Comparison of three methods of preparing the powder form of yeast extract

Yeast extract obtained by hydrolysis of Saccharomyces cerevisiae as a baker yeast provides a high nutritional value for pharmaceuticals, food industries, microbial substrates, and biofuels. Two methods are typical to produce yeast extract, autolysis and hydrolysis. In this study, the rapid and cost-effective process of the hydrolysis method, including the mechanical methods of high temperature and pressure, was utilized to produce the yeast extract. The purpose of this study was to compare three methods, the Spray dryer, freeze dryer, and oven dryer methods, of preparing powder from bakery yeast extract. The effects of the produced yeast extracts were measured on gram-negative and gram-positive bacteria that were given as a bacteria feed to test the quality of products. The extract obtained from the freeze and spray dryer methods accelerated the growth rate of microorganisms. The bacteria Staphylococcus aureus and Escherichia coli showed better overall growth on the yeast extract attained from the spray dryer method. Hence, the produced spray dryer yeast extracts significantly improved the soluble expression and purification of the protein compared to the commercial extract. Results revealed that the spray dryer method preserves the properties of the yeast extract better than the other methods, and due to low moisture, this method can be used in industry. Nevertheless, all methods are applicable for yeast extract production.