Effects of steaming cycles on the flavor profile, nutritional composition, chemical composition, and antioxidant activity of Citrus reticulata 'Dahongpao' Peel: A comparative analysis.

Steaming, a conventional processing technique, substantially affects the flavor and overall quality of peel of Citrus reticulata 'Dahongpao' (PCRD), a traditional medicinal and edible fruit peel. Changes in flavor and quality of PCRD induced by repeated steaming were examined by evaluating the effects of different steaming cycles on flavor-related metabolites, nutritional components (e.g., amino acids and total polysaccharides), bioactive constituents, and in vitro antioxidant activity. Metabolomic profiling and targeted chemical analyses were employed. A total of 403 aroma-related differential metabolites were identified in steamed PCRD, with the second steaming cycle representing a critical threshold for flavor compound alterations. Steaming markedly increased the concentrations of amino acids and total polysaccharides, while the second cycle specifically enhanced the levels of polymethoxyflavonoids, including tangeretin and nobiletin. Correlation analysis revealed marked associations between differential metabolites and the color parameters, flavor profiles, and antioxidant activity of PCRD. These findings provide insights into the mechanisms underlying quality enhancement in PCRD during traditional steaming and establish a scientific basis for optimizing processing techniques.