Tamotsu Yokotsuka

Soy Sauce Biochemistry

Publisher Summary This chapter explains that there are major differences between the saccharification process in traditional food preparation of Western countries and that of the Orient. Shoyu is the Japanese name for soy sauce, a popular liquid condiment used in oriental cuisine. Many varieties of shoyu are produced in Japan and other oriental countries. Japanese-fermented shoyu of the koikuchi type involves five main processes—the treatment of raw materials, the making of koji, the making and aging of mash, pressing, and refining. Fifty years ago, only whole soybeans were used as the raw material for shoyu. The color and flavor of shoyu are very closely related, as both are affected by the aging of mash and the pasteurization of raw shoyu. The color of shoyu is an important attribute to Japanese dishes although it has become lighter in recent years. Using a multivariate analysis, Tanaka indicated that among the factors by which preference for a given shoyu was formed, its chemical composition as a whole contributed only 46.3%. More than 20 Japanese investigators had isolated about 130 flavor compounds from fermented shoyu by the time Goto first introduced the gas chromatography mass spectrometry (GCMS) method into this area of research in 1973, adding six new volatile compounds using this method. The precise mixture of soybeans and wheat used as the raw materials in shoyu production is the result of technological know-how developed over hundreds of years.

Aroma and Flavor of Japanese Soy Sauce

Publisher Summary This chapter discusses the flavor substances of true Japanese soy sauce produced by the traditional fermentation method. The chemistry and composition of Japanese soy sauce has been reviewed, with emphasis on the flavor and aroma constituents. Over 90% of Japanese soy sauce is the koikuchi type, containing about equal amounts of fermented sauce and a chemical hydrolyzate, obtained from defatted soybeans. The volatile compounds in raw soy sauce and in soy cake are classified as: aliphatic carbonyl series; aliphatic esters, alcohols, and acids; sulfur-containing compounds; phenols; and other aromatic compounds. The specific aroma of soy sauce is due to sulfur-containing compounds. However, most of the aroma and flavor of soy sauce exists in the acid fraction. Tyrosol or p-hydroxyphenylethyl alcohol is found in commercial soy sauce and is associated with the bitterness of soy sauce. The characteristic flavor ingredients produced by cooking soy sauce are the guaiacyl compounds such as: vanillin, vanillic acid, ferulic acid and 4-ethylguaiacol. Among these, vanillin was the most aromatic. The factors related to the aroma and flavor of soy sauce that have been discussed in this chapter include raw materials; condition of fermentation, especially the volume of salt water relative to koji, salt concentration and aging period; and microorganisms involved in digestion and fermentation.

Studies on the Polysaccharides from Soy Sauce Part I:Purification and Properties of Two Acidic Polysaccharides

Two water-soluble acidic polysaccharides were isolated and purified from soy sauce and their physico-chemical properties were investigated. The purified preparations seemed to be homogeneous on ultra-centrifugation and also on zone electrophoresis. Their sedimentation coefficients were 6.35S and 1.9S, and their intrinsic viscosities were 0.47 and 0.11 dl/g, respectively. Molecular weights were estimated to be 320,000 and 16,000 by gel filtration technique. Consequently, it was proved that these acidic polysaccharides were close in their sugar compositions to those prepared from soybean cell wall by the enzymatic decomposition. Therefore, these acidic polysaccharides in soy sauce were presumed to be originated from soybean cell wall

A Ribonuclease from Mung Bean Sprouts Part II

前報に引き続き,緑豆発芽体より分離精製したribonucleaseの性質について,とくに亜鉛イオンの影響に関して検討を行なった.本酵素の活性発現には金属が関与し,その金属を除去することによって酵素は不可逆的に失活したが,今回の実験によってはその金属を明らかにすることはできなかった.しかし,本酵素に対してZn++が各種の効果を示すことを認めた. (1)酸性に対する透析において, Zn++の存在は活性の低下をある程度防止した. (2) Zn++はpH安定性において酸性における安定性を高めた. (3)また,熱処理に対する安定性を増強させた. (4) Zn++を添加することによって,安定性に対する最適pHがアルカリ側から酸性側に移動した. (5) Zn++は酵素活性,至適pH,至適温度および特異性には全く影響を示さなかった. (6)以上の効果はZn++に特異的で,他の金属イオンには認められなかった. (7)緑豆発芽体の酵素系のうち, RNaseにのみZn++の効果が認められ, phosphomonoesteraseおよびphosphodiesteraseには全く影響が見られなかった.

Studies on Utilization of Enzymes Produced by Actinomycetes. Part III

(1) 放線菌No.41菌株の培養液よりアルカリ性プロテアーゼの精製を行なった. (2) この酵素の至適作用pHは10.0で, pH5.0～9.0の範囲で安定である.また, 70°10分間で完全に失活する. (3) Potato inhibitor及びDFPにより阻害を受ける.金属イオンによる活性の促進は認められない.Cu++, Hg++により強く阻害される.

Studies on the Analytical Methods of Soy Sauce. Part III

(1) イオン交換樹脂を用いて糖そめ他の夾雑物を除き,糖の影響なくポリオールを直接定量する方法を得た. (2) 麹中のポリオールは麹によってその量が著しく異り,グリセリン以外のポリオールも多く存在する. (3) 醗酵旺盛な醤油諸味液汁中のポリオールはマンニトールとグリセリンである,両者の比は1:1ぐらいである. (4) よく熟成した諸味中のポリオールはほとんどグリセリンである.

Studies on the Analitical Methods of Soy Sauce

(1) 醤油中のグリゼリン定量に於て問題となる他物質殊にマンニトール(8)その他よりのグリラリンの分離に関し,各種沈澱剤による不純物の除去,各種溶剤によるグリセリンの抽出,過熱水蒸気によるグリセリンの水蒸気蒸溜,減圧水蒸気蒸溜等を検討し水を数回に分けて加えつつ行う減圧水蒸気蒸溜に依ってのみグリセリンを完全に而も定量的に分離する事が出来たので更にその方法を各種の条件に就いて検討し,殆んど100%の回収試験を行うことが出来た.次で分離した試料のグリセリンは過沃度酸酸化法によって,比色定量した. (2) 此の方法によれば丸大豆を原料とした醤油1ml中に10～12mg,脱脂大豆を用いたものに6～7mgのグリセリンがあり,この場合原料丸大豆中のグリセリンの計算値は約5mg/mlであるから醤油諸味中の醗酵に於てかなりの量のグリセリンが油脂の代謝以外から生成されている事が結論づけられる. 一方各種市販醤油のグリセリン定量値は銘柄により3～10mg/mlの大きな差が見られる(本内容は東京に於ける昭和32年2月23日農芸化学支部会にて報告した).