Digestive Fate of a Seaweed-Yak Meat Protein–Polysaccharide Matrix under Simulated Elderly Gastrointestinal Dysfunction: Nutrient Release, Antioxidant Response, and Peptidomic Remodeling

Abstract Age-related gastrointestinal dysfunction may alter the digestive fate of composite foods. Using a static in vitro model, we compared a seaweed-yak meat matrix under four simulated older-adult gastrointestinal conditions: normal gastric and intestinal function, isolated intestinal dysfunction, isolated gastric dysfunction, and combined dysfunction. Intestinal digestion decreased particle size from 2325.03 nm to 731.74–1088.07 nm and significantly increased apparent protein digestibility from 9.72–29.05% to 73.27–83.73% (P < 0.05). Combined dysfunction significantly reduced terminal digestibility to 73.27% compared with 83.73% under normal conditions (P < 0.05) and retained larger, heterogeneous aggregates. Peptides of 801–1400 Da predominated (45.5–45.8%), while 18,499 of 19,681 peptides (94%) were shared among groups. Peptides uniquely assigned to yak proteins accounted for 97.039–97.466% of normalized precursor-ion abundance, whereas seaweed-only peptides accounted for 0.1078–0.1241%. Peptide clustering indicated abundance remodeling within a conserved, yak-dominated pool, with terminal profiles more strongly associated with gastric than isolated intestinal dysfunction.