of sterilized water.
mL was dispensed into a sterilized test tube. (iv) Control solution: 1.0 mL of the spore dispersion and 0.5 mL of the active factor-containing solution kept at 80 ° C for 10 minutes were dispensed into a sterilized test tube.

Contact conditions between the spore heat resistance-lowering factor-containing solution and the spore dispersion of the spore-forming bacterium for assay: The above test solution, blank solution and control solution were kept at 45 ° C. for 30 minutes, 2 hours or 7 hours.

Heat treatment: over the specified time as above
The test solution, the blank solution and the control solution kept at 45 ° C were subjected to heat treatment (low heat load sterilization treatment) under the following conditions.

Heat treatment (low heat load sterilization treatment) and post-treatment conditions: Hold at 70 ° C. for 15 minutes. Immediately thereafter, rapidly cooled with ice water

Test method for bactericidal effect: A test solution, a blank solution and a control solution which have been subjected to heat treatment (low heat load sterilization treatment) are appropriately diluted with sterilized water, smeared and inoculated on a plate medium and cultured to determine the viable cell count Counted and calibrated.

Assay medium and assay culture conditions: i) Assay medium: Plate standard agar medium ii) Inoculation: Diluted test solution, blank solution and control solution were inoculated at 1 mL per plate standard agar medium iii) Assay Culture conditions: Hold at 35 ℃ for 7 days

Counting method of surviving bacteria after assay culture: The number of viable bacterial colonies was counted under the visual field.

Assay result: Table 1 shows the viable cell count concentration (cells / mL) calculated based on the counted viable cell colony count. Here, in the case of the control solution that had been previously held at 80 ° C for 10 minutes, almost the same number of viable bacterial colonies as in the blank solution was observed, and therefore the spore heat resistance-decreasing factor was almost completely inactivated by this preheating. It was determined that

In each of the following Examples 2 and subsequent Examples, as in Example 1, the same number of viable bacterial colonies as that of the blank solution was observed in the control solution, so that the same number of viable bacterial colonies as in the blank solution was observed.
The spore heat resistance-decreasing factor was judged to be almost completely inactivated, and the numerical value of the viable cell count concentration of the control solution was excluded from each table below Table 2.

[0054]

[Table 1]

Evaluation of test results: The values of the test plots in Table 1 and the values of the blanks were compared, and the degree of sterilization was expressed as a numerical value (digit) by the following mathematical formula. The low temperature heat sterilization effect was evaluated.

Numerical expression for evaluation of test results: logB-logT = logE, (displayed as an exact number corresponding to logE) where B is a blank value, T is a test group value, and E is a bactericidal effect value.

Assay results: Treatment with a liquid containing a spore heat resistance-decreasing factor, 45 ° C. × 2 hours / heat sterilization 70 ° C. × 15 minutes, 2.
It was a 5-digit sterilization.

Example 2 This example is an example in which a low temperature heat sterilization effect on spore-forming bacteria was tested using a spore heat-resistance reducing factor-containing liquid produced by filamentous fungi.

Purpose of this Example: In order to confirm the change in bactericidal effect when the content of yeast extract was changed (1/2 concentration) in the composition of the main culture medium, the "book" of Example 1 was used. The low temperature heat sterilization effect on the spore bacterium was tested by changing the "medium composition of the culture medium A" and the "contact condition between the spore heat resistance-lowering factor-containing solution and the spore dispersion liquid of the spore test bacterium" as follows.

Composition of main culture medium A after change: yeast extract 0.05% glucose 1.0% polypeptone 0.1%

Contact condition between the spore heat-resistance-lowering factor-containing solution and the spore dispersion liquid of the spore-forming bacterium for assay: The test solution, blank solution and control solution are kept at 45 ° C. for 2 hours.

Assay results: The viable cell count concentration (cells / mL) calculated based on the counted viable cell colony counts is shown in Table 2 below.

[0063]

[Table 2]

Evaluation of assay results: 3.0-digit sterilization was performed under the conditions of treatment with a liquid containing a spore heat resistance-lowering factor, 45 ° C. × 2 hours / sterilization heating 70 ° C. × 15 minutes. It was also confirmed that the bactericidal effect was not changed even if the yeast extract concentration was reduced by half in the composition of "main culture medium A".

Example 3 This example is an example in which a low temperature heat sterilization effect on spore-forming bacteria was tested using a spore heat-resistance reducing factor-containing liquid produced by filamentous fungi.

Purpose of this Example: In order to confirm the effect of low-temperature heat sterilization on spore-forming bacteria other than Bacillus coagulans, the "use bacterium: b) assay spore-forming bacterium of Example 1 was changed as follows. The low temperature heat sterilization effect on spores was tested.

