RU2441910C1 - Streptococcus thermophilus strains used for fermented milk products preparation - Google Patents

Abstract

FIELD: biotechnology.

SUBSTANCE: invention refers to the area of biotechnology and dairy products industry. Streptococcus thermophilus strains shall be obtained from the surface of the plant called stone pink. The strain is deposited with the Russian National Collection of Industrial Microorganisms (RNCIM) at registration number RNCIM-B 10089. The strain shall be cultivated in culture medium of firm and liquid texture milk.

EFFECT: enhanced fermented milk products preparation- Mechnkov curdled milk and sour cream with 10% fat content - using lactic bacteria with high antagonistic activity.

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Description

The invention relates to biotechnology and the dairy industry and is a new strain of thermophilic streptococcus, intended for the production of dairy products and bacterial preparations.

Known strain of Streptococcus thermophilus VKPM B - 4463/27 (A.S. No. 1664838), which has increased resistance to growth inhibitors, the ability to stably form a viscous, milk clot, indestructible with stirring, good compatibility with other strains of lactobacilli and pronounced physiological and biochemical properties .

The disadvantage of this strain is low antibiotic activity against opportunistic and pathogenic microflora.

The closest analogue (prototype) is a bacterial strain Streptococcus thermophilus VKPM B-9587 (p. RU 2337953), was obtained without the use of mutagens and genetic manipulations, a bacterial strain that is resistant to a number of adverse factors that occur during the process of fermentation of milk.

The disadvantage of this strain is low antibiotic activity against opportunistic and pathogenic microflora.

The objective of the invention is the creation of a dairy product using lactobacilli on accessible nutrient media with high antagonistic activity.

The problem is solved by using nutrient media of dense and liquid consistency:

sterile skim milk

hydrolyzed milk (pH 6.8-7.0).

The local strain of Streptococcus thermophilus was isolated under natural conditions of North Ossetia-Alania from the surface of the plant - clove sand.

The identification of the strain was carried out according to the method of L.A. Bannikova (1975) and deposited in VKPM under the number - B 10089.

The strain is deposited in the All-Russian collection of industrial microorganisms and has a number VKPM B-10089.

The strain of Streptococcus thermophilus VKPM B-10089 has the following characteristics:

1. Cultural and morphological:

- optional anaerobic;

- gram-positive cocci;

- 0.8 ± 0.03 μm;

- motionless;

- located in chains;

- do not form endospores.

On the surface of the agar medium (hydrolyzed milk) after 24 hours at a temperature of 37-42 ° C form:

- round colonies,

- size 1-2 mm (small);

- the nature of the contour of the edge is even;

- the relief is flat;

- surface - smooth, shiny;

- White colour;

- structure - granular;

- pasty consistency.

The study of the cultural or morphological properties of the selected strain of lactic acid microorganisms was carried out on a dense nutrient medium - agarized milk.

2. Physiological and biochemical:

- milk clotting speed - 6 hours at a temperature of 38-40 ° C;

- ultimate acid-forming ability in milk - 120 ° T;

- the strain ferments glucose, galactose, lactose, sucrose, arabinose, xylose, starch;

- grows at a temperature of 40 ° C, 45 ° C;

- grows in hydrolyzed milk containing 2% NaCl;

- grows in hydrolyzed milk containing 20% bile;

- marked growth in milk containing 0.01% methylene blue;

- withstands heating for 30 minutes at a temperature of 55 ° C and 60 ° C.

3. Antibiotic activity:

- the diameter of the zone of inhibition of growth in relation to the representative of the pathogenic microflora Staphylococcus aureus was 23 mm;

- the diameter of the zone of growth inhibition in relation to the representative of opportunistic microflora of Escherichia coli was 17 mm.

Determination of the antibiotic activity of the Streptococcus thermophilus strain VKPM B 10089 was carried out on solid nutrient medium (MPA) by agar diffusion.

The proposed new strain isolated from the surface of the plant carnation is sandy, well adapted to local conditions, easy to cultivate and store. In addition, the strain has high productivity and atibiotic activity in relation to opportunistic and pathogenic microflora.

Due to its pronounced biological and antibiotic properties (the ability to form a viscous milk clot, the diameter of the zone of inhibition of growth of Staphylococcus aureus is 23 mm, Escherichia coli is 17 mm), the strain is of industrial value for the dairy industry.

Example 1. Preparation of yogurt in Mechnikovskoy tank method using bacterial starter culture, which includes the proposed strain of Streptococcus thermophilus VKPM B-10089

To prepare a laboratory starter culture in 100 ml of sterilized skim milk at 43 ° C make one portion of the starter culture, consisting of S.thermophilus VKPM B-10089 and L.bulgaricus. Fermented milk is kept at the indicated temperature for 5-7 hours until a clot forms.

Production ferment is prepared by adding 100 ml of laboratory ferment in 10 liters of sterilized skim milk. Fermented milk is kept at 42-43 ° C for 5-6 hours until a clot forms.

Manufacturing sourdough is characterized by a clean, sour-milk taste, a uniform viscous consistency, titratable sourdough acidity of 85 ° T, micropreparations of cocci chain and single sticks.

For the preparation of yogurt, Mechnikovskaya, 3-5% of the production yeast is added to the prepared milk. The ripening process takes place at 42-43 ° C for 5-6 hours until a dense clot forms. The resulting product is mixed and served on bottling.

Example 2. The preparation of sour cream 10% fat

Sourdough has the following composition S.lactis, S. cremoris, S.diacetilactis and S.thermophilus VKPM B-10089 in a ratio of 1: 1: 1: 1. Fat cream is normalized to 10%, pasteurized at 87 ° C for 10 minutes, cooled to 30 ° C and 5% of the leaven of the above composition is added. Fermented cream is thoroughly mixed and fermented at 30 ° C until a strong clot forms and an increase in acidity of 75 ° T. The product is mixed, packaged and cooled. The consistency of the finished product is homogeneous, slightly viscous, the taste is pure sour-milk.

Claims (1)

Strain Streptococcus thermophilus VKPM - B 10089, used for the preparation of dairy products.