Ken-ichi Otsuka

Phenolic Compounds in the Fermented Products:Part I. Origin of Ferulic Acid in Saké

The origin of ferulic acid in sake which is known as a source of many important flavor compounds in fermented products was investigated.Three forms of ferulic acid and sinapic acid were isolated from rice grains; i.e., free, lipid-bound and sugar-amino acid bound forms. The latter 2 forms were decomposed by Aspergillus oryzae to form ferulic acid and sinapic acid, a part of which was consumed by fungi and yeasts during koji making and fermentation. These microbes have no ability of methylation of caffeic acid to form ferulic acid.One of the bound forms of ferulic acid with sugar and amino acid consisted of 2 ferulic acid, 3 glucose, 1 glutamic acid and 2 calcium.

A Fundamental Study on the Semi-continuous Wine Making

甲州種ブドウ果汁を用いて, 三槽式回分法により半連続醸造を検討した。各槽の液量8l, 4l/day, 平均滞留時間2日, 醗酵温度20℃, 初発果汁糖濃度21%, SO250PPmの条件で, 2週間の経過では安定した醗酵が示された。一方, 上田氏の連続化の図式解法を用いて検討した所, 実験値とよく一致したので, 連続化の可能性を認めた。

Studies on the Fermentation Control of Sake Mash

協会7号, 泡なし酵母をもちいた高温糖化液の発酵における各種香気成分の挙動と, それらの生成における発酵温度 (15, 20, 25℃) の影響について検討した。1. 発酵温度が高くなる程生成されたEtOHに対する香気成分の生成量 (R) はi-BuOH, i-AmOH, Et. laurate, Phenethyl acetateでは増加し, Acetoin, Diacetyl, i-Amylacetateでは減少する。n-PrOH, n-BuOH, Et. lactate, Phenethyl alcohol, Et. caprateは発酵温度によってほとんど影響をうけない。2. Et. caprate, Phenethylacetate, i-Amyl acetate, Acetoin, Diacetylはアルコール発酵が進行中増加し, 次に滅少する。またPhenethyl alcohol, Et. laurateは発酵中増加し, 次に発酵末期か, 発酵終了後わずかに減少する。他方高級脂肪族アルコール, Et. lactateは発酵中増加する。3. 酵母別ではEthyl laurate, Phenethyl acetate, i-Amylacetateは7号酵母が泡なし酵母よりも生成大, 他方Acetoin, Diacetylは低温で, Et. lactateは高温で泡なし酵母が7号酵母よりも生成大である。

Studies on the Mechanism of Aging of Distilled Liquors: Part III. Comparison of Phenolic Compounds among Distilled Liquors of Differed Age

The Amount of ethyl acetate-extractable phenolic compounds in brandies or whiskies of differed aging grade was determined. Extractable phenolic compounds under neutral condition were increased along with proceeding of aging process.In comparison of chromatographic pattern obtained using silicic acid column, the first fraction from neutral extract was increased with aging. The fraction had a specific aroma.

Studies on the Mechanism of Aging of Distilled Liquors:Part I. On Phenolic Compounds from Oak Wooden Chips

Since the aging process of distilled liquors is regarded as the result of extraction of phenolic components from wooden barrel, the authors carried out the fractionation of the alcohol extract of oak wooden chips and examined the effect of the resultant fraction on whisky or brandy.A top fraction which was obtained by means of the method of silicic acid column chromatography developed a similar flavor to the aging flavor of distilled liquors when it was warmed with raw distilled liquor. The fraction contained phenolic components such as syringic and vanillic acidlike substances and unknown polyphenolic compounds. The authors suggested that these substances in the top fraction are concerned with the development of aging flavor. On the other hand, gallic acid was found from the other fraction.

Effect of Detergent on Wine Making

The authors determined the composition of musts and wines made from grape-clusters which were washed with a detergent (alkyl benzenesulfonate) (D).Both of the number of micro-organisms (wild yeast) and the amount of copper contained in musts (D) decreased in comparison with those made from clusters not treated with the detergent (C) and water-washed ones (W). Total acid and volatile acid in the wine of D was less than in the musts of C and W. Also, the content of tannin and color substances and iron in the wine of D was less than C and W.The sensory examination indicated that the quality of the wine treated with the detergent was clean. It may be due to the removement of wild micro-organisms and metal compounds such as copper and iron on the skin of grape berries.