以还原型抗坏血酸为代表物,分别研究超声清洗小白菜时,超声功率(0.05、0.15、0.25、0.35、0.45W/cm2),超声频率(28、40、50、135 kHz),清洗时间(5、10、15、20、25 min)等因素对小白菜水溶性营养素流失的影响。研究发现:随着频率减小,功率增大,时间延长,小白菜还原型抗坏血酸流失率增大;其中在超声频率28kHz,功率0.45 W/cm2超声清洗25 min后小白菜中还原型抗坏血酸流失率最大,达到61.36%。而在超声频率135 kHz,功率0.05 W/cm2超声清洗5 min后小白菜中还原型抗坏血酸流失率最小,为9.94%。

Reduced ascorbic acid,one of water-soluble vitamins,widely contained in fruits and vegetables,was studied for its loss under low power ultrasonic bath. The influence of ultrasonic power( 0. 05,0. 15,0. 25,0. 35,0. 45W / cm2),frequency( 28,40,50,135 kHz),cleaning time( 5,10,15,20,25 min) on the loss of reduced ascorbic acid were studied. The results showed that the loss rate of reduced ascorbic acid increased with the increase of ultrasonic cleaning power and the length of cleaning time. In contrast,the loss rate decreased with the increase of ultrasonic frequency. In addition,under the ultrasonic condition of 28 kHz and 0. 45 W / cm2,the loss rate of reduced ascorbic acid was the highest which was 61. 36% loss after 25 min ultrasonic treatment. At 135 kHz and 0. 05 W / cm2,the loss rate of reduced ascorbic acid was the lowest of 9. 94% loss after 5 min ultrasonic treatment.