INFLUENCE OF PRESTORAGE HEAT AND CALCIUM TREATMENTS ON LIPID-METABOLISM IN GOLDEN DELICIOUS APPLES

Heating 'Golden Delicious' apples for 4 days at 38 degrees and/or pres sure infiltrating the fruit with a CaCl2 solution after harvest, maint ains firmness and reduces decay during storage. The possibility that t hese beneficial effects involve changes in membrane lipid metabolism w as investigated. Lipids of hypodermal cortical tissue were analyzed af ter O, 1, 2 or 4 days at 38 degrees and after storage (15 weeks at 0 d egrees plus 1 week at 20 degrees) of fruit that were untreated (Ctl), heated 4 days at 38 degrees (HT), infiltrated with 2% CaCl2 (Ca) or he ated then infiltrated (HT + Ca) before storage. Overall, effects of HT were much more pronounced than those of Ca and effects of HT + Ca wer e intermediate between those of HT or Ca alone. An initial phase of me mbrane damage induced by heating indicated by glycerolipid loss over t he first 1-2 days, could explain why HT for less than 3-4 days has an adverse effect on post-storage quality. HT effects on plastids, includ ing accelerated chlorophyll and monogalactolipid loss, as well as caro tenoid accumulation, are likely to cause the distinct yellowing of the fruit. HT-induced reductions in steryl glycosides and cerebrosides pr ior to storage similar to those that occurred in Ctl and Ca fruit duri ng storage, and the phospholipid (PL) content of HT fruit after storag e was close to that of Ctl fruit at harvest. Also, the ratio of linole ate to oleate in PL was much higher in HT and HT + Ca than in Ctl frui t at the end of storage. One or more of these effects of HT on membran e lipids could be involved in the ultimate benefits to fruit quality. Published by Elsevier Science Ltd.