Postharvest Ca infiltration delays senescence and improves storage quality of apple fruit, but the consequences on membrane lipid composition have received little evaluation. We studied changes in galactolipids (mono- and digalactosyl-diacylglycerol; MGDG and DGDG) and sterol conjugates (sterol glycosides and acylated sterol glycosides; SG and ASG) in `Golden Delicious' cortical tissue. Fruit were pressure-infiltrated with CaCl, at harvest (0, 2, or 4% w/v), stored for 6 months at 0C, and evaluated during subsequent exposure to 20C. MGDG, SG and ASG concentrations were greater in Ca-infiltrated fruit (CIF) than in control fruit. A 35-37% increase in ASG occurred during the first 7 days at 20C in CIF, when ASG decreased by 19% in control fruit. Ca infiltration may delay degradation of plastid membranes and increase sterol conjugation during apple fruit ripening.