| Low temperature storage was the most effective method for prolonging the shelf-life of Chinese olive (Canarium album (Lour.) Raeusch) fruits, but Chinese olive fruits were very susceptible to chilling injury during cold storage, resulting in quality deterioration and shortening storage life. Hot treatment was a physical preservation method with non-toxic and non-pesticide, which could raise the chilling tolerance of chilling-sensitive ftuits and vegetables.’Tanxiang’Chinese olive (Canarium album (Lour.) Raeusch cv. Tanxiang) fruits were used as the experiment material, which was the chief Chinese olive cultivar in Fujian Province of China. The optimum conditions of hot air treatment for inducing chilling tolerance and alleviating chilling injury of Chinese olive fruits were researched and developed during cold storage at (2±1)℃and the relationships between hot air treatment induced chilling tolerance and the changes of physiological quality, energy metabolism, active oxygen metabolism, metabolism of membrane lipids and phenolic metabolism of Chinese olive fruits during cold storage at (2±1)℃were investigated in this paper. The rusults were as follows:1. Pre-treated with hot air at38℃for30minutes could significantly decrease chilling injury of cold-stored Chinese olive fruits. There was a certain effect of alleviating chilling injury of cold-stored Chinese olive fruits when the fruit pre-treated with hot air at30℃for45minutes, while pre-treated with hot air at30癈for45minutes could accelerate the degradation of pericarp chlorophyll and promote the disruption of the integrity of cellular membrane structure of Chinese olive fruits during cold storage. Whereas, pre-treated with hot air at40℃for30minutes,42℃for45minutes,50℃for15minutes or60℃for15minutes could promote the occurrence of chilling injury of cold-stored Chinese olive fruits. From the results it could conclude that pre-treated with hot air at38℃for30minutes could be used as the opiimum conditions of hot air treatment for inducing chilling tolerance and alleviating chilling injury of Chinese olive fruits during cold storage.2. Pre-treated with hot air at38℃for30minutes delayed the increase of chilling injury index, respiration rate and cell membrane relative leakage rate of fruit, browning index in pericarp and browning degree in pulp, inhibited the the degradation of pericarp chlorophyll. Pre-treated with hot air at38℃for30minutes induced the decrease of pericarp ATP content, delayed the decrease of pericarp ADP content and remained the stability of pericarp AMP content, which increased the accumulation of pericarp energy charge in anaphase storage day. Pre-treated with hot air at38℃for30minutes also delayed the decrease of ATP content and ADP content in pulp and inhibited the generation of pulp AMP content, which maintained relatively higher energy charge level in pulp of cold-stored Chinese olive fruits. From the results it can be concluded that hot air treatment alleviating chilling injury and improving quality of cold-stored Chinese olive fruits may be due to maintaining the integrity of cellular membrane structure and a higher energy charge level of Chinese olive fruits.3. Pre-treated with hot air at38℃for30minutes promoted the increase of SOD activity from day60to day80, CAT activity from day100to day120, APX activity and GSH content from day80to day120in pericarp of cold-stored Chinese olive fruits, reduced pericarp O2production rate, pericarp MDA content and fruit chilling injury index, and delayed the peak in O2production rate of cold-stored Chinese olive fruit. Pre-treated with hot air at38℃for30minutes also delayed the decrease of SOD activity from day0to day80, CAT activity, APX activity from day0to day100, GSH content from day40to day120and carotenoid content in pulp of cold-stored Chinese olive fruits, inhibited O2production rate, MDA content and browning degree in pulp of cold-stored Chinese olive fruits. From the results it can be concluded that hot air treatment could enhance the ability of reactive oxygen scavenging, inhibit the membrance lipid peroxidation and maintain the stability and integrity of cellular membrane structure of Chinese olive fruits during cold storage.4. Pre-treated with hot air at38℃for30minutes decreased fruit chilling injury index, pericarp LOX activity and lipase activity of cold-stored Chinese olive fruits. The unsaturated fatty acids in pericarp, such as palmitoleic acid (C16:1), linoleic acid (C18:2) and linolenic acid (C18:3) increased, while the saturated fatty acids in pericarp, such as myristic acid (C14:0), palmitic acid (C16;0) and stearic acid (C18:0) decreased, and index of unsaturated fatty acids (JUFA) and unsaturated degree of fatty acids in pericarp increased. Pre-treated with hot air at38℃for30minutes also decreased browning degree, LOX activity and lipase activity in pulp of cold-stored Chinese olive fruits. The unsaturated fatty acids in pulp, such as palmitoleic acid (C16:1), linoleic acid (C18:2) and linolenic acid (C18:3) increased, while the saturated fatty acids in pulp, such as myristic acid (C14:0) and palmitic acid (C16:0) decreased, and it inhibited the decrease of index of unsaturated fatty acids (IUFA) and unsaturated degree of fatty acids in pulp. From the results it can be concluded that hot air treatment alleviating chilling injury of cold-stored Chinese olive fruits may be due to decreases of LOX activity and lipase activity, which may reduce the degradation of unsaturated fatty acids of membrane lipids and maintain higher unsaturated degree of fatty acids, in turn, may cause an increase of the fluidity of the membrane lipid, and a decrease of the temperature of phase changes of membrane lipid, resulted in improving chilling tolerance of cold-stored Chinese olive fruits.5. Pre-treated with hot air at38℃for30minutes decreased browning index, PPO activity and POD activity from day0to day20and from day60to day120in pericarp of cold-stored Chinese olive fruits, delayed the decrease of PAL activity, polyphenol content and flavonoid content in pericarp. Pre-treated with hot air at38℃for30minutes also decreased browning degree and activities of PPO and PAL in pulp of cold-stored Chinese olive fruits, increased POD activity from day40to day120and delayed the decrease of contents of polyphenol and flavonoid in pulp. From the results it can be concluded that hot air treatment alleviating chilling injury of cold-stored Chinese olive fruits may be due to maintaining the integrity of cellular membrane structure and the normal compartmentation of phenolic substrates and phenolase of Chinese olive fruits, which inhibit the contact and catalytic oxidation of phenolase to phenolic substances. |
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