Effects of Pomelo Peel-Derived Dietary Fibers on Simulated Intestinal Digestion and Fermentation of Fish Balls In Vitro

The effects of pomelo peel-derived dietary fibers (total dietary fiber, cellulose, and microcrystalline cellulose) on <i>in vitro</i> simulated gastrointestinal digestion and fermentation characteristics of silver carp fish balls were systematically investigated. Our findings revealed that pomelo peel dietary fibers significantly enhanced protein digestibility (highest increased by 18.58%), free amino acid content (most elevated by 13.27%), and slow digestion starch content (highest increased by 64.97%) in fish balls, suggesting an improved nutritional quality of fish balls. Moreover, pomelo peel-derived dietary fibers increased the content of short-chain fatty acids in the digestive fish balls at the late stage of fermentation (48 h) and caused changes in gut microbiota with reducing the ratio of <i>Firmicutes</i> to <i>Bacteroidetes</i> (F/B), the abundance of <i>Escherichia-Shigella</i> and <i>Streptococcus</i>, and increasing the levels of probiotics <i>Bacteroides</i> and <i>Phascolarctobacterium</i>. These suggested that pomelo peel-derived dietary fibers could promote the digestive characteristics of fish balls, effectively exerting prebiotic effects by regulating gut microbiota. The results could provide a scientific basis for the enhanced modification of intestinal digestion and fermentation of fish balls with dietary fibers.