Post-harvest quality of lettuce treated with ozonised water in a microbubble system

Abstract

ABSTRACT This study aimed to determine the post-harvest quality of lettuce treated with ozonised water obtained in a microbubble system. The inlet ozone concentration was fixed at 3.5 mg L−1, which allowed obtaining 1.60 mg L−1 of ozone in the water. Six treatments were adopted: (i) control (untreated lettuce); (ii) ozonised water/5 min; (iii) ozonised water/10 min; (iv) oxygen/5 min; (v) oxygen/10 min; and (vi) chlorine/15 min. After the treatments, the samples were stored at 5°C and at a relative humidity of 80%. Microbiological and physicochemical analyses were performed immediately after ozonation (day 0) and after 3 and 6 days of storage. Reductions in the count of aerobic mesophiles and molds and yeasts were observed, immediately after the treatments with ozonised water. For the treatments ozonised water/5 min and ozonised water/10 min, the reductions of aerobic mesophiles were equal to 0.71 and 1.59 log reduction respectively, when compared to the control. Despite the significant increase in the leakage of electrolytes, especially when it was adopted exposure time to ozonated water of 10 min, it was considered that the conditions adopted favour the lettuce sanitation, without causing changes that make the product non-tradable.