Bacteria used: a) Filamentous fungi producing spore heat resistance-decreasing factor: (Same as in Example 1) Gymnoascus reessii AJ-7
589 Deposited at the Institute of Biotechnology, Institute of Biotechnology, Ministry of International Trade and Industry Deposit number: FERM P-15443 b) Test spore bacterium: (i or ii below) i) Bacillus lichenifor
mis) JCM 2505 RIKEN Special Conserved Microorganism, Strain No .: JCM 2505 ii) Bacillus megaterium I
AM 1245 Institute of Applied Microbiology, University of Tokyo Conserved microorganism, strain number: IA
M 1245

Assay results: The viable cell count concentration (cells / mL) calculated based on the counted viable cell colony counts is shown in Table 3 below.

[0069]

[Table 3]

Evaluation of assay results: Bacillus licheniformis 2.0 digit sterilization, and Bacillus megaterium sterilization under conditions of treatment with a liquid containing a spore heat resistance-decreasing factor, 45 ° C. × 2 hours / sterilization heating 70 ° C. × 15 minutes It was 2.1 digit sterilization. Therefore, the liquid treatment containing the spore heat resistance-decreasing factor of the present invention /
It was confirmed that the low temperature heat sterilization method was effective against various thermostable spores.

Example 4 This example is an example in which the low temperature heat sterilization effect on spore-forming bacteria was tested using a spore heat-resistance reducing factor-containing liquid produced by filamentous fungi.

Purpose of this Example: In order to confirm the effect of low temperature heat sterilization on spore-forming bacteria other than Bacillus coagulans, especially anaerobic spore-forming bacteria, "use bacteria: b) assay spore-forming bacteria" and "of bacterium" of Example 1 The assay medium and assay culture conditions "were changed as follows, and the low temperature heat sterilization effect on anaerobic spore bacteria was assayed.

Bacteria used: a) Filamentous fungi producing spore heat resistance-decreasing factor: (same as in Example 1) Gymnoascus reessii AJ-7
589 Deposited at the Institute of Biotechnology, Institute of Biotechnology, Ministry of International Trade and Industry Deposit number: FERM P-15443 b) Test spore bacterium: Clostridium sporogenes JCM 1416 Special corporation RIKEN Preserved microorganism, strain number: JCM 1416

Assay medium and assay culture conditions: i) Assay medium: GAM agar medium ii) Assay culture conditions: GAM agar medium was smeared and inoculated, and then cultured at 35 ° C. for 5 days under anaerobic conditions.

The assay medium, GAM (Gifu Anearob
The ic medium) agar medium is prepared by adding 2.0% of agar to "GAM-bouillon" which is a regular medium for anaerobic bacteria. The composition of "GAM-bouillon" is described in books on microbiology, for example, "Toda Shin Bacteriology", 29th edition, page 837 (198).
8) It is described in [Nanzandou Publishing].

Assay results: The viable cell count concentration (cells / mL) calculated based on the counted viable cell colony counts is shown in Table 4 below.

[0077]

[Table 4]

Evaluation of assay results: Clostridium sporogenes was 1.9-digit sterilization under the conditions of treatment with a liquid containing a spore heat resistance-decreasing factor, 45 ° C. × 2 hours / sterilization heating 70 ° C. × 15 minutes. Therefore, it was confirmed that the spore heat resistance-decreasing factor-containing liquid treatment / low-temperature heat sterilization method is effective against anaerobic heat-resistant spore bacterium.

Example 5: This example is an example in which a low temperature heat sterilization effect on spore-forming bacteria was assayed using a spore heat-resistance reducing factor-containing liquid produced by filamentous fungi.

Purpose of this example: The "refresh culture medium composition" and "main culture medium composition and main culture conditions" of Example 1 were changed as follows to test the effect of low temperature heat sterilization on spores of Bacillus coagulans. did.

Composition of refreshing medium: yeast extract 0.1% glucose 1.0% polypeptone 0.1% The above composition solution was adjusted to pH 7.0 and sterilized at 121 ° C. for 20 minutes.

Composition of main culture medium: A 2.0% culture solution (inoculum) of Jimnoascus racey AJ-7589 cultured in a refreshing medium was used. i) Potato dextrose liquid medium 50 mL Aliquot 50 mL of the above composition liquid into a 500 mL sterilized Sakaguchi flask and sterilize at 121 ° C for 20 minutes. pH is not adjusted. Incidentally, potatoes
Dextrose liquid medium can be found in "JCM Catalog of Strain
s, 5th Ed., p.394, No. 30 (RIKEN, published in 1992) ”, which is a medium obtained by removing agar from the medium composition. ii) Potato dextrose liquid medium 25 mL pH 7.0, 0.025 M phosphate buffer 25 mL (sterilized at 121 ° C for 20 minutes) 500 mL of 50 mL solution prepared by mixing 25 mL of each of the above individual solutions
Dispense into a sterilized Sakaguchi flask.

