| Strawberry fruit is highly edible and very popular with customers. However, it is fragile for its soft and juicy texture. During storage and transportation, strawberry fruit is easily wounded which could cause serious deterioration and loss of quality. Therefore, the research on change of physiology and quality in postharvest strawberry is conducted. In order to induce the economic loss and improve the commodity quality of strawberry fruit, it is important to know the mechanism of mechanical wounding and to adopt some effective measures. In this study, wounded postharvest strawberry is treated with two physical measures. The effects of the two treatments on the rate of deterioration and quality are researched and analyzed from the point of physiology and biology.UV-C and hot air treatments were used in wounded postharvest strawberry to study the physiological effect and quality change. Strawberry(80%of mature) without any mechanical injury was harvested from orchard and transported into laboratory in2hours. Uniform size of strawberries were selected and wounded by cutting into two halves along the stem line. The wounded strawberry was stored at20±1℃, RH85-90%(avoid light) after treatment with4.1KJ/m2UV-C. Respiration rate, ethylene production, firmness, rate of deterioration and MDA were assayed. The antioxidant substances such as flavonoids, total phenol, anthocyanin, PPO, POD, H2O2, and O2-were also determined. The results indicated that UV-C treatment reduced the rate of deterioration effectively. The respiration rate and ethylene production were significantly inhibited and MDA content was reduced also by UV-C treatment. The anthocyanin content was significantly higher than control. H2O2content, O2-production rate and DPPH radicals scavenging rate were significantly reduced by UV-C. The activity of POD was lower in the control at the beginning. However, it increased higher later. UV-C treatment inhibited the total phenolics content and the activity of PPO, therefore, a reduced degree of browning was observed. The sensory quality was better in the treatment. These results indicated that UV-C treatment could reduce the injury in wounded strawberry and the reason mainly attributed to the regulation of physiological and antioxidant substances metabolism in wounded strawberry fruit. And a good quality of postharvest strawberry fruit was maintained.Wounded strawberry was treated in hot air (45℃) for3h. The results showed that HAT reduced the respiration rate, MDA content, electrolyte leakage and inhibited the ethylene production of wounded strawberry fruit. The rate of deterioration was also induced significantly. The rate of fruit organic substance consumption was reduced. Meanwhile the membrane lipid peroxidation was inhibited and then reduced the injury caused by mechanical wounding. The flavonoid content kept on increasing from day1to day4in the treatment, while it decreased in the control from day2. HAT inhibited the increase of the total phenol contents. The activity of APX reduced from day2to5, but the activities of POD and PPO increased significantly. The H2O2contents, O2-production rate and DPPH radical scavenging rate were significantly lower in the treatment than in the control. So we concluded that the generation of free radicals was inhibited significantly by HAT and the excessive free radicals injury was reduced after mechanical wounding. These results suggest that HAT can reduce the wound injure, mainly by regulating the physiology quality and antioxidant substances metabolism.The overall research showed that HAT and UV-C treatment regulated the physiological and antioxidant substances metabolism in wounded strawberry fruit. The treatments reduced the injury caused by mechanical wounding stress and kept good quality during storage. |
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