JPH05146282A - Antibacterial agent - Google Patents

Abstract

PURPOSE:To provide an antibacterial agent acting synergistically at a low level, capable of preventing food deterioration effectively for a long period of time without food taste or flavor when used as a food additive, thus useful for e.g. a preservative for deteriorative foods, containing, as active ingredients, nisin and a hydrophilic surfactant. CONSTITUTION:The objective antibacterial agent having the above-mentioned advantages, containing, as active ingredients, (A) nisin, an antimicrobial peptide which can be produced by a strain like Streptococcus lactis, made up of 34 amino acids including lanthionine, dehydroalanine and beta-methyllanthionine, stable to heat, and having growth-inhibitory activity on Gram-positive bacteria and (B) a hydrophilic surfactant (e.g. sucrose fatty acid ester).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an antibacterial agent which inhibits the growth of microorganisms and is particularly suitable for the preservation of foods.

[0002]

2. Description of the Related Art Due to the recent development of a distribution system, processed foods can be supplied to a wide range. Along with this, it has become desirable to store foods for a long time. There are various food preservatives such as organic acids, inorganic acids, alcohols, chemically synthesized products, and those derived from natural products. Nisin (NISIN) is Streptococcus lacti.
s) and other antimicrobial peptides produced by such strains. Nisin is composed of 34 amino acids including lanthionine, dehydroalanine, and β-methyllanthionine in the molecule. Nisin is stable against heat and exhibits a growth inhibitory effect particularly against Gram-positive bacteria. This peptide has been confirmed to be biodegradable, and has been used as a highly safe antibacterial agent in dairy products for a long time in Europe. Although the mechanism of action of nisin has not been elucidated, it is generally considered to act on the cell membrane [Henning et al., Int. J. Food Micr
obiol. 3, 121-134 (1986)].

Nisin is mainly used as a food additive in Europe, and is used for low temperature and short-term storage represented by dairy products such as processed cheese, bakery food, canned goods, mayonnaise and cream. There is. The amount added is limited to about 500 iu / g. In order to exhibit sufficient antibacterial properties even at room temperature or high temperature, it is necessary to use a large amount of expensive nisin, which has not been realized. For example, storing milk coffee at 55 ° C. for about 50 days requires as much as about 1000 iu / g nisin.

On the other hand, some of the surfactants are widely used as food additives in dairy products, wheat flour products, dairy products, confectionery products, processed oil and fat products and the like. Among these surfactants, there are some which are recognized to have an antimicrobial effect such as sucrose fatty acid ester and polyglycerin fatty acid ester [Suwa et al., Journal of Japan Food Industry Society, 33, 4].
4-51 (1986)]. In particular, fatty acid esters such as shou are added to low-acid canned foods and the like, and are widely used for preventing deterioration of foods.

[0005]

However, nisin is expensive, and there is a problem that the cost of food increases when it is added to food etc. by itself. In addition, food-grade surfactants such as sucrose fatty acid esters generally increase the cost of foods when added in large amounts, and at the same time unfavorably adversely affect the taste and flavor of foods, and foods such as starch-containing foods. Depending on the situation, there was a problem that the effect was not fully exhibited. Therefore, it has been desired to develop an antibacterial agent that effectively suppresses the growth of microorganisms with a smaller amount and at a lower cost.

[0006]

Means for Solving the Problems In view of the above points, the present inventors have earnestly studied, and as a result, by using a combination of nisin and a hydrophilic surfactant, the synergistic effect thereof remarkably suppressed the growth of microorganisms. The present invention has been completed and the present invention has been completed. That is, the present invention resides in an antibacterial agent containing nisin and a hydrophilic surfactant as active ingredients. Although the mechanism of synergism between nisin and the surfactant is not clear, it is expected that the surfactant facilitates the access of nisin to the membrane of the microorganism, which is believed to be the site of action of nisin.

