Comparative study on physiological and metabolic responses of crayfish to ozone micro-nano bubbles and ultrasound washing.

Maintaining the well-being of living aquatic products before processing is crucial to guarantee best food quality. This study investigated the different effects of ozone micro-nano bubbles washing (OMW) and ultrasound washing on the well-being of living crayfish, one of the most economically valuable freshwater aquatic products in China. It has been found that OMW was a gentler and more effective alternative to traditional ultrasonic washing (UW) that reduced physical damage, thus leading to enhanced living vitality, increased intestinal content evacuation rate, and improved surface cleanliness of crayfish before processed as aquatic food. These improvements were attributed to the milder physical force generated by bubbles contraction and collapse than the cavitation and mechanical effects of UW. In addition, the strong cavitation, mechanical, and thermal effects of UW impaired the antioxidant system of crayfish, leading to the severe hepatopancreas damage as indicated by the substantially elevated activities of alanine aminotransferase and aspartate aminotransferase. Moreover, OMW significantly lowered the lactate dehydrogenase activity and reduced lactic acid accumulation due to decreased oxidative stress, thereby preventing acidosis in crayfish. These findings demonstrated that OMW was a milder yet more effective approach to improve the well-being of living aquatic products, thus maintaining their vitality and quality prior to processing into foods, suggesting its great potential as a pretreatment technology for applications in the aquatic food industry.