Structural characteristics and digestibility of bovine skin protein and corn starch extruded blend complexes

The interaction mechanism and digestibility of bovine skin protein (BSP)/corn starch (CS) blend complexes prepared by single screw extrusion were investigated. The effects of temperature and BSP/CS ratios on the physicochemical properties of BSP/CS blend complexes were analyzed. The results showed that the BSP/CS blend complexes extruded at a ratio of 3:7 had higher bulk density, texture and RVA viscosity compared with that of 7:3 and 5:5. It was mainly because the CS improved the formation of BSP/CS gel network structure through the screw extrusion. BSP and CS achieved an optimal entanglement at this ratio, potentially making pets play longer. The interaction between the -COOH of CS and the -NH3 of BSP during the process of extrusion was detected. The micrograph of blend system at ratio of 5:5 showed looser and special mosaic structure compared with other ratios, and further led to greater digestion rate. So we can design products with digestibility or longer play time by adjusting different proportions.