Abstract: The effects of pH value, RNase from malted barley roots and the added proteinase on the yeast autolysis wereresearched. The results showed that: (1) 5’-nucleotide contents in yeast autolysate was slightly increased by adding RNase frommalted barley roots; (2) higher pH did not improve the 5’-nucleotide contents even in the presence of RNase from malted barleyroots, but at the pH 8.0, the addition of Acalase could increase the final yield, soluble protein contents and 5’-nucleotide inthe presence of RNase from malted barley roots. These results suggested that the reason for the low content of flavor enhancer( 5’-GMP) in the yeast extract may be due to the yeast cell wall that block the degradation of the adding RNase from maltedbarley roots on the RNA.

Key words: yeast extract, autolysis, flavor enhancer