Effect of fresh pepper at different ripening stages on the physiochemical quality and flavor of fermented Chinese pepper

Traditional Chinese fermented chili peppers possess a distinctive flavor. To determine the most suitable pepper raw material maturity for fermenting pepper, four maturity stages were selected: Green Ripening Stage, Color Turning Stage I, Color Turning Stage II, and Red Ripening Stage. These stages were studied to investigate the effects of maturation on the tissue structure, physicochemical quality, and flavor of pepper and fermented pepper. The findings indicate that the levels of reducing sugar, amino nitrogen, and total acid in fresh chili peppers rose as the fruits matured, whereas the concentration of volatile compounds notably declined. After fermentation, the tissue of the pepper loosened and texture softened, while the content of volatile substances increased significantly. Multivariate data analysis reveals that esters, aldehydes, and terpenes are distinct volatile compounds that undergo significant changes during the ripening process of chili peppers and fermented chili peppers. In brief, maturation significantly influenced the physicochemical and flavor quality of both fresh and fermented pepper. Fresh pepper at the Color Turning Stage II (50 days after flowering) was found to be the most suitable for fermentation. During this period, the tissue state of fermented pepper was optimal, resulting in the highest sensory score, a Chroma of 22.87, and a volatile substance content of 20.22 mg/kg, which was notably higher than in the other three periods. This study offers guidance for selecting raw materials and ensuring quality control in food fermentation. •Fermentation enlarged the effect of ripening on the flavor of peppers.•The microstructure of fresh and fermented chili peppers was compared.•Maturity contributed significantly to determine fermented chili pepper quality.•44 volatile compounds were screened as distinct compounds in fermented peppers.•Fermented chili pepper at Color Turning Stage II exhibited the best quality.