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

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.