JP2002369678A - Method for preventing sundry germs for malted rice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing sundry germs for malted rice, effectively suppressing spore-forming bacteria in producing malted rice for producing high-quality fermented foods having no dry grass smell, such as fermented bean paste, soy sauce, refined rice wine. SOLUTION: This method comprises adding a lactic fermentation liquid containing bacteriocin and water-soluble calcium or water-soluble magnesium to prevent proliferation of sundry germs in an incubation process when producing malted rice by boiling cereals or beans, cooling the resultant product and inoculating Aspergillus oryjae thereinto. The lactic fermentation liquid and the water-soluble calcium or water-soluble magnesium are added with time difference and, if the lactic fermentation liquid is added first, a better effect can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing koji by inoculating a koji mold into cereals such as rice and wheat after steaming, and removing remaining spores and other contaminating bacteria into lactic acid containing bacteriocin. The present invention relates to a method for preventing various bacteria of koji, which is effectively sterilized by using a fermentation solution and calcium ions and / or magnesium ions in combination.

[0002]

2. Description of the Related Art Koji is an intermediate raw material of the final fermented food by steaming cereals such as rice and barley and beans such as soybeans, and allowing it to cool, then inoculating the koji mold to decompose carbohydrates and proteins with enzymes generated by the koji mold. It is what becomes. Therefore, the quality of koji directly affects the quality of the final product. Good quality koji is germs,
In particular, it is important that fermentation is carried out in a state in which the koji mold forms a predominant bacterial flora without being contaminated by spores, and that other koji bacteria are inhibited and only the koji mold is propagated.

Hitherto, it has been known that the growth of harmful bacteria is suppressed while lactic acid bacteria survive, and that the koji mold is not affected at all. Recently, a method has been developed in which certain lactic acid bacteria produce an antibacterial substance called bacteriocin, and this bacteriocin is added to food to prevent spoilage of food under mild conditions. On the other hand, when spores form spores, 10
It is not sterilized under general sterilizing conditions of 0 ° C. or less, and germinates and starts growing when the environment becomes favorable. In general, when spores grow, an unpleasant odor is emitted, and the flavor of the koji in which the spores grow is reduced. And while bacteriocin is effective on vegetative cell types of spores, it has no bactericidal effect on spores. 100 ℃
The heat sterilization under pressure exceeding the above-mentioned temperature causes so-called retort odor, and at the same time, deteriorates the flavor of food, such as taste, texture and color. Therefore, it cannot be adopted in a general food manufacturing process in many cases.

[0004]

As described above, the quality of koji depends on how to suppress the growth of various bacteria including spores during the cultivation of the koji mold. Although bactericidal activity is weak, bacteriocin, which is derived from natural products and acts under mild conditions, is a preferable bacteriostatic agent, but has a problem in persistence of efficacy and has not yet been actually used.
The present inventors, regarding the koji for which high-temperature pressure treatment is not preferred,
The long-lasting effect of lactic acid fermentation broth containing nisin belonging to bacteriocin as an active ingredient was studied. It is known that the activity of nisin is significantly reduced in the presence of a cation having a valency of II or III such as magnesium ion and calcium ion (Koshobo, Biopreservation,
69-70).

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the structure of the process is as follows. In producing koji by steaming cereals or legumes, inoculating koji mold after cooling, and producing koji. A lactic acid fermentation solution containing bacteriocin and water-soluble calcium or water-soluble magnesium are added to prevent the propagation of various bacteria, and the time difference between the lactic acid fermentation solution and water-soluble calcium or water-soluble magnesium is maintained. And add. A further effect can be obtained by adding the lactic acid fermentation solution first.

