Effects of Matrix Forms on Myofibrillar Protein Digestion across In Vitro and In Vivo Perspective: Hydrolysis Kinetics and Gastric Emptying

Abstract Dysphagia-adapted fluidized meat products alter the protein matrix structure and may impair digestibility. This work evaluated the digestive and nutritional properties of carboxymethyl cellulose (CMC)-modified myofibrillar protein (MP) thickened fluids across three matrices: liquid solution (MP), semisolid state (MP/CMC), and solid gel (MPgel). In vitro digestion indicated all MP matrices exhibited lower digestibility under elderly digestive conditions than adult systems, especially during gastric stage. CMC promoted protein hydrolysis by enhancing the accessibility of MP to pepsin. Digestive kinetics implied that initial and maximal gastric digestion rates of MP/CMC for adults were 13.07- and 3.65-fold higher than those of liquid MP, while dense cross-linked networks reduced digestion extent and rates in MP gel. In vivo, CMC thickening slowed gastrointestinal transit of semisolid MP, sustaining abundant gastric peptides and maintaining high steady-state serum total amino acids in mice. This work provided fundamental insights into the digestive and nutritional characteristics of CMC-induced meat protein-based fluids.