接触式超声波辅助平板冷冻对胡萝卜冷冻速率的影响

Influence of Contact Ultrasound Assisted Vibrating Plate on the Freezing Rate of Carrot

超声波可以促进晶核形成,缩短冻结时间并且获得较高的冻结品质,但该技术目前多用于液态样品或浸渍冷冻过程,在固体果蔬样品平板冷冻过程中的应用未见报道。本文设计制作了一种接触式超声波辅助冷冻平板,用于固体果蔬的冷冻过程,并进行了三组实验:1)在-1℃施加10 s不同功率(0 W,122.6 W,178.7 W,229.8 W)的超声波;2)在-1℃施加178.7 W超声波,作用0 s,5 s,10 s,15 s;3)在不同阶段(预冷段,相变段,终了段)施加178.7 W的超声波10 s。分别研究了超声波的作用功率、作用时间、作用阶段等参数对胡萝卜冷冻速率的影响,结果表明:在相变阶段作用178.7 W的超声波10 s,能显著降低样品通过最大冰晶生成段的时间tcf和总冻结时间ttf,提高样品的冷冻速率。

Ultrasound can promote the formation of crystal nucleus, shorten the freezing time and get a higher quality freeze, but the tech- nology is currently used for the liquid samples or immersion freezing process, and solid samples were barely taken into account. In this pa- per, the contact ultrasonic assisted vibrating plate was designed and set up, which is used for the freezing process of solid fruits and vege- tables. The effects of ultrasound power, exposure time and phase stage on the freezing rate of the carrot were investigated. The experi- ments are divided into three groups： 1 ）applying ultrasound with different powers （0 W,122.6 W,178.7 W,229.8 W） for 10 s at - 1 ℃ ; 2） applying 178.7 W ultrasound at - 1 ℃ for 0 s ,5 s, 10 s, 15 s respectively; 3 ） applying 178.7 W ultrasound for 10 s during differ- ent 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 tof （characteristic freezing times） and ttf （ total freezing times） and increase the freezing rate of samples.