糀のでんぷん分解酵素

　糀が持つアミラーゼは、デンプンをグルコース（ぶどう糖）に分解する酵素です。この酵素は米、麦などの穀類や芋類、豆類のデンプンを糖化し、自然な甘味を引き出します。この働きは甘酒やみりん、味噌、醤油、日本酒などの発酵食品で、旨味や風味を支える重要な役割を果たしています。
　アミラーゼが生成する糖分は、酵母や乳酸菌といった発酵微生物の栄養源となり、発酵を促進します。特に日本酒では、糖化とアルコール発酵が同時に進む「並行複発酵」（糖化と発酵を一体化した独特の製法）が可能になります。また、アミラーゼによる糖化は消化を助け、腸内環境を改善する効果もあります。
　糀の酵素は、温度50～60℃、pH中性～弱酸性の条件で活性が最大化し、食品の風味と栄養価を高めます。糀のアミラーゼは、日本の発酵食品文化を支える基盤として不可欠です。
次回は、糀のたんぱく質分解酵素「プロテアーゼ」の働きと、　旨味を引き出す力についてお話しします。

The amylase in koji is an enzyme that breaks down starch into glucose. This enzyme saccharifies starches found in grains such as rice and barley, as well as in tubers and legumes, drawing out their natural sweetness. Its function plays a crucial role in supporting the umami and flavor of fermented foods like amazake, mirin, miso, soy sauce, and sake.

The sugars produced by amylase serve as nutrients for fermentation microorganisms such as yeast and lactic acid bacteria, promoting fermentation. In particular, sake production benefits from a unique process called “simultaneous saccharification and fermentation,” in which saccharification and alcohol fermentation occur simultaneously. Additionally, the saccharification by amylase aids digestion and helps improve gut health.

The enzymes in koji work most effectively under conditions of 50–60°C and a neutral to slightly acidic pH, enhancing both the flavor and nutritional value of foods. Koji’s amylase is indispensable as a foundation of Japan’s fermented food culture.

In the next session, we will discuss the function of koji’s protease, a protein-degrading enzyme, and its ability to bring out umami flavors.