To elucidate the regulatory mechanism of straw domestication on Jiang-flavor Daqu quality, this study systematically tracked variations in physicochemical properties and flavor compounds between Daqu fermented with aged versus fresh straw. Results showed that moisture content in aged-straw Daqu remained above 18.2% during the early fermentation stage (days 0–9), significantly higher than the fresh-straw group. This moisture retention was accompanied by thermodynamic differentiation: aged-straw Daqu exhibited a “delayed peak with gradual decline” pattern (peak temperature 46.8 °C on day 6, maintaining a high-temperature plateau from days 3 to 9), whereas fresh-straw Daqu followed an “early peak with rapid decline” trajectory (peaking at 50.7 °C on day 3 before deteriorating quickly). Total acidity was significantly elevated in the aged-straw group (1.9 vs. 1.0 mmol/10 g, p < 0.05). However, this acidic environment was associated with lower activities of starch-hydrolyzing enzymes, resulting in comparatively lower diastatic and liquefying powers. Flavor profiling identified 1539 volatile compounds. Redundancy analysis revealed moisture, temperature, and liquefying power as key driving factors, explaining 44.24% of variance (p = 0.002). Although the overall flavor architecture remained similar between groups, characteristic compounds differed markedly. Aged-straw Daqu was enriched with derivatives from Maillard reactions and lipid oxidation, contributing to a more substantial flavor foundation. In contrast, fresh-straw Daqu tended to accumulate primary alcohols and exogenous residues. Collectively, aged straw was associated with greater flavor complexity and typicality of Jiang-flavor Daqu, likely through optimization of microenvironmental homeostasis, without altering the fundamental flavor framework.
Wu et al. (2026) studied this question.