Phytochemical Enhancement in Broccoli Florets after Harvest by Controlled Doses of Ozone

The objective of this work was to examine the effect of controlled doses of O-3 (0, 5 mu L L-1 of O-3 for 60 min, and 5 mu L L-1 of O-3 for 720 min) on the quality and phytochemical content of broccoli florets during postharvest storage. The optimal dose was found at 5 mu L L-1 of O-3 for 60 min, from the color retention of broccoli florets exposed to the gas treatment. Overall, the antioxidant capacity of the florets was significantly affected by both doses of O-3 compared to the non-exposed florets. The profile of glucosinolates was determined for up to 14 days in broccoli florets stored at 4 degrees C by LC-MS. The amount of total glucobrassicins and total hydroxy-cinnamates in florets significantly (p < 0.05) improved by the application of 5 mu L L-1 of O-3 for 60 min compared to non-treated florets. The up-regulation of genes of the tryptophan-derived glucosinolate pathway was observed immediately after both treatments. The gene expression of CYP79A2 and CYP79B3 in broccoli was significantly higher in broccoli florets exposed to 5 mu L L-1 of O-3 for 720 min compared to non-exposed florets. Although enhancement of secondary metabolites can be achieved by the fumigation of broccoli florets with low doses of ozone, quality parameters, particularly weight loss, can be compromised.