Effects Of Cuticular Wax Changes On Physiological Quality Of Apple During Storage

Apple is one of the most important bulk fruits in the world and has high nutritional value.In the post-harvest storage and preservation process,the wax of apple cuticular plays a vital role in fruit quality.In this research,ten varieties of apple,"Stark","Golden ","Mutsu","Golden Deliciouse","Camachi"," Hua Hong "," Jona Gold "," Red Star "," Ralls " and " Mishima Fuji " were tested at room temperature as materials.The weight loss rate,firmness,respiration rate,and ethylene release rate were examined to analyze the differences in storage properties.Then scanning electron microscopy and gas chromatography-mass spectrometry were used to observe and analyze the microstructure and material composition of apple cuticular wax.The clustering analysis and correlation analysis were used to determine the changes in the wax content of the apple cuticular,the relationship between changes in components and changes in fruit storage quality and related physiological indicators.Variation of main components of waxy "Stark","Golden Deliciouse","Red Star" and "Huahong" were tested under low temperature storage conditions.Provide a scientific basis for the connection between apple cuticular wax and storage,And establish the theoretical foundation for changing gene or coating to change the wax composition to extend the storage time of apples.The main research results are as follows:(1)There are differences in physiological indicators between different varieties of apples.After the overall evaluation of principal component analysis,we can see that "Ralls","Mishima Fuji","Stark","Mutsu" and "Hua Hong" have better storability;"Jona gold","Golden","Camachi","Golden Deliciouse" and "Red Star" have poor storage.There are differences in the waxy structure of different apple varieties.The skins of fresh fruits after picking differ greatly.After storage,the waxy crystal structure is similar.During the storage process,all varieties,except "Camachi",has became greasy.But the wax of fresh "Camachi" cuticular has already changed,which was different from other varieties.(2)During storage,the ultra-morphology of the apple cuticular wax dynamically changed.The microstructure of the apple cuticular wax changed,and a fusion phenomenon has occurred.The flake-like,filament-like and rod-like crystal structures are finally fused into a smooth waxy structure or an irregular crystal structure.(3)The wax of apple cuticular decreased significantly after storage.After storage,the wax content of the ten varieties changed,and their proportions also changed.The content of alkanes and alcohols decreased,and fatty acids,aldehydes and terpenes increased.It was found that the composition of waxy components of fresh "Red Star" apples was different from that of other varieties,and was similar to that of other varieties of apples after storage.It was found that the content of waxy components of fresh "Golden Deliciouse" apples was quite different from other varieties.It is found that the correlation coefficient between the weight loss rate of fruits and the content of alkane substances and the total amount of waxy matter is higher than 0.8,while the alkane content found in the "Red Star" apple is the lowest,and the water loss rate during storage It is high and has poor storability.It is concluded that the waxiness of apple epidermis,especially its alkane component,may be of great significance in preventing water loss during storage of apples.(4)During the low-temperature storage,the wax content increased first and then decreased,and the low-temperature can reduce the epidermal wax content.During storage,the wax content of the apple epidermis and the content of alkane substances increased first and then decreased;the contents of alcohols continued to decrease;the content of fatty acids continued to increase.During storage,the "Red Star" wax content was lower than other varieties,and reached the peak of wax content on the 30 th day,which was earlier than other varieties.