Recently, Non-Saccharomyces yeasts have attracted attention for improving and differentiating wine quality. It has been reported that Hanseniaspora vineae produces a large amount of acetic acid esters such as 2-phenylethyl acetate and ethyl acetate to produce wines with a fruity aroma. The winemaking suitability of H. vineaeTW15 isolated from‘Yamasachi’grapes was tested and a winemaking test using‘Yamasachi’grapes was conducted to analyze the fermentation of the wine and evaluate the quality of the wine. H. vineaeTW15 was found to have high sulfite tolerance and high alcohol tolerance as well as the ability to adapt to winemaking. H. vineae TW15 had a slower fermentation rate than commercial dry yeast for wine, but improved the wine quality. The taste was highly rated for its weak sourness due to its low total acids and high pH. We assumed that the aroma was highly rated because it produced more isobutyl alcohol, isoamyl acetate, 2-phenylethyl alcohol, and 2-phenylethyl acetate.

Effects of exogenous peptidase addition on the concentration of pyroglutamyl（pGlu） peptides in sake and also on the taste characteristics of sake were investigated. The addition of peptidase agents involving high acid carboxypeptidase（ACP） activity to sake decreased bitter-tasting peptides and increased（pGlu） L-ethyl. The addition of a peptidase agent with high（pGlu） peptide ethyl ester forming activity but low ACP activity increased（pGlu） LF-ethyl and（pGlu） LFNP-ethyl in sake；however, it did not increase（pGlu） L-ethyl. These effects were also observed in a test of adding purified（pGlu） peptide ethyl ester forming enzyme. It was suggested that the increase of（pGlu） oligo peptide ethyl esters except（pGlu） L-ethyl yielded positive effects on the taste of sake. The addition of a peptidase agent with high（pGlu） peptide ethyl ester-forming activity but low ACP activity increased（pGlu） oligo peptide ethyl esters in the digestion solution of the rice protein body（PB） by rice koji enzymes, but it did not increase（pGlu） L-ethyl. Addition of the peptidase to the sake mash caused similar effects as the addition to the PB digestion solution, but the effects were quite weak.

Two pyroglutamyl（pGlu）peptide ethyl ester forming activities in rice koji samples made by twelve commercial koji starters and Aspergillus oryzae RIB128 were analyzed. The（pGlu）LFGP-ethyl forming activity, type（A）activity, was found only in the rice koji made by a so-called “high glucoamylase starter” and RIB128, while the（pGlu）LFGPNVNPW-ethyl forming activity, type（B）activity, was found in all koji samples. The type（A）activity in koji samples showed a close relationship（R²＝0.90）between glucose forming activity, while the type（B）activity did not show this relationship.