8589356421

Z.Konarbayeva. A.Saparbekova. L.Mamayeva. SELECTION OF STARTER CULTURES FOR THE MILK-GRAIN FRODUCTION

MATERIALS AND METHODS

The object of research were lactic acid bacteria, obtained firom lactic acid products and other substrates from various areas of South Kazakhstan Region:    cities    - Shymkent,

Turkestan, Kentau, Zhetysai, villages - Akbulak, Karasu, Martobe, Sairam, Koksayek, Chubar, Kazygurt, Tassay, Kershetas, Azatlyk.

A number of media is recommended for obtaining lactic acid bacteria from various sources. They are liquid and agarized media, their composition includes ingredients enriched in amino acids and vitamins, yeastrel and autolysate, protein hydrolysates. Extraction of highly active strains of microorganism from raw milk and sour milk products, plant raw materiał processed in South Kazakhstan Region, will allow obtaining starter cultures with necessary properties. Highly active strains of microorganisms will be used in the combination for making starter cultures for manufacture due to it needs to check up their symbiotic combination.

The process of extraction of lactic acid bacteria included several stages: selection of local milk raw materiał, containing lactic acid bacteria; seeding of the enriched culture on a dense nutrient medium and thermostating of inoculations; further separation of colonies into sterile nonfat milk and research of obtained strains according to the number of features; identification of their belonging to a definite class of lactic bacteria; the closing stage is the determination of their production value. At the selection of the researched cultures preference was given to those cultures that had sufficient high activity of milk ripening, average acid forming ability, considerable antagonist activity, antibiotic resistance. Obtained from various sources strains of lactic acid bacteria were subjected to microscopy, their activity of milk coagulation and organoleptic indicators were studied. In view of the necessity to get products of a viscous, creamy consistency preference was givcn to the strains, capable to form such a type of ciot; at this the formed ciot must have a sufficiently high moisture retaining ability.

The moisture retaining ability of lactic acid cultures clots and starters were determined in the centrifuge at the separation factor 1000. 10 cm³ of the destroyed ciot were introduced into centrifugal plastic test tubę with capacity of 15 cm³ and were centrifuged at the set rotation frequency during 5 minutes. At the end of the centrifugation process the volume of extracted whey in the sample was measured by its decantation into a graduated glass centrifugal test tubę for 10 cm³ or a beaker. By the amount of obtained whey one judges about the water yielding capacity of clots. The results are expressed in a number of milliliters of the whey, obtained from 10 cm³ ot clots (cm³ / 10 cm³).

The proteolytic activity was determined by the quantative content of tyrosine in non casein whey. High activity was observed for cultures, where tyrosine accumulation was morę than 300 y/J0'³L., average was in the interval 200-300 y/lff³L, Iow - less than 200 y/l0^sL. Table 3 presents the obtained results of dctermining the aroma forming, proteolytic and lipolytic activity of the strains.

Acid accumulation ability is the main property of lactic acid bacteria and this property is used in manufacture. The estimation of acid forming activity of cultures was carried out by the Turner method, determining the titratable acidity in medium [9, 10].

RESULTS AND DISCUSSION

As the result of the performed work, twenty one strains of various lactic acid bacteria were received. The extractcd lactic acid bacteria were referred to the family Streptococcaceae and Lactobacillaceae. The studied cultural and morphologic features of the cells have gave the possibility to determine the generic belonging of the studied strains, 9 of 21 strains: SH-4, SN-1, Tr-4, SS-2, SSa-1, SPz-1, K-l, TU-5, Tuz-2 are representatives of S. lactis\ strains SL-12, SSp-3, K-3 have the generic belonging S. cremoris; strains IT-2,    Tr-3, SPa-1, Kz-4 - S.

thermophilus\ to L.acidophilus refer two representatives SHA-2, Tr-2; strains SPm-2 is a representative of L. bulgaricus and strains obtained from wheat grains, SPz-2 and Kz-2 are referred to L. plan ta rum.

After using products, containing antibiotically active microorganisms, they can suppress undesirable microflora of the intestinal tract through reproduction of living cells that work out antibiotic substances. That is why use of lactic acid bacteria with expressive antagonistic capacity in the manufacture of treatment-preventive purpose products has a practical necessity. Antibiotically active microorganisms developing at manufacture of acid milk products can suppress the undesirable microflora and accumulate antibiotic substances in them. In Table 1 presented studies of antagonistic activity of LAB.

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Journal oflndustrial Technology and Engineering, 2012, 2(3): 29 - 36