The present inventors conducted tests to confirm the above-mentioned known facts, and surprisingly, coexistence of calcium ions and lactic acid fermentation solution significantly improved the efficacy of lactic acid fermentation solution.
The present inventors have found that high-quality koji can be produced, and have completed the present invention. Bacteriocins are generally fast-acting and have a bactericidal effect, but tend to be less effective on their own, tend to decrease in potency while in contact with steamed cereals for a long time and allow the growth of subsequent germs . Calcium, on the other hand, has no immediate effect but tends to maintain its efficacy, and the intended purpose could be achieved by using both together. That is, a remarkable effect was observed particularly when calcium ions were added with a time difference of 10 minutes to 4 hours after the lactic acid fermentation solution was added and cultured.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Koji is made by fermenting cereals such as rice, wheat, corn and beans such as soybeans using edible mold, saccharifying starch, and intermediate raw materials for fermented foods such as sake, miso and soy sauce. Is what you do. Good quality koji is the final product of sake, miso,
It greatly contributes to improving the quality of fermented foods such as soy sauce. Edible molds include Rhizopus and Muco
r), Aspergillus, Neurospora, etc., which mainly produce amylase and protease. The production of koji is that the spores remain only by boiling the raw materials, the process is performed in an open system, so that various bacteria in the air tend to be mixed, and the culture conditions of koji are suitable for the growth of various bacteria. For this reason, various kinds of bacteria are mixed in the koji, which tends to inhibit the original flavor of the koji.

The lactic acid fermentation solution used in the present invention is obtained by fermenting and growing lactic acid bacteria (Lactococcus lactis) producing bacteriocin, and the culture solution contains bacteriocin. Such lactic acid bacteria include nisin A
Lactis, Lactococcus lactis subsp. Cremoris, Lactoco
ccus lactis subsp. chacetilactis and the like. For example, Lactococcus lact producing nisin Z
is IO-1 (JCM 7638) can be seeded by culturing it in a TGC medium, and can be used as a seed indefinitely by storing it in a refrigerator as it is. As a medium, whey, starch saccharified solution, food grade glucose and the like can be used as a carbon source, and as a nitrogen source, degradation products of whey protein concentrate,
Corn peptide, soy peptide, commercial seasoning liquid raw material, shochu lees, food yeast extract and the like can be used. From the obtained lactic acid fermentation broth, only the medium supernatant was recovered by centrifugation, and the titer was used as a standard (Nisin, ICN Biomedical).
Is expressed in U / g on the basis of. In some cases, the lactic acid fermentation solution may be dried and used in a dry state.

When the lactic acid fermentation solution has a high titer or a thin solution can be used depending on the application, it can be used as it is, but preferably it is concentrated. Although various methods for concentrating nisin Z have been proposed, a membrane concentrating method using a charged reverse osmosis membrane made of polysulfone is industrially advantageous.
Concentrate it more than twice and use it at about 10,000 U / g. Further, the lactic acid fermentation broth can be roughly purified and used. Although various purification methods have been proposed, a method using a cation exchanger is an industrially preferable method. Various cation exchangers are also on the market, but select one that completely absorbs and elutes bacteriocin.

The present inventors have found that divalent cations, particularly calcium ions and magnesium ions, are effective as substances used in combination with bacteriocin. It is effective to add both to the koji at the same time, but it is more effective to add either one with a time delay. The time difference is 1
The time is 0 minute to 4 hours, and 20 minutes to 3 hours, more preferably 30 minutes to 2 hours in consideration of operational convenience and effects. Also, adding bacteriocin first and adding a divalent cation later provides more excellent effects than adding a divalent cation first.

The amount of calcium to be added is 0.1% as Ca.
It is from 0.01 to 2%, preferably from 0.05 to 1%. If it exceeds 2%, the flavor of the koji is adversely affected, and if it is less than 0.01%, a sufficient effect cannot be expected. Generally, a water-soluble calcium salt is used, and calcium chloride is preferably used. Also, water-soluble magnesium salts can be used.

Example 1 (1) Preparation of lactic acid fermentation broth Lactococcus lactis IO-1 (JCM 7638) was inoculated on a standard agar medium. The culture was performed under aerobic conditions or a facultative anaerobic condition by supplying 25% or less of oxygen that had been filtered and sterilized. The rotation speed was 250 rpm, and the culture temperature was about 3.
The cells were cultured at 0 ° C. for 15 hours. The resulting culture was Nisin Z
It had an activity of about 3500 U / g. The supernatant of the obtained culture is subjected to 20 to 4 at 7000 to 10000 rpm.
Centrifuge for 0 minutes, collect only the supernatant, and concentrate with concentrated hydrochloric acid.
Adjusted to 3.0 ± 0.5, left at 4 ° C. for 24 hours,
The mixture was centrifuged at 000 to 10000 rpm for 20 to 40 minutes, and concentrated using a polysulfone ultrafiltration membrane by a 100% nitrogen gas pressurization method. As a result, the lactic acid fermentation liquid was concentrated 3 to 5 times, and a concentrated liquid of about 10,000 U / g was obtained.

