Abstract: The aim of this study was to investigate the effects of different freezing methods on the emulsifying stability of myofibrillar protein. The changing trends of solubility, turbidity, particle size, Zeta potential and emulsifying activity index of chicken breast myofibrillar protein were measured after air freezing, immersion freezing and ultrasound-assisted immersion freezing at different ultrasound powers (125, 165, 205 and 245 W). The results showed that the emulsifying stability of myofibrillar protein with an appropriate ultrasound power (165 W) was significantly higher than that in the other groups (P < 0.05), as indicated by higher solubility and emulsifying activity index, and lower Zeta potential, turbidity, surface area average particle size D32 and volume average particle size D43. However, excessively high ultrasound power (245 W) could cause the aggregation and denaturation of the protein, consequently leading to its reduced emulsifying stability. These results indicated that ultrasound-assisted freezing with an appropriate power (165 W) can maintain the emulsifying stability of frozen chicken breast myofibrillar protein, which will provide a theoretical basis for the application of ultrasound-assisted freezing in meat products.

Key words: chicken breast; ultrasound-assisted freezing; myofibrillar protein; emulsifying stability