In vivo digestion and absorption characteristics of surimi gels with different degrees of cross-linking induced by transglutaminase (TGase)

To investigate the effect of the degree of cross-linking on the nutritive values of surimi gels, an in vivo rat model was used to evaluate their digestion and absorption properties in the digestive tract and serum by analyzing digestion sites and digestive products (including peptides and amino acids). Then, a Caco-2 monolayer model was used to explore the transport mechanism of TGase-induced G-L isopeptides. The results showed that myosin heavy chain (MHC) was the predominant protein source of identified peptides in the gastric and intestinal digests, but was rarely found in the serum. With the increase in cross-linking degree, the hydrolysis of myosin head was facilitated, the likelihood of the presence of bioactive peptides in the digested material was enhanced as well. From the aspects of total amino acids, the cross-linking degree have no influence (p > 0.05) on the digestion and absorption properties. The G-L isopeptides were transported intact across intestinal epithelium via passive paracellular diffusion. This study contributes to understanding the effects of enzymatic cross-linking on the nutritional characteristics of food.