Dual-frequency ultrasound-assisted curing of catfish meat: Effects on efficiency and quality

• Dual frequency ultrasound reduced the curing time of catfish meat by 50%. • Accelerated uniform distribution of Na + and Cl − . • Improved water content and WHC. • Promoted the breakage of myofibrils, but did not cause protein degradation or loss. • Reduced protein oxidation and increased lipid oxidation. In order to improve the curing efficiency of fish meat and reduce spoilage, this study used the back meat of catfish as materials and compared the effects of single-frequency (20, 40, 60 kHz), dual-frequency (20 + 60, 20 + 40, 40 + 60 kHz), and triple-frequency (20 + 40 + 60 kHz) ultrasound-assisted on curing efficiency, with traditional curing as a control. It was found that at the target salt content of 1%, the time of dual-frequency ultrasound-assisted curing (20 + 60 kHz) was reduced from 40 min to 20 min, as well as the improved meat quality. The scanning electron microscopy (SEM) and energy dispersive X-ray analysis (SEM-EDS) results showed that Na + and Cl − were more evenly distributed in samples. The water holding capacity (WHC) and low field nuclear magnetic resonance (LF-NMR) results indicated that the water distribution in catfish meat was altered, with increased water content and WHC ( P < 0.05) and decreased cooking losses ( P < 0.05). Furthermore, scanning electron microscopy (SEM), tissue sectioning, myofibril fragmentation index, and trichloroacetic acid (TCA)-soluble peptide content analysis showed that the catfish tissue microstructure were damaged, but myofibrillar protein was not degraded or lost. The sulfhydryl, carbonyl, the peroxide value (POV) and the thiobarbituric acid reactive substances (TBARS) value showed that the protein oxidation was reduced ( P < 0.05) and lipid oxidation was increased ( P > 0.05). These results look forward to providing a data reference for applying ultrasound in fish curing and offering new ideas for achieving “reducing salt without compromising quality” in food.