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Updated: Jul 5, 2025
08:46
Analysis and Specification of Starch Granule Size Distributions
Published on: March 4, 2021
5.2K
Shochu Koji Microstructure and Starch Structure during Preparation
Tiantian Wang1, Isao Hanashiro2,3, Yumiko Yoshizaki1,2
11 Education and Research Center for Fermentation studies, Faculty of Agriculture, Kagoshima University.
Journal of Applied Glycoscience
|January 19, 2024
Summary
This study reveals how shochu koji mold enzymes break down starch, creating a spongy microstructure. Understanding these starch decomposition schemes and enzyme actions is key to improving shochu production.
Area of Science:
- Food Science
- Biochemistry
- Microbiology
Background:
- Shochu koji preparation involves complex biochemical transformations of starch.
- Understanding the enzymatic degradation of starch and its impact on koji microstructure is crucial for optimizing shochu quality.
Purpose of the Study:
- To investigate the changes in composition, microstructure, and starch molecular structure during shochu koji preparation.
- To elucidate the roles of different alpha-amylases and saccharification enzymes in starch decomposition and microstructure formation.
Main Methods:
- Analysis of shochu koji composition and microstructure at different preparation stages.
- Characterization of starch molecular structure changes using techniques like degree of polymerization (DP) analysis.
- Enzyme activity assays for acid-labile and acid-stable alpha-amylases.
Main Results:
- Starch granules were preferentially decomposed in their gelatinized and outer regions.
- A spongy microstructure developed as gaps between starch granules increased.
- Two types of alpha-amylases were produced: acid-labile (early/middle stages) and acid-stable (middle/late stages).
- Reducing sugars, primarily glucose, increased significantly, indicating active starch hydrolysis.
- Specific alpha-glucan fragments were observed, showing degradation of amylopectin's long B chains.
Conclusions:
- Enzymes like acid-labile and acid-stable alpha-amylases, glucoamylase, and alpha-glucosidase act on amorphous starch regions.
- Cooperative enzyme action during koji preparation drives the formation of the characteristic spongy microstructure.
- This study provides the first detailed report on starch decomposition pathways and microstructure development in shochu koji.
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