MEMBRANE LIPID-METABOLISM, CELL-PERMEABILITY, AND ULTRASTRUCTURAL-CHANGES IN LIGHTLY PROCESSED CARROTS

We monitored changes in phospholipid (PL), steryl lipid, and glycolipid classes, cell permeability, and ultrastructure in wound-stressed tissues (shreds and disks) of carrots (Daucus carota L. 'Apache'), stored up to 10 days at 10 degrees C and 95% RH. Total PL rose 47% ten days after shredding, with phosphatidylcholine decreasing and phosphatidic acid increasing in relative abundance. Acylated sterol glycoside doubled after 2 days. Leakage of UV-absorbing metabolites from disks increased by 45% between 1 and 3 days storage. Extensive, storage-dependent accumulation of endoplasmic reticulum and attached ribosomes within vascular parenchyma cells occurred 10 days after wounding. Thus net synthesis of membrane lipid components occurred together with increases in permeability and the accumulation of phosphatidic acid. Membrane degradation and repair processes likely coexist during prolonged storage of lightly processed carrots.