清酒の香気成分に関する研究(第9報)

Abstract

Previously, p-hydroxybenzaldehyde, p-hydroxybenzoic acid and its ester were separated and identified in Saké as new phenolic compounds, and it was considered to be produced by fermentation of L-tyrosine. For confirmation of this suggestion, the fermentation products were extracted with ether from 2l of Hayduck solution to which was added 2g of L-tyrosine in place of L-asparagine and left standing for 7 days at 28°C after adjusting to pH 4.0 and adding Saké yeast (Kyokai No. 7). Then, the extract was successively shaken with saturated solution of sodium bicarbonate, 10% aqueous solution of sodium carbonate and 5% solution of potassium hydroxide. Three phenolic acids were separated and identified from sodium bicarbonate solution, which were p-hydroxybenzoic acid, p-hydroxyphenylacetic acid and l-p-hydroxyphenyllactic acid. But, it was evidenced that p-hydroxyphenylacetic acid was produced by oxidation of p-hydroxyphenylacetaldehyde during the separating procedure. The weak acidic substance from 10% sodium carbonate solution was treated with 25% sodium bisulfite and weak acidic carbonyl compound was isolated. Then, it was identified with p-hydroxybenzaldehyde. The other phenolic compound from 5% solution of potassium hydroxide was agreed with tyrosol. On these results, it was cleared that p-hydroxybenzaldehyde and p-hydroxybenzoic acid, the new fermentation products from L-tyrosine, were produced in fermentation of L-tyrosine by yeast on the different metabolic path way from Ehrlich's mechanism.