ISHS Acta Horticulturae 517: XXV International Horticultural Congress, Part 7: Quality of Horticultural Products
CHANGES OF PHENOLICS OF LITCHI FRUIT DURING POSTHARVEST STORAGE |
| Authors: | D.L. Zhang, P.C. Quantick |
| Keywords: | bound phenolics, browning, free phenolics, Litchi fruit, phenylalanine ammonialyase, polyphenol oxidase |
| Abstract:
Litchi (Litchi chinensis Sonn. cv. Huaizhi) fruit were stored at ambient temperature and at 4°C for 7 days and 35 days respectively to investigate the changes in free phenolics, bound phenolics, total phenolics, PPO (Polyphenol oxidase) activity, PAL (Phenylalanine ammonialyase), and browning of the fruit peel during postharvest storage. A 0.03 mm thick polyethylene film and TBZ (0.1% Thiabendazole) were used in packaging and decay control of the fruit during storage. Results indicate that with the increase of ambient storage time the contents of total phenolics and free phenolics decreased continuously, while bound phenolics remained at the same level. However, with storage at 4°C the content of total phenolics decreased continuously and the content of bound phenolics decreased slightly during the first 5 days and returned to and stablised at the original level afterwards. The content of free phenolics had a slight increase during the first 5 days and then decreased. With the increase of browning, the contents of total phenolics and free phenolics decreased, while bound phenolics remained at a steady level whenever the fruit were stored at ambient or 4°C. There were gradual increases in both PPO and PAL activities in the fruit stored at both ambient and 4°C and then decreases corresponding to a fall in free phenolics. Therefore, we suggest that free phenolics are the main source of browning substrates during storage of Litchi fruit and PPO activity is closely related to the level of free phenolics while PAL has some contribution to the level of free phenolics. | |
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