Differences in chlorophyll loss at 13 degrees C for two broccoli (Brassica oleracea L.) cultivars associated with antioxidant enzyme activities
1998
Toivonen, P.M.A. | Sweeney, M.
Two broccoli cultivars which have been previously found to have large difference s in yellowing susceptibility were studied to determine if there was a relations hip between antioxidant capability and chlorophyll loss at a simulated retail di splay temperature. Greenbelt cultivar retained a stable chlorophyll content over 4 days at 13 degrees C, while Emperor cultivar showed a constant decline in chl orophyll content. These differences were not related to differences in water los s. Superoxide dismutase (SOD) and peroxidase (POD) activities were approximately 30% higher in Greenbelt than in Emperor. The ratio of superoxide dismutase to p eroxidase activity was also lower in Greenbelt. The susceptibility of Emperor to oxygen radical damage and lipid peroxidation is expected to be higher since an excessive SOD activity, with respect to POD activity, can potentially lead to en hanced hydroxyl radical formation. Catalase (CAT) activity was higher in Emperor , suggesting that catalase is not important in providing resistance to chlorophy ll loss in broccoli. Water soluble, nonenzymatic antioxidant activity was simila r for both cultivars. These results support the hypothesis that antioxidant prot ection offered by superoxide dismutase and peroxidase is important to retention of green color in broccoli.
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