Abstract: This study investigated the effects of ultrasound-assisted immersion freezing (UIF) under different ultrasonic powers on the freezing rate and quality of pork dumpling filling. The results showed that UIF significantly (P < 0.05) increased the freezing rate, and the sample treated with ultrasonic power of 90 W (UIF-90) took the shortest time to freeze. Compared with air freezing, UIF showed significantly lower levels of oxidation and cooking loss (P < 0.05). As the ultrasonic power increased, the L* and a* values increased first and then decreased, while no significant differences were observed in b* value (P > 0.05). The T21 and T22 relaxation times of the UIF-90 sample were the shortest, indicating that proper ultrasonic power levels could reduce the mobility of free water and immobilized water. To sum up, UIF significantly reduces the freezing time of pork dumpling filling at an appropriate ultrasonic power (P < 0.05) and improves the quality of meat filling.

Key words: dumpling meat filling; ultrasonic-assisted immersion freezing; freezing rate; dumpling filling quality