Utilization of Candida utilis Cells for the Production of Yeast Extract: Effects of Enzyme Types, Dosages and Treatment Time

The purpose of this study was to establish an enzymatic hydrolysis process to prepare yeast extract with the advantages of low-cost and high-content of flavor nucleotides. Yeast extract was produced from the broken cell suspension of Candida utilis, using papain, 5′-Phosphodiesterase (RP-1) and Adenosine Monophosphate (AMP) deaminase. The effects of types, dosages and treatment time of enzymes on the recovery of solid, protein and flavor nucleotides, as well as the extract composition were investigated. Enzyme types remarkably affected the recovery of protein and solid and papain was found to be the most effective hydrolysis enzyme. The optimal dosage of papain and its treatment time were determined as 0.2% and 6 h, respectively. On this condition, the recovery of solid and protein of yeast cells was 69.26 and 60.87%, respectively. Further treatments with RP-1 (0.045%, 3 h) and AMPdeaminase (0.045%, 2 h) were employed to obtain a higher content of flavor 5′-nucleotides (GMP + IMP, 4.39%). This process had the advantages of a small amount of enzymes dosage, short enzymatic reaction time and high extraction yield.