Quality enhancement strategies for Chinese dark tea from three major production regions based on fermentation process parameter regulation

This study systematically optimized fermentation process parameters for China’s three major dark tea production regions and established a synergistic regulation model for quality enhancement. Single-factor experiments, orthogonal experiments, and response surface methodology were employed to investigate Anhua (Hunan), Chibi (Hubei), and Wuzhou (Guangxi) regions. Optimization effects were evaluated through sensory evaluation, physicochemical analysis, and correlation analysis. Results showed the optimal parameter combination for Anhua region was fermentation temperature of 55 °C and fermentation time of 20 days, achieving a sensory score of 91.2 points (highest among three regions), representing a 10.8% improvement over controls. Theaflavins showed highly significant positive correlation with sensory scores ( r = 0.83), while tea polyphenols exhibited significant negative correlation ( r = −0.66), establishing theaflavins as the core quality regulation factor. Under optimized conditions, theaflavin content increased by over 60% compared to traditional processes across all regions. Principal component analysis revealed the first two components explained 82.6% of total variance, with regions displaying gradient distribution in quality characteristics. Volatile compound analysis identified 45 compounds, with linalool showing strongest positive correlation with sensory scores ( r = 0.69). This synergistic optimization model provides scientific evidence for standardized production and industrial development of dark tea.