PHOSPHOLIPID, GALACTOLIPID, AND STERYL LIPID-COMPOSITION OF APPLE FRUIT CORTICAL TISSUE FOLLOWING POSTHARVEST CACL2 INFILTRATION

Fruit firmness and membrane lipid composition were evaluated in outer cortical tissue of 'Golden Delicious' apples, which were pressure-infi ltrated with distilled water, or 2 or 4% CaCl2 solutions at harvest. A fter six months storage at 0 degrees, fruit were held at 20 degrees fo r 1, 7 or 14 days and then evaluated. During storage at 0 degrees, fir mness had decreased by 20% in water-infiltrated fruit, but by only 6% in fruit infiltrated with 4% CaCl2. During the span of 7 to 14 days at 20 degrees, firmness decreased more rapidly in water-infiltrated frui t compared with CaCl2-infiltrated fruit. Reductions in specific phosph olipids (primarily phosphatidylcholine, phosphatidylethanolamine and p hosphatidylinositol) occurred after transfer to 20 degrees but were la rgely independent of the infiltration treatment. Steryl glycosides, ac ylated steryl glycosides, monogalactosyldiacylglycerol and digalactosy ldiacylglycerol concentrations were positively correlated to CaCl2 con centration of infiltration solutions, and a large, transient increase (35-37%) in acylated steryl glycoside concentration occurred during th e first 7 days at 20 degrees in CaCl2-infiltrated fruit. In contrast, acylated steryl glycosides decreased by 19% in water-infiltrated fruit over the same time interval. Overall, the results indicate that CaCl2 infiltration may delay galactolipid breakdown, increase the rate of s terol conjugation, and thus affect membrane organization and function during postharvest life of apple fruit.