[Promising races of baker's yeast for the production of food ingredients enriched with selenium and chromium].

It is known, that Saccharomycetes can accumulate mineral substances with targeted enrichment of the growth medium. However, the influence of the genetic affiliation of the culture and the technological factors of yeast strains, the composition of growth media on the efficiency of essential trace elements incorporation into the biomass and on the change of theirs intracellular components content have hardly been investigated. In this regard, the aims of this work was to select promising races of yeast Saccharomyces cerevisiae, develop a biotechnological method for obtaining food ingredients enriched with selenium and chromium on their basis, and study their trace element composition. Material and methods. Industrial strains of baker's yeast (Saccharomyces cerevisiae) were used: RCAM 01137, Y-3439 and Y-581. Yeast were grown on malt wort (pH 4.6) with a dry matter content of 12% with the addition of mineral salts in stationary conditions at a temperature of 30 °C for 18 h, after which the yeast biomass was separated by centrifugation. A method for enriching yeast with trace elements has been selected, which consists in the process of culturing cells on malt growth media containing chromium chloride or selenium dioxide in various concentrations. The total protein content was determined by the Kjeldahl method, polysaccharides and ergosterol - by spectrofluorometric method, selenium - by fluorimetric method. The content of trace elements in yeast biomass enriched with chromium was studied by mass spectrometric method with inductively coupled plasma. Results. It was shown that the highest specific growth rate was demonstrated by the yeast strains RCAM 01137 and Y-3439, and the highest level of maltase activity was in the Y-581 strain. It was found that the amount of biomass after cultivation of the yeast S. cerevisiae RCAM 01137 and Y-3439 was 6.00 и 5.42 g/100 cm3, respectively. It was noted, that the yeast S. cerevisiae Y-581 had capability of high synthesis of ergosterol (1.08±0.04%), the level of which was 2 fold higher than other strains. S. cerevisiae RCAM 01137 yeast showed the greatest ability to selenium enrichment, its content in biomass increased 137 fold and amounted to 2740 µg% when cultivated on a medium containing 800 µg/dm3. S. cerevisiae Y-581 yeast strain showed the highest capability to chromium sorption. The chromium concentration in its biomass was 8340 µg% in case of cultivating on a medium containing 750 µg/dm3. The usage of about 2.7 g of selenium enriched yeast biomass, or 1.0 g chromium enriched one, satisfies the daily requirement for these trace elements. Conclusion. Cultivation of S. cerevisiae cells on growth media containing trace elements makes it possible to obtain yeast biomass samples that can be used to obtain food ingredients for creating food products that contribute to the maintaining human health and improve the quality and duration of life.

[Biodegradation of proteins of grain raw materials for the production of new bakery products].

The effect of enzyme systems on the degree of protein destruction of grain crops to obtain new types of bakery products has been studied. Protein and amino acid composition of triticale grain crop in comparison with wheat and rye one has been studied. The high biological value of triticale proteins containing 38.75% of essential amino acids while in wheat - 34.93% has been shown. The influence of different enzyme systems (ES) with proteolytic action on the efficiency of catalytic modification of triticale proteins has been investigated. It was found that the highest activity was shown by the enzymatic system ES-1, synthesized by the mycelial fungus Aspergillus oryzae, as a result of which at a concentration of 5 u/g, the level of accumulation of amine nitrogen in triticale enzymatic hydrolysates was 125 mg%; the degree of hydrolysis of proteins was 90%. Enzyme preparations of bacterial origin, as well as alkalase and papain had a lower ability to hydrolyze triticale proteins. The fractional composition of modified proteins obtained by ES-1 showed a decrease in their molecular weight (to 35 kDa). Analysis of amino acid composition in grain enzymatic hydrolysates showed that as a result of exposure to FS-1, about 50% of the total number of amino acids passed into the free state, of which 38.8 to 43.6% were essential amino acids. The recipes of breads, containing composition of wheat flour and fermentolizates of the whole-grain triticale flour in the ratio 1:1 have been tested. The amino acid composition of the bread showed that the test samples contained 6.2 fold more free amino acids than the control. The use of fermented triticale in the recipes of bread allowed to increase the content of essential amino acids such as methionine, valine, isoleucine, leucine, phenylalanine, threonine, tryptophan and lysine in 2.0-5.0 times. It was shown that the developed technology allowed baking bread containing peptides with reduced molecular weight and free amino acids, which by its organoleptic and physic-chemical parameters corresponded to classic bakery products.

[The study of the process of enzymatic hydrolysis of yeast biomass to generate food ingredients with the specified fractional composition of protein substances].

With the use of enzyme systems (ES) the directed biocatalytic destruction of subcellular structures of the yeast biomass Saccharomyces cerevisiaе has been conducted for obtaining products of the specified structural-fractional composition. The composition of ES-1 included the enzymes catalyzing the hydrolysis of cell wall polysaccharides of yeast. Enzymes were dosed out at the rate of ß-glucanase - 300 units of ß-GcS/g of yeast, mannanase - 28.9 units of MS/g of yeast. ES-2, along with the enzymatic composition of ES-1, also contained a proteolytic complex, which included enzymes of bacterial origin, which were neutral, serine and metal-depended proteases (in a dosage of 2 units of PS/g of yeast). ES-3 consisted of the enzymes with ß-glucanase, mannanase, proteolytic activities and was further reinforced by high dose of proteases of fungal origin (10 units PS/g of yeast) for the implementation of deep hydrolysis of protein substances of yeast cell protoplasm to low molecular weight peptides and free amino acids. The action of enzymatic systems with different substrate specificity on the degree of destruction of subcellular structures of yeast was illustrated by electron microscopy. The resulting degradation products had different fractional composition and structural features. The results showed that ЕS-1 treatment of yeast led to deformation of the cell walls, but did not affect the composition of the protein fractions, represented by peptides with different molecular weight (20-60 kDa) that were characteristic for the starting material. The use of ES-2 has provided a deeper degradation of the protein-polysaccharide matrix of the cell walls and partial hydrolysis of proteins with the formation of soluble protein components with molecular weight less than 14 kDa. ES-3 treatment of yeast cells allowed to obtain composition with predominant content (89%) of free amino acids and short peptides with molecular weight up to 300 Da. The efficacy of targeted destruction of subcellular structures of Saccharomyces cerevisiae with getting of fermentation biomass with the specified fractional composition of protein substances for the production of food ingredients with special functional effects has been shown.