A novel technique using ozone micro bubbles to control microbial contamination and browning offresh-cut lettuce

摘要

Fresh-cut lettuce has become popular among consumers. However an increased number of food safety outbreaks associated with fresh-cut produce require investigations into novel microbial decontamination methods infresh-cut lettuce products. This study investigated the effects of a novel technique using ozone micro bubbles (0_3-MBs) on microbial control and quality of fresh-cut 'Cos' lettuce. Fresh-cut 'Cos' lettuce leaves were washed in 0_3-MBs (~0.S ppm) for S min at ambient temperature and compared withchlorinated water (NaOCl, 100 mg L~(-1), 5 min). For total bacteria counts, coliform counts and yeast and mould, 0_3-MBs treatment resulted into a 1-2 log reduction, which was similar to the result achieved by 100 mg L~(-1) chlorinated water. The amountof phenolic compounds of the lettuce was reduced by 03-MBs treatments. Washing with 0_3-MBs also inhibited PPO activity for up to six days of storage at 4°C which is correlated with a lower amount of quinone content during storage. An inhibitory effectof browning enzyme and substrate resulted in a lower browning symptom of fresh-cut lettuce during storage. These results indicate that O3-MBS could be an alternative sanitizer to chlorine for fresh-cut lettuce due to a bacterial inhibitory effect and retention of sensorial quality and browning control.