The nisin used in the present invention may have any effective antibacterial activity and may contain other components. Further, the effect of the present invention is not sufficiently exerted with a surfactant having a low HLB value having a low degree of hydrophilicity. Therefore, examples of the surfactant suitable for the present invention include hydrophilic surfactants composed of polyol fatty acid esters such as sucrose fatty acid ester, polyglycerin fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.
The HLB value of the surfactant is usually 8 or more, preferably 10 or more. Examples of the fatty acid that constitutes the polyol fatty acid ester include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and behenic acid, which are saturated or unsaturated fatty acids having 8 to 22 carbon atoms. One kind or a mixture of two or more kinds may be mentioned. The average degree of ester substitution of these polyol fatty acid esters is usually 1 to 5, preferably about 1 to 3. These hydrophilic surfactants may be used alone or in combination of two or more. Among the above surfactants, the effect of sucrose fatty acid ester is particularly strong and most suitable.

The ranges and ratios of the amounts of the hydrophilic surfactant and nisin added are not particularly limited, but the hydrophilic surfactant is usually 0.0001 to 1% by weight relative to the target food,
Nisin is generally added at 1 to 5000 iu / g. Preferably, considering the effect, price, and influence on taste, the hydrophilic surfactant is 0.005 to 0.1% by weight,
Addition of nisin 50 to 500 iu / g is preferred. The type of food to be added is not particularly limited, but examples thereof include beverages such as milk coffee, shirko and soup; dairy products such as cheese and fresh cream; canned vegetables such as tomatoes; mayonnaise, soup sauce,
Seasonings such as miso; noodles such as udon, Japanese soba, Chinese buckwheat; water-mixed products such as kamaboko and bamboo rings; meat products such as sausages and hams; prepared foods such as shumai, gyoza, hamburger; confectionery, etc. .. The method of adding the antibacterial agent of the present invention to food is not particularly limited, and nisin and a hydrophilic surfactant may be added separately, or a mixture of nisin and a surfactant in advance may be added. When processing food, it may be added at any stage of processing.

It is preferable that the amount of the antibacterial agent containing nisin and the surfactant as active ingredients is appropriately adjusted depending on the kind of food to be added. The preferable amount of the antibacterial agent added can be determined according to the amount conventionally required for nisin by converting the antibacterial activity into the amount of nisin. For example, milk 30-50 iu / g (cryopreservation), processed cheese 500 iu / g, solid cream 150 iu / g,
Canned vegetables 200 iu / g, alcoholic beverages 100 iu /
g (both stored at room temperature) and the like are conventionally added amounts calculated in terms of nisin. In addition, since nisin is expensive, a large amount of nisin has not been added by itself, but it can be used for milk coffee etc. stored at high temperature.
The antibacterial agent of the present invention can be added in a small amount and at a low price.

[0010]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples unless it exceeds the gist. Examples include Nisin as Aprin & Barrett.
Rett's Nisaplin was used, and the surfactants shown in Table 1 were used. Examples 1-2 and Comparative Examples 1-5 Bacillus stearothermophilus (Bacillus)
Stearothermophilus) growth inhibition test

The synergistic effect of nisin and the hydrophilic surfactant was confirmed by the paper disk method. As shown in Table 2 below, an aqueous solution (pH 6.5) containing nisin and / or a hydrophilic surfactant at each concentration was prepared. Then trypton nutrient
140 μ of the above aqueous solution on a paper disc containing t)
Bacillus that had been prepared in advance.
It was placed on the surface of saline agar medium containing stearothermophilus and inverted and incubated overnight at 55 ° C. The diameter of the clear and pronounced zone of inhibition observed around the disc was measured. The antibacterial activity (inhibitory activity) of each solution was converted to nisin activity using a calibration curve prepared from the concentration of the standard solution of nisin and the diameter of the inhibition zone. The results are shown in Table 2 below.

Each of the hydrophilic surfactants alone showed almost no antibacterial activity at several thousand ppm, but 100 iu /
The coexistence of g of nisin showed a higher antibacterial activity than the arithmetic sum of hydrophilic surfactants. Similarly, when nisin coexisted with the hydrophilic surfactant, the nisin-equivalent activity showed higher antibacterial activity than the arithmetic sum thereof, as compared with the activity of nisin alone. Therefore, it was found that the synergistic effect was remarkable.

