Physiological changes in the antioxidant system of broccoli flower buds senescing during short-term storage, related to temperature and packaging

The superoxide dismutase (SOD) and the antiradical activity (RSA) together with the phenylopropanoids, flavonoids and chlorophyll levels in flower bud tissue were estimated during short-term storage of broccoli Lord cultivar. Catalase (CAT) and peroxidase (POD) activities were detected in broccoli flower branchlets. The activity of SOD increased gradually at both storage temperatures (20 and 5 degreesC), while the RSA increased only in higher temperature. Increase in catalase activity was observed after 1-day storage of non-packaged broccoli at 20degreesC, followed by its decrease, and after 1- and 3-day storage of the packaged heads. In the case of low temperature the enzyme activity increased only after 10 days of storage. Storage of broccoli at room temperature caused the significant increase of peroxidase activity, while at low temperature (5 degreesC) activity of the enzyme rose after 10 days. During the storage, the accumulation of phenylopropanoids and flavonoids in broccoli flower buds was observed. The rapid decrease of chlorophyll was observed only in the case of broccoli heads stored at 20 degreesC. Applying of polyethylene foil to packaging of broccoli heads during storage in most cases decreased the SOD, CAT, POD antiradical activities and phenol content, and slowed down chlorophyll decomposition in flower buds. The obtained results emphasize the active role of antioxidant components of broccoli flower buds senescing during short-term storage, especially in intense stress conditions. (C) 2003 Elsevier Ireland Ltd. All rights reserved.