The effects of ultrasonic brine on the physicochemical properties, sensory quality and microstructure of low-sodium beef jerkies were investigated. Compared with control jerky brined in 1.5% NaCl solution, both of the direct reduction and partial replacement of 50% NaCl by KCl decreased the sodium content. Ultrasonic treatment resulted in sharp reduction in shear force. KCl substitution together with ultrasonic treatment caused the highest yield, a* value and water content, and the water activity of all groups were below 0.85. Only the direct reduction of NaCl had negative effects on the sensory quality. KCl substitution combined with ultrasonic treatment was the most suitable for producing low-sodium beef jerkies with high quality, possibly because the mixed salt had equal total salt content to control. Meanwhile, the cavitation and mechanical effects of ultrasound may unfold protein structure, increase myofibrillar fragmentation index and break the muscle fiber, thus improving the quality of beef jerky.

The effects of different levels of rutin (0, 0.05%, 0.1%, 0.2% and 0.3% w/v) and ethanol on the structure and gel properties of whey protein isolate (WPI) were examined. The results showed that the addition of ethanol promoted the gel formation of WPI. The addition of rutin increased the gel strength of WPI and maintained the water-holding capacity of the gel. Ethanol caused an increase in thiol content and surface hydrophobicity, but rutin decreased the thiol content and surface hydrophobicity of WPI. The particle size, viscosity and viscoelasticity of WPI increased at rutin levels of 0.2% and 0.3%, indicating that rutin caused cross-linking and aggregation of WPI, but rutin had no significant effect on the zeta-potential, indicating that electrostatic interactions were not the main force causing the changes in protein conformation and gel properties. Ethanol and rutin improved the gel properties of WPI possibly by inducing cross-linking of WPIs via hydrophobic and covalent interactions.