Example 3 Clostridium thermaceti in milk coffee
(cum) Spore growth inhibition test The raw materials shown in Table 3 below were added to water, heated and dissolved at 60 to 70 ° C., homogenized by a homogenizer, and then pH 6.8.
Milk coffee was prepared.

The milk coffee thus obtained is then mixed with Clostridium thermoacecum, which is one of the bacteria causing deterioration.
Ticum) spores were inoculated to a final concentration of 2.0 × 10 ⁵ / g. 2 ml of each of these was put into a thick glass test tube and sealed by melting. 10 by bath at 121 ℃
After heat sterilization for 30 minutes, incubation was carried out at 55 ° C. for 32 or 48 days, and the pH decrease of milk coffee due to bacterial growth was measured to examine the presence or absence of spoilage. A drop in the pH of milk coffee indicates its deterioration. Tables 4 to 6 show the number of test tubes that caused a pH drop in each of the five test sections, that is, the number of spoilage test tubes.

As shown in Tables 4 to 6, the antibacterial agent required for milk coffee has a nisin conversion activity (that is, the amount of nisin required when nisin is used alone).
It is 1000 iu / g when stored for 48 days and 300 iu / g when stored for 32 days. On the other hand, it was found that only 33 niu / g of nisin and 200 ppm of sucrose fatty acid ester had antibacterial properties equivalent to a nisin-equivalent activity of 1000 iu / g. Similarly, nisin 100 iu / g and polyglycerin fatty acid ester 300 ppm or nisin 33 iu / g and polyglycerin fatty acid ester 400 p
In pm, there was an antibacterial property equivalent to a nisin conversion activity of 300 iu / g, and a clear synergistic effect was observed. On the other hand, with regard to glycerin monofatty acid ester having a low hydrophilicity, the improvement of the effect by the combined use with nisin was not observed.

Example 4 Clostridium thermoaceticum in Shirushi Beverage
um) Growth control test of spores Granulated sugar, corn starch, salt, sucrose fatty acid ester, and nisin in the amounts shown in Table 3 below were mixed, water was added, and the mixture was heated to 80 ° C. To this, overnight, soaked bean jam soaked in water was added, and the mixture was further heated to 80 ° C. to prepare a shirushi drink (pH 6.
8) was obtained. An experiment was conducted in the same manner as in Example 3 except that the final spore concentration was 1.2 × 10 ⁵ / g and the number of storage days was 21 days.

Conventionally, in foods containing starch, even if sucrose fatty acid ester was added at a high concentration of about 2000 ppm, its deterioration could not be prevented. In addition, as a result of the experiment, a nisin conversion activity of 600 iu / g was required to prevent spoilage in the shiruko beverage. However, as shown in Table 7 below, it was found that 200 iu / g of nisin and 200 ppm of sucrose fatty acid ester exhibited sufficient antibacterial properties, and it was confirmed that spoilage can be prevented at a practical level in terms of cost and flavor. Was done. Examples 5 to 15 A growth inhibition test was conducted in the same manner as in Examples 1 to 2 and the results shown in Table 8 were obtained. Comparative Examples 6 to 20 The growth inhibition test was conducted in the same manner as in Examples 1 and 2, and the results in Table 9 were obtained.

[0018]

INDUSTRIAL APPLICABILITY The combination of nisin and the hydrophilic surfactant of the present invention showed synergistic antibacterial action in a small amount as compared with the case where each of them was used alone. Therefore, even when it is added to food, it is possible to effectively prevent spoilage over a long period of time without affecting the taste and flavor by adding a small amount.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

[Table 5]

[0024]

[Table 6]

[0025]

[Table 7]

[0026]

[Table 8]

[0027]

[Table 9]

Claims (3)

[Claims] 1. An antibacterial agent containing nisin and a hydrophilic surfactant as active ingredients. 2. A spoilage-resistant food containing nisin and a hydrophilic surfactant. 3. A method for preventing spoilage of foods, which comprises adding nisin and a hydrophilic surfactant to the foods.