Integrative Analysis of Flavoromics and Physicochemical Indicators Reveals the Impact of Strong-Flavor Daqu Storage on Baijiu Quality

During storage, the quality evolution of strong-flavor baijiu daqu fundamentally shapes the flavor framework of the base baijiu. However, the mechanisms by which daqu storage affects the subsequent fermentation quality remain unclear. To address this, this study integrates physicochemical analysis, flavoromics, and statistical modeling to elucidate the transmission of flavor quality in strong-flavor baijiu. Results showed that during a 1-to-6-month static storage period, the enzymatic activities of daqu (liquefaction, saccharification, and ethanol fermentation capacity) declined. Despite this enzymatic decline, the subsequent solid-state fermentation resulted in flavor enrichment: 17 key esters increased 2- to 3-fold, total esters increased by 35%, and total acidity was regulated to 2.69 g/L. Statistical modeling further revealed that this flavor variation was driven by selective regulatory patterns: initial starch content and acidity were identified as the primary positive drivers for the accumulation of complex long-chain esters, whereas ammonium nitrogen and hydrolytic enzyme activities were more closely associated with the formation of short-chain esters. This research provides a scientific foundation for the baijiu industry to strategically manage daqu storage and optimize ester aroma profiles.