Postharvest Responses And Antioxidant Capacity In Chinese Bayberry Fruit

Postharvest responses of Chinese bayberry (Myrica rubra Sieb. & Zucc.) fruit were investigated using fruit from five red cultivars, Biqi, Hunanzhong, Wuzhong, Dongkui and Zaodamei as materials. Fruit from a single harvest for each cultivar were divided into three categories according to fruit colour, designated as immature, mature and ripe. Respiration rate, ethylene production, total soluble solids (TSS), titratable acidity (TA), individual soluble sugars and organic acids contents were determined every 3 h over 48 h at 20℃and 7 d at 0℃storage period plus 2 d shelf life at 20℃after harvest. The results showed that (1) Immature and mature fruit of all the cultivars underwent typical climacteric respiratory and ethylene behaviour, while ripe fruit did not exhibit any climacteric rise; (2) low temperature significantly inhibited respiration and ethylene production, which were sharply rised after shifting to shelf life at 20℃, and showed similar responses as storaged at 20℃directly; (3) the changes of ACC content, ACO and ACS activities were accordingly as ethylene production; (4) TSS and soluble sugars, TA and organic acids contents of all the cultivars substantially declined over storage, Postharvest life could be extended for up to 7 d by storage at 0℃, but with only a short subsequent shelf life because of rot development. (5) the PAL activity increased in immature and mature fruit, but decreased in ripe fruit, which was the same as the change of Cy-3-glu content, and CIRG showed positive relationship with Cy-3-glu content (r=0.96**) . Chinese bayberry fruit should be classified as a climacteric fruit, and our results show the importance of fruit maturity in terms of postharvest response, and CIRG can be used for appraisal the maturity of Chinese bayberry fruit.Immature, mature and ripe Chinese bayberry var. Biqi fruit were treated with 0.1, 1.0, 10.0μl/L of 1-MCP and 100.0μl/L of C₂H₄ for 12 h stored at 20℃. Results showed that (1) 1-MCP treatments delayed the ethylene climacteric peak of immature fruit for 12 h, while there was no effect on ripe fruit; ethylene treatment induced ethylene production of the fruit during storage; (2) all concentrations of 1-MCP treatment have more or less effect on fruit decay allievation. With 1.0μl/L of 1-MCP treatment, the decay rates after 60 h storage at 20℃were reduced 29.1, 48.6 and 21.4% in immature, mature and ripe fruit, respectively; (3) 1-MCP treatment had no significant effects on fruit TSS, while immature, mature and ripe fruit treated with 1.0μl/L of 1-MCP contained 3.7, 9.5 and 5.0% higher TA than control. In conclusion, 1.0 μl/L of 1-MCP treatment showed the best effects on controlling fruit decay and maintaining postharvest quality.Chinese bayberry var. 'biqi' fruit at commercial maturity was used as material in the ethanol vapour treatment experiment. Results showed that (1) 1000 μL/L of ethanol treatment reduced the decay rate by 12.9% after 3 d storage at 20℃ and by 11.2% lower after 5 d storage at 0℃, and there were no difference of ethanol residue in fruit tissue between ethanol treated fruit and the control; (2) 1000 μL/L of ethanol treatment did not have any deleterious effects on fruit quality, but resulted in an 14.6% increase in the accumulation of anthocyanins in the fruit after stored at 0℃ for 5 d and shift to shelf life at 20℃ for 2 d.Total phenolics, flavonoids, anthocyanins, Cy-3-glu contents and antioxidant capacity were investigated by using fruit from seven Chinese bayberry cultivars, i.e. Shuijing, Fenhong, Wuzhong, Hunanzhong, Dongkui, Zaodamei and Biqi, as materials. Results showed that (1) contents of total pehonlics, total flavonoids, and Cy-3-glu in the fruit were significantly correlated with fruit color and maturity (r>0.75); (2) Cy-3-glu accounted for only 0.69%o of fruit weight while had contributed at least 86% to the total antioxidant capacity (by both FRAP and DPPH) in Biqi fruit; there was no detection of Cy-3-glu in Shuijing fruit whose antiodidant was 1/4 of Biqi, what is the main antioxidant in Shuijing fruit needs further research; (3) greater fruit maturity was associated with higher levels of all the bioactive components and antioxidant capacity, and phenolic content as well as antioxidant capacity increased during postharvest storage of Biqi and Wuzhong fruit held at either 20℃ for 2 d or 0℃ for 5 d, from immature to ripe fruit, two cultivars increased about 5.3 and 3.8 times of Cy-3-glu content during 20℃ storage, and whose antioxidant capacities increased accordingly.