| Summary: | 碩士 === 國立中興大學 === 園藝學系所 === 101 === The purpose of this study is to investigate the potential improvement of postharvest fruit quality by using different preharvest bagging materials and postharvest treatments such as applied hot air, chitosan coating, vacuum and packaging method. Guava bagged with white paper showed that the maturity time was 2 weeks later than those bagged with polyethylene plastic containing inner expanded polystyrene net sleeve. Both before and after storage, the fruit quality including firmness, total soluble solid, ascorbic acid, and peel color was better when bagged with white paper compared to those treated with polyethylene plastic containing inner expanded polystyrene net sleeve. This result indicated that the fruit quality before storage can affect the fruit quality after storage.
Results from the guava treated with hot air at 55℃ for 2 to 4 hours, and then stored at 1℃ for 14 days, then moved to 5℃ for 7 days, and finally, rewarmed at 25℃ for 3 days revealed that those packed with polyethylene plastic containing inner expanded polystyrene net sleeve had less weight loss, minor heat injury, and retarded fruit softening than those without packing bag under hot air. The best fruit appearance was observed when treated with hot air for 2 hours before storage; however, there is no significant difference compared with the untreated group. ‘Di-Wan’ guava treated with 0.5%, 1.0%, 1.5% chitosan caused weight loss and increased total soluble solids after storage. Guava treated with chitson and then packed by using polyethylene plastic with inner expanded polystyrene net sleeve showed improved weight loss. Coating treatment with 1% chitosan plus package had best fruit appearance, but not significantly different from untreated group.
‘Jen-Ju’ guava could tolerate 0.4% oxygen under 25 ℃ for 7 days with no appearent hypoxic injury. Guava storage after vacuum packaging can effectively reduce fruit softening and chilling injury symptoms such as decay, water-soaking core, and vascular browning. In contrast, the pericarp showed severe browning and produced a small amount of anaerobic respiration metabolites. Using vacuum cleaner to vacuum the bag before sealing can effectively improve the pericarp browning and reduce anaerobic respiration metabolites. Fruit packed by polyethylene plastic containing inner expanded polystyrene net sleeve stored at 1℃ for 14 days, then moved to 5℃ for 7 days and rewarmed at 25℃ for 3 days demonstrated serious chilling injury symptoms without commercial value in all treatments except for the vacuum-packed fruits with the vacuum-package removed before rewarming at 25℃ for 3 days, which showed minor injuries in fruits, but still with on commercial value.
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