Comparative Study on Efficacy of Sanitizing Potential of Aqueous Ozone and Chlorine on Keeping Quality and Shelf-life of Minimally Processed Onion (Allium Cepa L.)

The increased cases of food-borne outbreaks associated with microbial contamination of fresh-cut fruits and vegetables have underlined the importance of safe and effective sanitizing agents in the food industry. This study was conducted to comparatively evaluate the sanitizing effects of optimized aqueous ozone conditions (5 ppm dissolved ozone for an exposure time of 8 min and aqueous pH of 3.01), 100 ppm chlorine and water washing treatments on the cut slices (4 +/- 1 mm) of onion (Allium cepa L). The treated samples were packed in cling wrapped tray packs and were stored under ambient (26.8-37.3 degrees C, 10-57% RH) as well as refrigerated conditions (5 +/- 1 degrees C, 90 +/- 1% RH) and were monitored for quality parameters at regular intervals (1 day for ambient and 5 days for refrigerated storage conditions). Among the samples stored under ambient conditions, aqueous ozone-treated samples had a significantly better shelf life (2 days) as compared to chlorine-treated (1 day) samples. Whereas, under refrigerated storage conditions, a higher shelf life was observed for minimally processed onion treated with chlorine (16 days) followed by ozone (13 days). The microbial load on the ozone and chlorine-treated produce was 8.4 log (cfu g(-1)) and 7.4 log (cfu g(-1)) respectively, after 2 weeks of refrigerated storage. Optimized conditions of aqueous ozone were observed to yield a competitive sanitizing efficiency as compared to 100 ppm chlorine.

Automated summary

This study compared the sanitizing effects of aqueous ozone, 100 ppm chlorine and water washing treatments on cut onion slices, finding that aqueous ozone treatment had a longer shelf life at ambient temperatures, while chlorine treatment had a longer shelf life under refrigerated conditions. Additionally, it was observed that optimized conditions of aqueous ozone were competitive in sanitizing efficiency compared to 100 ppm chlorine.