Production of peptides and amino acids from microbial biomass in food and feed industries: biotechnological aspects

Introduction. Microbial biomass is a popular source of food ingredients and feed additives. Its high use has made it focus of many relevant studies. Yeast and fungal biomasses proved to be useful substrates that improve the quality and biological value of functional products. They differ in the content and composition of proteins and polysaccharides. The present research dealt with the enzymatic decomposition of proteins found in a novel fungal and yeast biomass. The research objective was to describe the peptide and amino acid composition of their enzymatic hydrolysates. Study objects and methods. The research featured a new fungal and yeast biomass mix. Aspergillus oryzae is a mycelial fungus and a popular industrial producer of hydrolytic enzymes in food industry. As for the yeast, it was the Saccharomyces cerevisiae strain, which is often used in baking. Results and discussion. The total content of identified amino acids in the fungal and yeast biomass was 306.0 mg/g, which was 1.5 times higher than in the fungal biomass alone. The biomass mix demonstrated a higher biological value of proteins than the yeast biomass. A set of experiments made it possible to compile a scheme for the biocatalytic destruction of polymers in the fungal and yeast biomass under the effect of fungal intracellular and endogenous enzymes. The article also contains a thorough description of the obtained enzymatic hydrolysates with various fractional compositions of peptides and free amino acids. Peptides with the molecular weight in the range of up to 29.0 kDa decreased by 2.1 times after 5 h of hydrolysis and by 10.7 times after 18 h. The designed conditions doubled the release of amino acids and increased the content of low-molecular-weight peptides up to 75.3%. Conclusion. The research provided a new algorithm for the biocatalytic conversion of microbial biomass. Regulating the conditions of enzymatic hydrolysis made it possible to obtain enzymatic hydrolysates with a desired degree of protein degradation. They could serve as peptides and amino acids in functional food and feed products.