Ultrasound can promote the formation of crystal nucleus

shorten the freezing time and get a higher quality freeze

but the technology is currently used for the liquid samples or immersion freezing process

and solid samples were barely taken into account. In this paper

the contact ultrasonic assisted vibrating plate was designed and set up

which is used for the freezing process of solid fruits and vegetables. The effects of ultrasound power

exposure time and phase stage on the freezing rate of the carrot were investigated. The experiments are divided into three groups: 1）applying ultrasound with different powers (0

122.6

178.7

229.8 W) for 10s at -1 ℃; 2）applying 178.7 W ultrasound at -1 ℃ for 0

5

10

15 s respectively; 3）applying 178.7 W ultrasound for 10 s during different phase stages. The results showed that the optimum condition is applying 178.7 W ultrasound for 10 s during transition phase，which can significantly reduce the tcf (characteristic freezing times) and ttf ( total freezing times) and increase the freezing rate of samples.