Hygroscopicity and antioxidant activity of whey protein hydrolysate and its ability to improve the water holding capacity of pork patties during freeze-thaw cycles

The antioxidant capacity and hygroscopic properties of whey protein hydrolysates and their ability to improve the water holding capacity of pork patties during repeated freeze-thaw cycles (F-T cycles) were investigated in this study. It was found that the optimum hydrolysis time of native whey protein (NWP) was 4 h by hydrolysis degree and iron reduction antioxidant capacity. The separation of 4-h hydrolysate by molecular weight showed that fraction I (F I < 1 kDa) was the most important antioxidant component. Furthermore, it was found that F I had good hygroscopicity, solubility, and stable spatial conformation based on apparent morphology, fourier transform infrared spectroscopy, and circular dichroism spectroscopy. When incorporated into pork patties, adding 15 g of F I per 100 g of pork patties (15% F I) significantly improved the cooking loss during repeated F-T cycles, and the cooking loss only increased by 18.52 percentage units after 7 F-T cycles. Moreover, F I effectively reduced the destruction of the microstructure of the pork patties. Overall, F I is expected to act as an antioxidant and water retaining agent to effectively inhibit food quality deterioration during F-T cycles.