Physicochemical Characteristics of High-Temperature Daqu with Different Colors and Their Influence on Fermentation Quality

Abstract

Aims: This study aimed to compare the physicochemical characteristics of white, black, and yellow high-temperature Daqu to determine how moisture, acidity, starch composition, amino acid nitrogen, saccharification power, and liquefaction activity relate to functional performance during Baijiu fermentation. Study Design:  This was an experimental, laboratory-based comparative analysis of three Daqu types differing in color and fermentation stage. Place and Duration of Study: The study was conducted 1College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, over a period of three months. Dec. 2024 to Feb. 2025. Methodology: White, black, and yellow Daqu samples were collected and analyzed for moisture content, total acidity, starch and amylose levels, amino acid nitrogen, saccharification power, and liquefaction activity. Standard physicochemical assays were applied, including oven‐drying for moisture, titration for acidity, colorimetric and enzymatic assays for starch composition and nitrogen content, and activity-based methods for quantifying saccharification and liquefaction capacity. Data were statistically compared across Daqu types to identify significant physicochemical differences. Results: Marked physicochemical variation was observed among the Daqu types. Black Daqu showed the highest moisture content, consistent with enhanced water absorption during storage, while yellow Daqu displayed the highest acidity, indicating more active biochemical and microbial metabolism. Starch, amylose, amino acid nitrogen, and liquefaction activity showed no significant differences across samples (P > 0.05), suggesting comparable substrate availability and baseline enzymatic potential. In contrast, saccharification power differed significantly (P < 0.05), with yellow Daqu presenting the lowest activity, implying reduced amylolytic capacity and potential effects on sugar release and fermentation kinetics. Conclusion: Daqu color is linked to different physicochemical characteristics that affect its fermentation performance. Moisture, acidity, and saccharification ability were the main factors distinguishing the Daqu types and shaping microbial activity and aroma development. These results can guide better Daqu selection for quality control and point to the need for combined microbial and metabolomic research to fully explain how Daqu influences Baijiu aroma and overall product quality.