In the technologies of sour-milk production, the fermentsare used containing sour-milk streptococci, kefir fungi, bacillus bulgaricus, bifidobacteria and corresponding enzyme preparations. The ferments are not stable to the high temperatures, antibiotics and other denaturating factors. The decrease of enzymes and microorganisms activity results into deterioration of sour-milk products quality or into lack of ripening.

To increase the stability of ferments, it is to immobilize the microorganisms and enzymes. The use of gelatin and water-soluble starch as carriers (matrix), is not studied yet.

Gelatin is a powder without color and odor, it is used as thickening agent able to create gel structure. It is obtained by long boiling of collagen of skin, bones, cartilages and hooves. This processing enables hydrolyzation of some covalent ties of collagen.

The value of this carrier is its non-toxicity and light biodegradation, which allows using gelatin in pharmaceutic and food industries. The gelatin in the body of animal and human improves flow of amino acids and improves digestion in stomach and intestine.

The starch is a mixture of polysaccharides with amylose as the main component. On the basis of starch, the water-soluble carriers are obtained with different functional groups. These carriers are used in the medicine and food industry. Such a choice is due to the simple degradation of the carriers.

The aim of the study was to compare the gelatin and starch content as carriers for immobilization of ferments for sour-milk products and milk bacteria by investigating their sorption properties simulated by vitamin В₂.

The model research was carried out in laboratory conditions of the Research Institute of food technologies and animal processing technologies of Bila Tserkva national agrarian university.

For the experiment, the natural gelatin was used (quickly soluble for food purposes (P-11) produced according the State Standard 11293-89), soluble potato starchfor iodometry (С₆Н₁₀О₅) produced according the State Standard 10163-76 and 0.005 % solution of vitamin В₂.

Studying the sorption properties of gelatinin control variant, the latter was mixed with distilled water. The gelatin was mixed with 0.005 % solution of vitamin В₂. After 30 min the mixture was filtrated and in the filtrate the optical density was measured. The experiments with starch were carried out in the same way.

A common regularity was discovered, that the optical density of filtrate decreased if the gelatin mass in mixture increases. With the use of 1.0 g gelatin powder in the 25 cm³ of 0.005 % solution of vitamin B₂ (the experiment variant I), the value of D was by 2.0 times higher than the control one. Compared to the optical density of 0.005 % vitamin B₂ solution, the index of the experiment variant I was by 1.96 times lower (р<0.01).

With the use of 2.0 g gelatin, the optical density of filtrate in the experiment variant III decreased by 2.4 times compared to the 0.005 % solution of vitamin В₂ (р<0.001).

The least optical filtrate density was observed in the experiment variant IV. The index was by 3 times less compared to the D 0.005 % of vitamin B₂ solution.

It was also observed that the filtrate volume decreased with the increase of gelatin mass.

The use of the 1.0 g and 1.5 g water soluble starch (experiment variants I and II) did not impact the level of optical density compared to the D 0.005 % of vitamin B₂ solution.

In the experiment variant III the optical density decreased by 16.6 % (р<0.05). The optical density of the solution decreased when the starch was used in the amount of 2.5 g. The difference with the index D 0.005 % of the vitamin B₂ solution was 22.1 %.

Comparing the indexes of optical filtrate density of 0.005 % vitamin B₂ solution with gelatin content 1.5; 2.0 and 2.5 g and the indexes of optical filtrate density of 0.005 % vitamin B₂ solution with soluble starch solution content 1.5; 2.0 and
2.5 g, it was observed that the value of D, in case of gelatin application, was lower by 2.0; 2.04 and 2.44 times respectively.

Thus, it was established that gelatin has higher sorption abilities compared to soluble starch.

Key words: carrier’s capacity, sorption properties, carriers, immobilization, gelatin, starch, distilled water.