EFFECTS OF RIBONUCLEIC ACID REMOVAL METHODS ON COMPOSITION AND FUNCTIONAL PROPERTIES OF Candida utilis

Nucleic acids were removed from whole cells and homogenates of Candida utilis by alkaline hydrolysis, enzymatic methods and washing with buffer. True protein of 42% in whole cells became concentrated, ash and carbohydrate contents generally decreased and relative lipid content increased with processing suggesting coprecipitation of lipid‐rich membrane material with proteins. The RNA content was 8% in whole cells and 45–97% reductions in RNA were obtained by various methods. Dry weight recoveries ranged from 45–80%. Protein recoveries ranged from 67–98%. Very small changes in amino acid compositions resulted from the various RNA removal methods with 5% or less change in percentage of essential amino acids compared to whole cells. Lysine was 92% available in whole cells and yeast homogenate and in no case did available lysine drop below 88%. Functional properties of the dried preparations, including bulk density, color and taste, protein solubility, water and oil binding, viscosity and heat thickening, foaming capacity and foam stability, and emulsifying capacity, activity and stability were determined and comparative tests were made with functional ingredients from nonyeast sources. Several of the preparations possessed functional properties that were equal or superior to soy flour or whey concentrate.