Temperature-Driven Divergence in Microbial Consortia and Physicochemical Functionality: A Comparative Study of High- and Medium-Temperature <i>Daqu</i>
<i>Daqu</i>, a crucial fermentation starter for Chinese <i>Baijiu</i>, develops distinct microbial and physicochemical profiles depending on fermentation temperature, which significantly influence enzymatic activity and flavor formation. While high-temperature (HT-<i>Da...
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| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Microorganisms |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-2607/13/6/1312 |
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| Summary: | <i>Daqu</i>, a crucial fermentation starter for Chinese <i>Baijiu</i>, develops distinct microbial and physicochemical profiles depending on fermentation temperature, which significantly influence enzymatic activity and flavor formation. While high-temperature (HT-<i>Daqu</i>, 65 °C) and medium-temperature (MT-<i>Daqu</i>, 60 °C) variants are known to produce different liquor aromas, systematic comparisons of their microbial and physicochemical dynamics remain limited. This study integrated physicochemical assays (moisture, starch, acidity, enzymatic activity) with 16S rRNA and ITS (Internal Transcribed Spacer) sequencing to analyze HT-<i>Daqu</i> (HQ1–HQ3) and MT-<i>Daqu</i> (MQ1–MQ3) from Sichuan breweries. Results revealed that HT-<i>Daqu</i> exhibited significantly lower moisture (<i>p</i> < 0.05) and starch content (<i>p</i> < 0.05) but higher acidity <i>(p</i> < 0.05) compared to MT-<i>Daqu</i>. Enzymatic activities were generally reduced in HT-<i>Daqu</i>, except for neutral protease. Microbial profiling revealed distinct microbial dynamics between HT-<i>Daqu</i> and MT-<i>Daqu</i>: HT-<i>Daqu</i> harbored thermophilic <i>Bacillus</i> (40–60% relative abundance) with reduced fungal diversity, while MT-<i>Daqu</i> prioritized fungal consortia—<i>Aspergillus</i> dominated MQ1 (78%) and <i>Saccharomyces</i> transiently peaked in MQ2 (35%)—which correlated with enhanced saccharification enzyme activities and esterification potential. Alpha-diversity indices confirmed higher bacterial diversity in HT-<i>Daqu</i> and greater fungal richness in MT-<i>Daqu</i>. Correlation networks highlighted temperature-driven linkages, such as <i>Bacillus</i> positively associating with acidity. These findings elucidate the trade-offs between microbial stress adaptation and metabolic efficiency under different thermal regimes, providing actionable insights for optimizing <i>Daqu</i> production through targeted microbial management and temperature control to enhance liquor quality. |
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| ISSN: | 2076-2607 |