Analysis Of Apricot Postharvest Quality And Study Of Near Freezing Temperature Storage On Apricot

With excellent taste and sensory quality,apricot has became increasingly popular with consumers.The phenolic compounds in apricot are highly related to the antioxidant capacity of the fruit,while the sugars and organic acids make contrubitions to the consumer satisfaction.Thus,it is necessary to study the relations between these nutritional contents,antioxidant capacity and sensory qualities of apricot.Postharvest storage of fresh apricot can not be easy to last for long time.Since near freezing temperature(NFT)storage could effectively inhibit the postharvest ripening process of fruit and extend the storage period,we tried to storage apricot fruit at a near freezing temperature.The main contents and results are as follows:(1)Polyphenol composition and antioxidant capacities of peel and pulp tissues of six apricot varieties were determined.Variations in polyphenol and antioxidant capacity based on variety and harvest maturity were assessed.The results of principal component analysis revealed that(+)-catechin made the most important contributions to the antioxidant capacities of the pulp.Levels of phenolic compounds in the apricot peels were approximately 2-A times higher than those of the pulps.Quercetin-3-rutinoside may be substantially responsible for the antioxidant capacities of the peels.The late-maturing varieties tended to have higher levels of phenolic compounds and higher antioxidant capacities than the early-maturing varieties.The antioxidant capacities in green mature apricots were much higher than those of full mature apricots.(2)To learn how the major components make relations to the sensory quality of apricot fruit,seven apricot cultivars were used for principal component analysis and hierarchical clustering.The results revealed that fructose and sucrose were the prominent contributors to sweetness,and further contributed to sensory quality and consumer satisfaction of apricot.Malic acid was mainly responsible for sourness of apricots,although it was not the richest organic acid among all the apricot varieties.Hierarchical clustering analysis divided Xinjiang apricot cultivars into one cluster,which was prominent in consumer satisfaction.(3)A new NFT storage equipment was designed to ensure the temperature to be stable,and the temperature fluctuation of the new equipment was less than ±0.2 ?.Another two utility models of the NFT storage equipment were designed to be used on commercial refrigeration house.The combined use could also achieve the NFT storage of fruit and vegetable.The biological freezing point and super-cooling point of shushanggan' apricot were determined.The storage temperature was respectively set as-2.1??-1.7?for low mature apricot and-2.8 ??-2.4? for medium mature apricot.(4)NFT storage was firstly used to improve the quality of'shushanggan' apricot.Our results showed that both low-mature and medium-mature apricots could be preserved for 90 d by NFT storage,and still maintained better edible quality and consumer acceptability.Storage at NFT could delay the fruit senescence of apricots by suppressing ethylene production and respiration rate.In addition,NFT storage enabled apricot to delay the onset of the peak value of phenolic compounds and antioxidant activity,and maintained higher values in the fruit at end of the storage.NFT storage can be considered as a storage technology for improving storage quality and antioxidant capacity of fresh apricot.(5)The effects of NFT storage at-1.9 ? on postharvest ripening process and cell wall degradation of apricot was studied comparing to 0 ? and 5 ? storage.Our results indicated that NFT storage remarkably retarded color change and ripening index increase of apricot.NFT storage strongly inhibited the solubilization of Na2CO3-soluble pectin and cellulose,by the suppression of cell wall modifying enzymes and related genes expressions.Microscopic observation provided a direct evidence that NFT storage delayed pectin degradation and middle lamella dissolution of apricot,and maintained the integrity of cell structure.(6)Post-storage applications of exogenous ethylene and 1-methylcyclopropene(1-MCP)were performed in-1.9? stored apricot to regulate the ripening and softening process during shelf life.The results showed that poststorage ethylene treatment could accelerate SSC accumulation,organic acids degradation,color change and ripening process of cold-stored apricot,and could effectively improve the consumer acceptability of the fruit.Post-storage 1-MCP treatment strongly suppressed ethylene production in apricot during shelf life,causing the suppression of expression levels of pectin related genes encoding for pectin degraded enzymes.Microscopic observation provided a direct evidence that post-storage treatment of 1-MCP delayed pectin degradation and middle lamella dissolution of apricot,and delayed the softening process during shelf life.The regulation of ripening and softening process of apricot with post-storage treatment of ethylene or 1-MCP could be effective for improving consume acceptability or delaying fruit softening of the fruit.