Culture conditions for main culture: i) or ii) above.
50 mL of the main culture medium of was cultured with shaking at 28 to 30 ° C. for 2 days.

Assay results: The viable cell count concentration (cells / mL) calculated based on the counted viable cell colony counts is shown in Table 5 below.

[0085]

[Table 5]

Evaluation of assay results: Treatment with a liquid containing a spore heat resistance-decreasing factor, under conditions of 45 ° C. × 2 hours / sterilization heating 70 ° C. × 15 minutes, 2.8 digit sterilization in the main culture medium of i), ii) of the book The culture medium was 1.9-digit sterilization. Therefore, it was confirmed that the spore heat resistance-decreasing factor-containing liquid treatment / low-temperature heat sterilization method is effective against anaerobic heat-resistant spore bacterium. It was also confirmed that the effect of low-temperature heat sterilization did not substantially change even if the concentration of the components of the refreshing medium was changed or the components of the main culture medium were changed.

Example 6 This example is an example of assaying the effect of low temperature heat sterilization on spores of Bacillus coagulans using a spore heat resistance reducing factor-containing solution produced by filamentous fungi.

Purpose of this Example: It was confirmed that the composition of the main culture medium was not changed, that is, there was no substantial change in the low temperature heat sterilization effect even if the ethylene oxide sterilized spores of Bacillus coagulans were not added. In order to
The "main culture medium composition and main culture conditions" of Example 1 were changed as follows, and the low temperature heat sterilization effect on the spore bacterium was tested.

Main culture medium composition (no spores added): 2.0% amount of the culture solution of Jimnoascus lacey AJ-7589 cultured in a refreshing medium, a composition solution of the "main culture medium composition" solution of Example 1 only in A medium 50 mL was collected and the pH was not adjusted.

Assay results: The viable cell count concentration (cells / mL) calculated based on the counted viable cell colonies is shown in Table 6 below.

[0091]

[Table 6]

Evaluation of assay results: When the composition of the main culture medium was changed under the conditions of treatment with a liquid containing a spore heat resistance-decreasing factor, 45 ° C. × 2 hours / sterilization heating 70 ° C. × 15 minutes, 2.5-digit sterilization was performed. there were. Therefore, it was confirmed that the effect of low-temperature heat sterilization did not substantially change even if the components of the main culture medium were changed.

Example 7: This example is an example in which a low temperature heat sterilization effect on spore-forming bacteria was tested using a spore heat-resistance-lowering factor-containing liquid produced by filamentous fungi.

Purpose of this example: In order to confirm that the low-temperature heat sterilization effect is improved by treating the spore heat resistance-decreasing factor-containing liquid with a spore heat resistance-decreasing factor-containing liquid in which a lytic enzyme coexists. A lytic enzyme was allowed to coexist in the "spore heat resistance-lowering factor-containing solution" of Example 1 as described below, and the effect of low temperature heat sterilization on spore bacteria was tested.

Composition of spore heat resistance lowering factor-containing solution coexisting with lytic enzyme and additional treatment conditions: 1 mL of a 0.25% concentration lysozyme solution was added to the "spore heat resistance lowering factor-containing solution" of Example 1 Hold at 45 ° C for 2 hours.

Assay results: The viable cell count concentration (cells / mL) calculated based on the counted viable cell colony counts is shown in Table 7 below.

[0097]

[Table 7]

Evaluation of assay results: Treatment with a liquid containing a spore heat resistance-decreasing factor, under the conditions of 45 ° C. × 2 hours / sterilization heating 70 ° C. × 15 minutes, when a lysozyme solution was added for additional treatment,
It was 3.7 digit sterilization. Therefore, it was confirmed that when the lysing enzyme was allowed to coexist, the low temperature heat sterilization effect was remarkably improved as compared with the case where the solution containing the spore heat resistance-decreasing factor-containing solution was treated alone.

[0099]

As described above, according to the present invention, a culture of a microorganism such as a filamentous fungus contains a spore heat resistance-lowering factor, and after contacting the spore heat resistance-lowering factor solution with a food or food material, By carrying out the low-temperature heat treatment, it is possible to effectively sterilize the food or food material without impairing the taste or texture of the food or food material.

Claims (2)

[Claims] 1. A food or food material in which a spore-forming microorganism is present is contacted with a solid-free liquid separated from a culture of filamentous fungi, yeast, bacteria or actinomycetes, and then at 100 ° C.
Hereinafter, a sterilization method for foods or food materials, which comprises heating to 21 ° C or higher. 2. The sterilizing method according to claim 1, wherein the filamentous fungus is a filamentous fungus belonging to the genus Gymnoascus.