| Loquat (Eriobotrya japonica Lindl.) and peach(Prunus persica (L) Batsch) are characteristic fruit of Zhejiang province. The loquat fruit ripen in early summer, and when ripe, are spherical or oval in shape, orange yellow or white in color, with a thin, tough skin, and soft, juicy flesh. Loquat and peach fruit are famous for their good taste and nutritive value. The harvest season of these fruit is usually hot and rainy, and hence unfavorable for storage and transportation. Because of this, large postharvest losses can occur. In view of this, it is important and necessary to conduct in-depth studies on the mechanism of chilling injury and anti-chilling injury technology of the loquat and peach fruit.There were big differences in the low temperature storability and quality of different varieties of loquat fruits. Red loquat cultivas, included "Dahongpao", "Jiajiao" and "Dayayangdun", showed fruit firmness increased steadily, and fresh juice percentage decreased. The changes of fruit firmness and fresh juice percentage were the characteristics of tissue lignification. In contrast, white loquat cultiva, "Baisha", was not in obvious chilling injury during storage. The chilling injury of red loquat cultivas was closely related to the increase of the activities of PPO, POD and PAL. Although the"Baisha" loquat not had a chilling injury in the 0～1℃, it showed high decay rate and TSS, TS and Vc content decreased rapidly after 50 d storage. Loquats (Dahongpao) had the best storage qualities among varieties and decay rate had reached 8.2%after 50 days storage. However, they were easy to be harmed by chilling injury. Loquats (Dayayangdun) showed moderate ration of sugars to acids, rich flavor, good taste, and with no apparent lignification phenomenon.There were big differences in the low temperature storability and quality of different varieties of loquat fruits. Lower temperature storage, chilling injury occurred with symptoms of lignification, tissue browning, and a decrease in percentage juice, percent soluble solids, titratable acidity and vitamin C, increase in electric conductivity, lignin content and lignification enzyme activities.Short-term N2 pretreatment, hypobaric storage and MAP could inhabit occurring of the chilling injury of the loquat.The loquat fruits with 8h N2 pretreatment were effective in delaying senescence. Short-term N2 treatment could maintain higher level of total soluble solid and titratable acidity, reduce decay incidence and increases in activities of SOD and CAT increasing. In contrast, lower levels of membrane permeability, malondialdehyde (MDA) content, superoxide anion generation rate and LOX activities were observed in short-term N2 treatment fruit. During the storage, the higher ability of the enzymatic antioxidant systems was found in the loquat treated with short-term N2 treatment.Hypobaric storage significantly reduced the rates of respiration and ethylene production, delayed the onset of their peak values, inhibited browning index, and maintained high contents of total soluble solids, titratable acidity and vitamin C. Moreover, hypobaric storage inhibited the increase of POD and PAL activities, reduced their peak values, delayed the increases of flesh firmness and lignin content, inhibited the decrease of extractable juice rate, thereby maintaining good eating quality and extending the storage life of cold-stored loquat fruit.MAP were effective in reducing the increase of respiration and ethylene production, firmness, decay rate, lignin content, maintaining high contents of titratable acidity and vitamin C.The storage qualities of peach were much difference between seventy to eighty percent maturity and ninety percent maturity. Compared to fruits of seventy to eighty percent maturity, fruits of ninety percent maturity had strong chilling tolerance and kept good quality during low temperature storage, which showed that there were lower flesh firmness, slight browning index, high juicy rate, contents of soluble solids content, titratible acidity and ascorbic acid and ethylene production rate and respiration rate. This was related to inducing the increase in activities of SOD and POD, reducing accumulation of free radical and alleviating chilling injury for juicy peaches with high maturity grade. Thus, the best harvest maturity grade for juicy peaches storage performed well was ninety percent maturity. Short-term NO pretreatment, hypobaric storage and MAP combined with 1-MCP could improve the storage quality of the peach.The peach fruits with NO pretreatment were effective in extending the shelf-life. Short-term NO treatment could maintain higher ration of sugars to acids, firmness and vitamin C, reduce the increase of respiration and ethylene production, membrane permeability, MDA content. During the storage, the higher ability of the enzymatic antioxidant systems was found in the peach treated with short-term NO treatment.Hypobaric storage significantly extended the shelf-life of the peach. It was found that the storage qualities were varied with different pressures. The appropriate pressure was 50-60 kPa.The peach fruits, which treated by 1-MCP and MAP, could reduce the increase of respiration, delay senescence, keep firmness and maintain percent soluble solid. At the same time, lower levels of activities of PE, PL and PG were observed in MAP combined with 1-MCP treatment fruit. And MAP combined with 1-MCP treatment fruit had higher activities of SOD and CAT, which reduced the accumulation of free radical, slowed down senescence course. |
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