Effects of ultrasound-assisted low-salt curing on water retention, tenderness and in vitro digestive characteristics of grass carp (Ctenopharyngodon Idellus)

The implementation of innovative techniques to achieve low-salt strategies in cured products is a critical issue faced by the food industry. This study aimed to investigate the impact of ultrasound treatment on the quality of the low-salt air-dried fish. The results showed that compared to traditional liquid curing, ultrasound-assisted curing significantly increased the NaCl transfer rate, improved tenderness, and improved water retention and in vitro digestibility (p < 0.05). Microscopic observations revealed that ultrasound treatment substantially disrupted the muscle fiber structure, enlarging the spaces between fibers. Furthermore, ultrasound-assisted curing led to the unfolding of the spatial structure of myofibrillar proteins, enhanced intermolecular hydrophobic interactions, and promoted protein oxidation (p < 0.05), which are fundamental reasons for the improvement in fish quality. Thus, ultrasound treatment had a positive effect on fish curing, with the optimal parameters identified as 590 W for 78 min. Overall, the findings of this study provide evidence for the application of low-salt processing technology in fish products.