372 GRAPEFRUIT CANOPY POSITION AFFECTS CHILLING TOLERANCE AND FLAVEDO LIPID COMPOSITION

Abstract

The objective of this work was to determine if lipid composition of grape fruit flavedo tissue differed with canopy position and if changes in flavedo lipid composition occurred during the development of chilling injury (CI). `Marsh grapefruit were harvested from interior (IN) and exterior (EX) canopy positions and stored at 5C for up to 8 weeks. During storage, EX fruit developed severe CI, whereas IN fruit developed only trace CI. Electrolyte leakage from EX fruit flavedo increased during storage and significantly greater than from IN fruit At the time of harvest, flavedo oleate and linoleate, on a μg % basis, were higher in IN than in EX fruit During storage at 5C, the amount of oleate in IN fruit flavedo decreased and was similar to EX fruit after 4 weeks at 5C. The relative amount of flavedo linoleate decreased in IN fruit and increased in EX fruit during storage at 5C and following 8 weeks at 5C was higher in EX fruit than in IN fruit At the time of harvest, total lipid P in flavedo was higher in IN fruit than in EX fruit; during storage the amount of flavedo lipid P in IN fruit decreased and was equivalent to EX fruit following 8 weeks at 5C. Total sterols in flavedo did not differ with canopy position and remained constant during storage.