JPH05268975A - Production of streptococcus lactis culture product having bacteriostatic property - Google Patents

Abstract

PURPOSE:To obtain the subject culture product exhibiting a bacteriostatic action on heat-resistant bacteria with a small amount and capable of enhancing the preservability of foods without deteriorating their flavors by culturing Streptococcus lactis in a medium containing potato ingredients and a nitrogen source comprising corn-steep liquor and a yeast extract. CONSTITUTION:The production of the objective highly active culture product exhibiting a bacteriostatic action on heat-resistant bacteria with a small amount and capable of enhancing the preservability of foods without deteriorating their flavors comprises inoculating Streptococcus lactis IFO 12007 into a medium containing potato ingredients and a nitrogen source comprising corn-steeped liquor and/or a yeast extract to give the microbial cell density of 1wt.%, subjecting the inoculated cells to a standing culture at 30 deg.C for 24hr, removing the cells by centrifugation or filtration, disinfecting or sterilizing the filtrate by a thermal treatment at a temperature of 60-121 deg.C, and subsequently subjecting the treated solution to a lyophilization, spray drying, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing Streptococcus lactis cultures having effective bacteriostatic properties for foods in general, and starch-containing foods in particular.

[0002]

2. Description of the Related Art Certain Streptococcus lactis are known to produce peptidic bacteriostatic substances. However, in general, in order to obtain a highly active culture, Brain Heart Infusion (BHI) medium or a semi-synthetic medium containing peptone and the like and inorganic salts is used. When used in foods, it often causes a marked deterioration in flavor.

On the other hand, when a milk component (for example, skim milk powder) is added with a carbon source (for example, glucose) that can be assimilated by Streptococcus lactis, and the culture is carried out and the culture is used for food, there is almost no effect on the flavor. I will not give it,
The activity of the culture itself is low and it is difficult to use it for food.

Further, the activity of the culture could be improved by using the medium in which the milk component and the potato component were combined, but the addition did not cause any problems in flavor and texture when actually added to foods. In terms of quantity, it cannot be effective.

[0005]

That is, the object of the present invention is not to affect the flavor of canned beverages, side dishes, etc., and
It is to establish a method for producing an inexpensive Streptococcus lactis culture having high bacteriostatic activity.

[0006]

Means for Solving the Problems The present invention is a streptococcus having bacteriostatic properties characterized by using a medium in which a potato source and a corn steep liquor and a yeast extract are used alone or in combination with a nitrogen source. It is a method for producing a lactis culture.

Streptococcus lactis ( Str
Eptococcus lactis ) is a known lactococcus lactococcus commonly found in milk.

As the nitrogen source of the medium used in the method for producing the bacteriostatic culture of the present invention, corn steep liquor (total nitrogen of about 2.7) is used as 100% by weight of the entire medium (hereinafter abbreviated as%). In the case of yeast extract (about 9% of total nitrogen), it can be used in the range of 0 to 5%, preferably 0.5 to 2%. It can be used in the range of 0.1% to 0.5%. And the total amount thereof is 0.05 to 6%, preferably 0.1 to 3%.

The potato component is obtained by crushing potato which has been heat-processed such as boiling and steaming (dry weight of 0.1 to 0.1).
10%, preferably 1 to 5%), and an appropriate amount of such broth or hot water extract can also be used.

Further, commercially available potato dextrose or mashed potato containing potato components is used.
It may be used in place of potato in the range of 0.1 to 5%, preferably 0.5 to 2%.

The bacteriostatic culture of the present invention is prepared, for example, as follows.

The above ingredients are added to water to adjust the pH to 5.0-
7.5, preferably adjusted to 6.0-7.0, and a seed culture of Streptococcus lactis cultured in the same medium for 12 to 24 hours by a conventional method was added to this medium at 0.5%.
Inoculate to ~ 5%. This is stored at 20 ° C to 40 ° C, preferably 25 ° C to 37 ° C for 8 to 48 hours, preferably 1
A bacteriostatic culture is obtained by culturing for 2 to 24 hours.

The culture of the present invention is a solution obtained by removing Streptococcus lactis by centrifuging or filtering the culture as it is, or sterilized or sterilized by heat treatment at 60 ° C to 121 ° C. Used in liquid form. Furthermore, cultures include those subjected to processing such as freeze-drying and spray-drying.

When these cultures are placed in liquid, semi-liquid, paste-like products, the bacteriostatic activity is, for example, 10 I.V. U. / Ml or 10I. U. / G may be added so that the amount is at least g.

The unit of activity (I.U.) is nisin standard substance (Aplin & Bar) which is a bacteriostatic substance known to be produced by Streptococcus lactis.
It was expressed in terms of the activity of pure nisin manufactured by Rett.

Further, for solid products, it is possible to effectively suppress the growth of harmful bacteria by applying an appropriate amount on the surface.

