Effect of various seasonings on enzyme activity of raw soy sauce

<p>[Purpose] The raw soy sauce is not heated, so not only does it have a bright color and mild aroma, but it is also characterized by residual enzymes such as protein and starch degrading enzymes. Raw soy sauce is sometimes used by itself, but it is often combined with other seasonings, and depending on the kind of seasoning, the enzyme activity remaining in raw soy sauce may be affected by the seasoning. In this study, in order to clarify the cooking characteristics of raw soy sauce in cooking combined with other seasonings, the effects of various seasonings on various enzyme activities of soy sauce were examined in a model experimental system simulating actual cooking.</p><p>[Methods] The raw soy sauce used was Kikkoman koikuchi nama shoyu. Seasonings were caster sugar, mirin (mirin, mirin-like seasoning, and boiled-down mirin), cooking sake, and grain vinegar. The proportions of each seasoning were set at three levels based on the proportions generally used. The heating temperatures were 60℃ and 100℃, and the heating times were changed to 1 to 60 min. The protease activity (Folin colorimetric method) and α-amylase activity (α-amylase assay kit: α-amylase assay kit) under each condition were measured. (Kikkoman BioChemifa).</p><p>[Results] In the case of unheated, the enzyme activity decreased only in the combined use of grain vinegar. When heated at 60℃, the higher the combined ratio of caster sugar, mirin, mirin-like seasoning, and boiled-down mirin, the more various enzyme activities contained in raw soy sauce remained. From this result, it was considered that the carbohydrate compounds common in various seasonings protected various enzymes. When cooking which sufficiently utilizes the effect of enzymes contained in raw soy sauce is carried out, it is desirable to consider the amount of carbohydrate compounds contained in seasonings and ingredients used in combination, including heating temperature and time.</p>