The differences in main components, enzyme activity, and microbial composition between substandard and normal jiuyao

Area of Science:

• Food Science
• Microbiology
• Biochemistry

Background:

• Jiuyao is crucial for traditional huangjiu brewing, directly impacting final product quality.
• Assessing jiuyao quality is vital for consistent huangjiu production.
• Substandard jiuyao can arise from various factors affecting its composition and microbial profile.

Purpose of the Study:

• To differentiate between normal and two types of substandard jiuyao.
• To compare key components, enzymatic activity, volatile compounds, and microbial communities.
• To establish quality control markers for jiuyao.

Main Methods:

• Comparative analysis of chemical composition (water, starch, protein, amino acids).
• Enzymatic activity assays (protease, esterification, liquefaction, glycation).
• Gas chromatography-mass spectrometry (GC-MS) for volatile compounds and microbial community analysis (16S rRNA sequencing).

Main Results:

• Type I substandard jiuyao showed lower water, starch, acid protease, and esterification, but higher protein, liquefaction, glycation, and neutral protease.
• Type II substandard jiuyao exhibited lower overall indices, except for higher starch and free amino acids.
• 21 volatile compounds differed significantly; 2-pentylfuran identified as a substandard marker. Microbial analysis revealed distinct aerobic/anaerobic bacteria profiles for each type.

Conclusions:

• Water content significantly impacts jiuyao quality.
• Oxygen availability, influencing aerobic and anaerobic bacteria, is a key quality parameter.
• This study provides a foundation for jiuyao quality evaluation and control in huangjiu production.