The present invention is effective for soup powder, soup, canned beverages, and prepared foods such as potato salad, but it is not limited to these and can be used for all foods, and particularly foods containing starch. It has an excellent effect on heat-resistant spore-forming bacteria, such as heat-resistant flat sour bacteria, which easily occur.

[0018]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples.

Examples 1 to 4 and Comparative Examples 1 to 3 To the compositions shown in Table 1, distilled water was added to make 1 L, and the pH was adjusted to 6.5 ± 0.5. Streptococcus lactis IFO12007 cultivated in the same medium until the stationary phase (12 to 24 hours) was inoculated at 1% by weight.
Static culture was performed at 0 ° C. for 24 hours.

This culture solution was sterilized by heat treatment at 80 ° C. for 30 minutes, and then Micrococcus rutheus IFO333.
The bacteriostatic activity of the culture solution was measured by the plate diffusion method using 3 as the test bacteria. The activity was expressed in terms of the activity of the Nisin standard substance described above.

Further, a canned sashimi having the same formulation as that of Example 5 described later was mixed with 1% of each culture solution of Examples 1 to 4 and Comparative Examples 1 to 3 and drunk to 10 specialist panels. Table 1 also shows the results of evaluating the flavor.

[0022]

[Table 1]

Flavor Evaluation Criteria (10 panelists) ────────────────────────── Those who answered good and those who answered bad ────────────────────────── 8-10 people 0-2 people Good 6-7 people 3-4 people Good 3-5 people 5 ~ 7 people Somewhat bad 0-2 people 8-10 people bad ──────────────────────────

As shown in Table 1, when yeast extract or corn steep liquor was used as the nitrogen source (Examples 1 to 4), it was not used (Comparative Examples 1 to 3).
The activity was remarkably improved as compared with

The BHI medium (Comparative Example 1) and the polypeptone medium (Comparative Example 3) had remarkably poor flavor, and the medium (Comparative Example 2) in which skim milk was used in place of yeast extract and corn steep liquor gave a flavor. Not bad, but the activity was low.

Example 5 and Comparative Example 4 Using the bacteriostatic culture solution prepared in the same manner as in Examples 1 to 4, the canned sushi was prepared as follows according to the formulation shown in Table 2. The composition in the table represents% by weight.

Homogenization was carried out using a high-pressure homogenizer under the conditions of 65 ° C. and 150 kg / cm ² to prepare shiruko, which was filled in a can having a capacity of 200 ml. Furthermore, the number of spores is 10 ⁵ as the spore fluid of Clostridium thermoaseticum, which has spores that have been pre-activated on the spores in each can.
Add cans, tighten the cans and seal the cans at 125 ° C.
Sterilization was carried out by an autoclave for 20 minutes to produce a large number of canned sushi.

Here, the degree of vacuum in the can and the pH of the can contents of the cans sampled immediately after the heat sterilization treatment were measured, and the flavor of the can contents was examined in the same manner as in Examples 1 to 4.
Next, the remaining cans that have been subjected to the heat sterilization treatment are allowed to stand in an incubator at 55 ° C., the vacuum degree inside the cans and the pH of the cans content of the cans that have been sampled after 2 weeks and 4 weeks have elapsed are measured, and The flavor of the contents was also examined.

The results are shown in Tables 2 and 3. The method of measuring the degree of vacuum in the can is as follows.

A sample stored at 55 ° C. and stored was cooled to 20 ° C., and an in-can vacuum meter (apparatus used: vacuum can tester, manufactured by Japan Canning Association) was inserted into the can from the bottom of the can to measure the degree of vacuum. did.

The in-can vacuum gauge used has an atmospheric pressure of 0 and an absolute vacuum degree of 76 cmHg. Therefore, a larger value indicates a lower atmospheric pressure. That is, atmospheric pressure -18c
In this vacuum gauge, mHg is referred to as 18, and atmospheric pressure is -35 cm.
Since Hg is referred to as 35, the pressure of 35 having a larger numerical value is lower.

[0032]

[Table 2]

[0033]

[Table 3]

As compared with Comparative Example 4, in Example 5 of the present invention,
The flavor was good with no change. Further, when deterioration occurs, gas is generated from the contents, so that the pressure inside the can increases and the degree of vacuum decreases in Comparative Example 4, but in Example 5, vacuum occurs even after 4 weeks. I can't see any decline
It shows that it has not deteriorated at all.

[0035]

INDUSTRIAL APPLICABILITY The culture of the present invention can enhance the preservability of general foods without impairing the flavor of foods. In particular,
By exhibiting an effective bacteriostatic action against heat-resistant Clostridium thermoaseticum, foods containing the culture of the present invention, without the risk of spoilage by heat-resistant flat sour bacteria, usually By heat sterilization, it has good stability on storage with sufficient warming.

Claims (1)

[Claims] 1. A method for producing a bacteriostatic Streptococcus lactis culture, which comprises using a medium in which a nitrogen source consisting of corn steep liquor and / or yeast extract and a potato component are combined.