Effect of dense phase carbon dioxide on the digestive properties of shrimp surimi gels: Insight from digestive kinetic.

Understanding the protein digestion rate and the release of nutrients in the gastrointestinal tract is critical to designing novel food products with enhanced functionalities. The digestion characteristics of untreated shrimp surimi and surimi gels induced by water-bath heating (WB) and different dense phase carbon dioxide (DPCD) treatment (L, M, and H crosslink degree) groups were studied. With the increasing crosslink, the protein digestibility increased and the average particle size decreased. The DPCD treatment condition (25 MPa, 50 °C, 60 min) induced H crosslink showed higher digestibility (91.31 %), compared to those other groups (P < 0.05). An increase in fluorescence intensity with redshift was shown in the gastric phase, while a decrease in fluorescent intensity with blueshift was displayed in the gastrointestinal phase. The MHC and actin bands were progressively degraded and disappeared with increasing digestion, and the intensity of low molecular weight < 10 kDa became obvious in late digestion. According to the digestive kinetic results, the H group showed that free amino acids decreased (325.77 ± 1.58 μmol/L) and then increased (789.18 ± 8.13 μmol/L) in the gastric phase, reaching a maximum value (5.86 ± 0.034 mmol/L) at the end of GI digestion phase (P < 0.05). The results suggested that the proper crosslink structure would provide a sustainable release of the nutritional value of shrimp surimi gels. This study provides the underlying mechanisms of surimi protein digestion and nutrient release in the GI tract.