Effect of mastication traits on carbohydrate degradation and gut microbiota composition during in vitro digestion and fermentation of citrus pulp

Mastication traits are key indicators for evaluating the texture of citrus fruits, influencing not only consumer sensory preferences but also the colonic fermentability of pulp fibers. This study investigated the carbohydrate degradation dynamics and microbial composition of Hongmeiren (HMR), Satsuma mandarin (WM), and Nanfeng tangerine (NF) with superior, moderate and inferior mastication traits, respectively, using oral chewing, simulated gastrointestinal digestion and colonic fermentation. Results showed that the segment membrane cells of HMR were loosely arranged and formed swallowable boluses after minimal chewing (7 chews), whereas NF required 25, exhibiting a 5.8-fold higher bolus hardness than HMR. Carbohydrates in citrus boluses underwent limited digestion in the upper gastrointestinal tract but were extensively fermented in the colon. HMR, being rich in pectin, exhibited higher fermentation rates, SCFA production, and a greater degree of carbohydrate degradation than WM and NF. Moreover, all citrus samples promoted probiotic enrichment and inhibited pathogens. These findings reveal that mastication traits influence citrus fermentation patterns and prebiotic potential, providing a scientific basis for citrus fruit breeding strategies.