Shochu koji microstructure and starch structure during preparation

In this study, we investigated the changes in composition-, microstructure-, and starch molecular structure of shochu koji during preparation. We observed that gelatinized outer part was decomposed priority early middle preparation stages. The gap between granules increased with delayed time. Finally, microstructure became spongy. Shochu mold produced two α-amylases different expression manners. Acid-labile α-amylase Acid-stable saccharification power were late Throughout preparation, reducing sugars content reached approximately 13%–20% total sugar content, glucose representing over 70% sugars. α-Glucan fragments C chains degree polymerization [DP] 4–73 stages (<23 h), indicating degradation amylopectin at long B chains. latter stage, amount DP 6–30 decreased, while longer (DP 30<) did not change. These results showed acid-labile α-amylase, acid-stable enzymes including glucoamylase α-glucosidase work preferentially on amorphous regions granules, cooperative action these contributes to formation microstructure. Our study is first report decomposition schemes forming process koji.