Peroxidase Distribution During Post Harvest In Brassica Rapa

Vegetables after harvesting activate defence and senescent processes that ultimately lead to tissue death. The browning causing a loss of quality of such products occurs in the post-harvest storage involves peroxidases and/or poliphenoloxidases. In this work peroxidases have been studied in broccoli from Brassica rapa cv sylvestris in different storage conditions (10°C, 4°C in air and 4°C in a modified atmosphere) up to 20 days from the harvest. The collected sample were divided in florets, stem and leaf blade. Peroxidase activities increased strongly in inflorescence as well as in leaf blades and decreased in stem when broccoli were stored at 10°C. The increase was slightly in those stored at 4°C and did not change under modified atmosphere. Native isoelectrofocusing (pH 3–10) revealed numerous peroxidase isoforms differently distributed in the plant tissues and whose activities changed in storage period. New isoforms were also evidenced. In addition ascorbate, that inhibited some peroxidase isoforms, strongly decreased in the post-harvest, mainly in the leaf blade near to the cut zone.The work was financed by SUN and MIUR (Progetto PRIN 2006077008)