Search

Due to the increasing shortage of food protein in the world, the most effective and complete use of proteinaceous substrates is an urgent task. The most promising way to utilize secondary protein-containing raw materials is to increase its nutritional value through enzymatic hydrolysis. The use of protein hydrolysates obtained from protein-containing by-products has great potential in various areas of the food industry, as well as in the production of foods for medical and special dietary uses. The aim of the research was to propose optimal methods for processing protein substrates to obtain hydrolysates with desired properties, taking into account the characteristics of the main types of proteinaceous by-products and the specificity of proteases used. Material and methods . We used the data contained in PubMed, WoS, Scopus, and eLIBRARY.RU databases, which meet the requirements of scientific reliability and completeness. Results . Collagen-containing wastes from the meat, poultry and fish processing industries, whey, soy protein and gluten are the main types of protein-containing by-products successfully used to produce food and functional hydrolysates. The molecular structure, basic biological and physico-chemical properties of collagen, whey proteins, various protein fractions of wheat gluten and soy protein are described. The expediency of enzymatic treatment of protein-containing by-products using proteases is shown to reduce antigenicity and eliminate anti-nutritional properties, improve nutritional, functional, organoleptic and bioactive properties for subsequent use in food production, including those for medical and special dietary uses. Information is presented on the classification of proteolytic enzymes, their main properties, and the effectiveness of their use in the processing of various types of proteinaceous by-products. Conclusion . Based on the literature data analysis, the most promising methods for obtaining food protein hydrolysates from secondary protein-containing raw materials are proposed, including pretreatment of substrates and the selection of proteolytic enzymes with a certain specificity., Competing Interests: The authors declare no conflict of interest., (Copyright© GEOTAR-Media Publishing Group.)

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 cm 3 , 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/dm 3 . 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/dm 3 . 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., Competing Interests: The authors declare no overt and potential conflict of interest related to the publication of this article., (Copyright© GEOTAR-Media Publishing Group.)

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 β-glucanase - 300 units of β-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 β-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., (Copyright© GEOTAR-Media Publishing Group.)

Background, Aims and Scope: Advances in radioecology can support improvements in environmental remediation technologies, especially by illuminating interaction processes between polymorphic metal radionuclides and various materials and their ions in aqueous solutions. This study modeled interaction processes of 90Sr with transitive metals to delineate the behavior of polymorphic metal radionuclides. Experimental and modeling results confirmed Sr sedimentation was sensitive to the physical impact of radionuclides on various sorbents and possible chemical reactions occurring between the radionuclides and sorbents., Methods: Models were developed to simulate 90Sr sedimentation process, and the potential physical and chemical reactions accompanying the process. Models were verified, inorganic salts were used as sorbents to absorb metal cations, activity levels were recorded before and after mixing the inorganic salts while the efficiency of sedimentation using the heavy metals composites was quantified., Results and Discussion: This research demonstrates that the process of the sedimentation is complex and occurs in several stages. Micro-structural analysis shows that zones of interaction between the sorbent and source metal are formed during the irradiation of the target's metal surface. Electrical-microscopic analysis indicates that the composition of the formed zones of interaction of Ti (Sr) with target metals has various structures. Roentgenophase analysis indicates that the interaction of the ions of a precipitable source and a target occurs according to constitution diagrams of equilibrium systems. The results indicate that application of inorganic salts composites based on modeling increases the efficiency of the deactivation of aqueous solutions when compared to standard aluminum sulfate composite., Conclusions: Experimental and modeling results confirm 90Sr sedimentation is sensitive to the physical impact of radionuclides on various sorbents and possible chemical reactions occurring between the radionuclides and sorbents. The models support estimation of the physical impact of polymorphic metal radionuclides on various components of sorbents and possible chemical reactions occurring between the radionuclides and sorbents during the interaction. Inorganic salt composites deactivate and clear 90Sr and Sr+2 from water.