(2) Production and Testing of Koji 500 g of commercial soybeans were removed and thoroughly washed with water. 1.8
One liter of water was added, and the mixture was allowed to stand overnight to absorb water. Then, the husks were removed, transferred to a pot together with the immersed water, and steamed for 1 hour over low heat. The steamed soybeans were drained and coarsely ground. Next, 1 g of commercially available koji mold powder was added and mixed well. After mixing, 10 nisin Z of Lactococcus lactis IO-1 produced in (1) was used.
A concentrated solution of 000 U / g was added to 2% of the total amount, mixed, and cultured at 30 ° C. One hour later, a 10% aqueous calcium chloride solution was added so as to make up 5% of the whole. The koji was further cultured at 30 ° C. for 47 hours. The resulting koji-fermented soybeans had a sweet aroma and were white to ocher. The koji was completed after 48 hours of cultivation,
The cells were stored at 5 ° C. for a day, and the number of general viable bacteria, the number of bacteria in a Bacillus selective medium, the number of edible fungi, the number of coliforms and gram-negative bacteria were measured every 24 hours.

Separately, as a comparative example, koji (blank) produced in the same manner as in Example 4 except that neither the lactic acid fermentation solution nor calcium chloride was added, and the same procedure as in Example 4 except that calcium chloride was not added. Example 4 except that the koji (lactic acid fermentation liquid) produced by the above method and the lactic acid fermentation liquid were not added.
For the koji (CaCl ₂ ) produced in the same manner as in Example 4, the number of general viable bacteria, the number of bacteria in the Bacillus selective medium, the number of edible fungi, the number of coliforms,
The numbers of Gram-negative bacteria are also shown in Tables 4 to 7, respectively.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3] Edible mold count

[0018]

[Table 4]

[0019]

According to the present invention, it is possible to obtain a koji having a rich flavor of koji mold, in which contamination by various bacteria, especially spores, is suppressed. When this koji is used to produce various fermented foods such as miso, soy sauce, sake, etc., high quality fermented foods without hay odor can be obtained.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenjiro Ogura 5-27-5 Matsushima, Higashi-ku, Fukuoka City Fukuoka Prefecture (72) Sayaka Soma Inventor 5-27-5 Matsushima, Higashi-ku Fukuoka City, Fukuoka Prefecture (72) Inventor Harumi Nomiyama 5-27-5 Matsushima, Higashi-ku, Fukuoka City, Fukuoka Prefecture Incorporated Company (72) Inventor Yasuhide Tanimoto 1-38-1 Shinkatsutachi-cho, Omuta-shi, Fukuoka O Mu Dairy Co., Ltd. (72) Inventor Kenji Sonomoto 6-10-1 Hakozaki, Higashi-ku, Fukuoka F-term in Kyushu University (Reference) 4B065 AA60X BB02 BB19 BB40 CA41

Claims (5)

[Claims] 1. A method of producing a koji by steaming cereals or beans and inoculating a koji mold after cooling, adding a lactic acid fermentation solution and water-soluble calcium or water-soluble magnesium during the koji culturing process to propagate various bacteria. A method for preventing various germs of koji, comprising the steps of: 2. The method according to claim 1, wherein water-soluble calcium or water-soluble magnesium is added with a time lag after adding the lactic acid fermentation liquid. 3. The method according to claim 1, wherein the fermented lactic acid solution is added with a time lag after adding water-soluble calcium or water-soluble magnesium. 4. The method according to claim 1, wherein the lactic acid fermentation solution and water-soluble calcium or water-soluble magnesium are simultaneously added. 5. The method according to claim 1, wherein the lactic acid fermentation broth contains bacteriocin.