Résumé :
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Effects of time and storage atmosphere on relaxation properties in persimmon fruit (Diospyros kaki cv Fuyu) were investigated by nuclear magnetic resonance (NMR) imaging during the five weeks following commercial harvest. There were two treatments (n = 4): one in which fruit were hermetically sealed in individual polyethylene bags (modified atmosphere or MA treatment), and another sealed in individual perforated bags (control). Fruit were stored at 7 degrees C for 4 weeks (conditions conducive to development of chilling-injury), before being removed to 20 degrees C for 3 days to simulate poststorage shelf conditions. Every week, and at the end of the shelf-life period, a series of H-1 NMR images of median transverse and longitudinal planes were acquired from each fruit for calculation of spin-lattice (T-1) and spin-spin (T-2) relaxation times. Relaxation times associated with the flesh, vasculature and locules in transverse sections, and flesh from basal, median and distal regions of longitudinal sections, were significantly shorter in MA-treated fruit, although no T-2 treatment difference was noted with vasculature. MA-treated fruit were further distinguished from controls in that all tissues exhibited a sharp increase in T-1 (but not T-2) relaxation between the second and third weeks in cold storage.
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