Effects of polysaccharides on protein in vitro digestion and rheological properties under simulated elderly gastric conditions

Polysaccharide hydrocolloids are widely used in milk protein to improve swallowing safety in dysphagia, but their effects on gastric digestion require critical investigation. This study compared xanthan gum (XG; with excellent rheological properties but potential digestion-impairing effects) and Naematelia aurantialba polysaccharide (NAP; a potential thickening polysaccharide) for their effects on sodium caseinate (SC) and whey protein (WP) digestibility and gastric emptying. The experiments utilized both INFOGEST (static) and DHS-IV (dynamic) digestion models under simulated elderly conditions. Results demonstrated that the addition of XG hinders protein digestion and delays gastric emptying. Specifically, XG reduced free amino groups release by 20.26 ± 0.08 % (SC-XG) and 21.82 ± 0.04 % (WP-XG). The gastric half-emptying time was prolonged by 14.90 ± 1.07 min (SC-XG) and 15.26 ± 1.10 min (WP-XG). In contrast, NAP was found to promote gastric-phase protein digestion. This study provides novel insights for the design of dysphagia-friendly foods for elderly populations.