| Apple,as one of the highest yields and consumptions fruits in the world,with its features of sweet,crispy,juicy and nutritious,has won the favor of consumers.As respiratory climacteric fruits that regulated by ethylene during the post-harvest storage,fruit hardness drop and flavor deterioration occur during storage,which eventually leads to the decrease of edible quality and commercial value.Also,as a natural and environmental preservative,1-MCP could be applied to the preservation of Fuji and Hanfu apples,which is of important significance to the storage and preservation of apples.Given this,in this experiment,Fuji and Hanfu apples were used as the research objects.Firstly,the shelf quality and volatile substances of fresh fruits were compared to study the quality differences between Fuji and Hanfu apples in fresh fruits.Putting raw data into SIMCA 15 software,principal component analysis(PCA)and orthogonal partial least squares-discriminant analysis(OPLS-DA)were established to seek the fruit differences between Fuji and Hanfu apples from a new perspective in the aim of providing a solid basis for the qulity judgaement and preservation.Then the fresh fruits were put into BW-120 controlled freezing point storage(-0.5~-0.2℃),which were taken out after 10,11 and 12 months of storage and tested on the shelf life at room temperature(25~30℃),respectively.The effects of different storage periods on Fuji and Hanfu fruits were compared by measuring fruit quality and volatile substances.Finally,the effects of 1-MCP(1.0μL/L)treatment on the quality of Fuji,Hanfu and Hanfu planted in the mountain were studied.Moreover,the effects of 1-MCP treatment on the activity of the cell wall enzymes(polygalacturonase PG,cellulase,Cx)and intracellular enzymes(amylase)related to softening process,and volatile substances related enzymes(Lipoxygenase LOX,Hydroperoxide lyase HPL,Alcohol acyltransferase AAT,Alcohol dehydrogenase ADH and Pyruvate decarboxylase PDC)were discussed,the optimum storage period and storage methods of different varieties were determined.Results of the experiment are as follows:In the comparison of fresh fruits shelf quality between Fuji and Hanfu apples,in terms of fruit color,Hanfu apples showed redder in color,while Fuji apples were brighter;in terms of the intrinsic quality(Soluble solids TSS,Titratable acid TA,VC)of fruits,Hanfu apples contained higher nutrition quality,and Fuji apples performed lower respiration intensity and ethylene production rate;in terms of textural parameters,Fuji apples ran better score in peel crispness and average hardness of flesh,while the Hanfu apples performed better in peel toughness;in terms of volatile substances,the contents of volatile substances in Hanfu apples were higher that of Fuji fruit expect on the 0d of shelf life,and the contents of volatile substances reached the maximum on 21 d of shelf life,the total ester content of Fuji apple was higher,the total aldehydes and alcohols contents of Hanfu apple were higher.Conclusions are made on the basis of comprehensive considerations as Fuji fruits could better maintain the textural parameters than Hanfu fruits in the early stage of shelf life,Hanfu apples are redder than Fuji apples,while Fuji apple are brighter,however the contents of volatile substances of Hanfu apples are overall higher than Fuji apples.In the comparison of Fuji and Hanfu fruits quality after storage(10,11,12 months),in terms of fruit color,Hanfu apple showed redder in color during shelf life,while Fuji apple’s brightness higher,and effects of different storage periods on L*,a* and b* values of Fuji and Hanfu fruits were relative low,with the extension of shelf life,the brightness and redness both dropped,quality of color and luster deteriorated;in terms of the intrinsic quality(TSS,TA,VC)of fruits,with the increasing of the storage time,the nutrition quality of fruits decreased gradually,the respiration intensity of Fuji fruits were always higher than the Hanfu fruits,both of which presented a trend of first increased and then decreased,and hit their peaks on the shelf life 14 d,the respiration intensity started to decrease on the 21 d due to the slow-down of fruits’ metabolism.In terms of textural parameters,after 10 months of storage,Fuji apples significantly higher than Hanfu fruits in terms of hardness,brittleness,average flesh hardness,peel brittleness,peel intensity,peel rupture depth and so on,Fuji apples performed better in the corresponding hardness,brittleness,average flesh hardness,peel brittleness,peel intensity,peel rupture depth after 11 months of storage,the hardness,brittleness,gumminess,chewiness,elasticity of Hanfu apples were higher than Fuji fruits after 12 months of storage.In terms of volatile substances,the contents of volatile substances in Hanfu apples were higher,after 12 months storage,the volatile substances in fruits decreased greatly,with the increasing of the storage time,the total contents of volatile substances gradually decreased during shelf life.In conclusion,the quality of fruit is ensured of Fuji and Hanfu apples after 10 months of storage,which have much significance for ensuring the commercial value.In the comparison of the Fuji,Hanfu and Hanfu planted in mountain fruits after 10 and 11 months of storage with 1-MCP treatments,the results showed that 1-MCP could maintain TSS contents at a relatively high level,the TA contents of Hanfu planted in mountain fruits was the highest among the three varieties and with a changing pattern of Hanfu planted in mountain > Hanfu > Fuji fruits on the whole,while,respiration intensity and ethylene generating rate were inhibited by 1-MCP treatments.With the extension of shelf time,enzyme activity increased with fruit softening including PG,Cx and amylase,which were consistent with the process of fruit senescence and softening,all of the activity of the enzymes aforementioned showed a decrease after the 1-MCP treatment,among which the PG,Cx and endoenzyme in Fiji and Hanfu planted in mountain fruits presented better responses to the inhibition.In the comparison of Hanfu fruits,the Hanfu planted in mountain performed slower speed in softening and senescence,which may be related to the plantation soil and climate status of Moyun Mountain.1-MCP treatment can significantly inhibit the increase of volatile substance content of the fruit,and inhibit the activity of enzymes related to aroma synthesis(LOX,HPL,AAT and PDC).The total ester contents of the Fuji apples were higher than Hanfu apples,and a changing pattern of Hanfu planted in mountain > Hanfu > Fuji fruits in the contents of aldehydes was shown,the total alcohols contents in the CK group of Hanfu planted in mountain were always the champion throughout the period of shelf life,the aroma-related enzyme activity of the Hanfu fruit is higher than that of the mountain Hanfu fruit,which therefore endowed the orchard Hanfu apples rich aromas. |
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