Abstract: Emulsions prepared using myofibrillar protein (MP) as an emulsifier have poor stability under low NaCl condition. The effect of high-intensity ultrasound (HIU) treatment (frequency of 20 kHz, and power of 450 W) for different periods of time (0, 3, 6, 9, and 12 min) on the emulsifying properties of chicken MP under low NaCl condition (0.15 mol/L NaCl) and the stability and rheological properties of MP emulsions were investigated. The results showed that compared with the control group, the emulsifying activity index (EAI) and emulsion stability index (ESI) of MP significantly increased with increasing ultrasonic treatment time (P < 0.05). The Turbiscan stability index (TSI) and particle size of MP emulsions decreased significantly with increasing ultrasonication time, and the absolute value of the zeta potential significantly increased (P < 0.05). The rheological analysis showed that ultrasound treatment significantly improved the viscoelasticity of MP emulsions. The oil-water interfacial tension analysis showed that ultrasound treatment effectively enhanced the mobility of MP, and rapidly decreased the interfacial tension. Meanwhile, ultrasound treatment significantly increased the amount of adsorbed protein in MP emulsions (P < 0.05), indicating that ultrasound treated MP contributed to emulsion stability. As observed by cold-field scanning electron microscopy, the emulsion prepared with MP treated by ultrasound for 12 min had the smallest droplet size. In conclusion, ultrasound treatment can significantly improve the emulsion stability of MP under low NaCl condition, which provides a theoretical reference for the application of ultrasound treatment to reduced-salt emulsified meat products.

Key words: myofibrillar protein; ultrasound; low NaCl; emulsion stability; cold-field scanning electron microscopy