Rind-core microbial niche differentiation at centimeter-scale modulates the sensory quality of solid-state...

Area of Science:

• Food Microbiology
• Fermentation Science
• Biotechnology

Background:

• High-temperature Daqu (HTD) is crucial for Moutai-flavor Baijiu production, supplying enzymes and flavor precursors.
• Solid-state fermentation of HTD leads to spatial heterogeneity due to mass and heat transfer limitations.
• The impact of this micro-environmental differentiation on HTD quality is not well understood.

Purpose of the Study:

• To investigate the relationship between spatial heterogeneity in HTD and its final quality.
• To characterize physicochemical properties and microbial succession at a centimeter scale within HTD.
• To identify key factors driving quality differences in HTD.

Main Methods:

• Analysis of 134 samples from 12 production batches of HTD.
• Centimeter-scale characterization of physicochemical properties (acidity, water content) and microbial communities.
• Microbial succession analysis using redundancy analysis (RDA) and laboratory validation.

Main Results:

• Whole-sample analysis did not differentiate high-quality from ordinary-quality HTD.
• Ordinary-quality HTD rind exhibited lower acidity than high-quality HTD rind in early fermentation (days 9-12).
• Significant microbial differentiation between rind and core was observed, with accelerated divergence in ordinary-quality samples, driven by acidity and water content gradients.

Conclusions:

• Centimeter-scale microbial heterogeneity is critical for HTD quality assessment.
• Spatial variations in acidity and water content drive micro-ecological differences.
• Understanding these micro-ecological dynamics provides insights into HTD fermentation and quality control.