Postharvest Quality Evaluation And Temperature Adaptability Of Kiwifruit

The kiwifruit has a high nutritional value,a delicious taste,a wide variety of species,a significant variation in quality between types,a typical respiratory leap fruit,thin skin,fast ripening,sensitivity to the environment,a short shelf life at room temperature,and not easy to store and transport.Low-temperature refrigerated transport is the most common method used.Still,the process produces temperature fluctuations that accelerate the deterioration of kiwifruit quality and seriously affect the commercial value of kiwifruit.In this thesis,the quality of different varieties of kiwifruit was tested for a comprehensive quality evaluation.Two kiwifruit species(Hongyang and Xuxiang)were selected for the study and subjected to temperature fluctuations to investigate the effect of temperature fluctuations on the quality of different kiwifruit varieties.The main findings were as follows.(1)The fruit quality of 12 kiwifruit varieties was studied,and it was found that the sensory quality and anti-oxidant of kiwifruit varied significantly,as well as the polyphenol and carotenoid fractions and contents,among the different varieties.A comprehensive evaluation of kiwifruit quality was performed using principal component analysis,with a cumulative contribution of 68.609% for the four principal component factors,reflecting most of the information on the functional nutritional quality of kiwifruit.The variety with the highest overall value was Xu Xiang.(2)During the storage of kiwifruit,temperature fluctuations had a greater impact on the quality of kiwifruit in the pre-storage period,accelerating the decline in hardness and vitamin C,increasing the soluble solids content,and causing the decay of kiwifruit quality parameters in all aspects,leading to an overall decay phenomenon.And the greater the temperature fluctuation,the greater the impact on the quality of kiwifruit,which is not conducive to the preservation of kiwifruit.(3)Temperature fluctuations significantly reduced the quality of the shelf kiwifruit fruit,accelerated the ripening and aging of the shelf kiwifruit,and increased the weight loss,morbidity,soluble solids content and transparency of the kiwifruit fruit during the shelf life.Differences in the size of temperature fluctuations had a significant impact on the deterioration of kiwifruit quality,with the greater the fluctuations,the more rapid the decline in kiwifruit quality.(4)Temperature fluctuations increased the degree of fruit hyalinization and aggravated the decrease in carotenoid and chlorophyll content.The greater the temperature fluctuation,the more severe the degree of fruit hyalinization.Meanwhile,enhanced relative conductivity promoted the gene expression of polygalacturonase(PG),β-galacturonase(β-CAL),and pectin methyl esterase(PE).In addition,ultrastructural results showed that Temperature fluctuations destroy the morphology and cell structure of the cell walls.Kiwifruit accelerates the post-ripening process in low temperature conditions with fluctuating temperatures,reducing the eating quality of kiwifruit.