Application of Multi-frequency Ultrasonic Washer on Leafy Vegetables Cleaning

Cleaning is one of the key link in vegetables processing, which is vital for the quality. In this paper, the self-developed ultrasound and air-bubble washing devices were employed to wash a widely consumed leafy vegetable（lettuce）, and then the cleaning effects were evaluated using cleaning ratio and damage ratio as indicators.Results indicated that cleaning ratio of lettuces reached to 100% with a damage ratio of 12.89% using air-bubble cleaning technology under the following conditions: washing time of 40 s and lettuces weight of 500 g. While the cleaning ratio of lettuces reached to 100% with a damage ratio of 9.62% when lettuces of 750 g was washed with the ultrasonic cleaning device under the ultrasonic frequency of 68 kHz, ultrasonic power of 900 W and washing time of 40 s. These data demonstrated that the washing amount was increased by 50% while the damage ratio was reduced by 25.4% when lettuces were washed using ultrasonic cleaning technology under the same washing time and cleaning ratio. Therefore, ultrasonic cleaning technology displayed superior advantages.