Experimental Study On Optimum Process And Water Migration Of Shenzhou Peach During Ice-Temperature Storage

In this paper,the effects of precooling after harvest,cold acclimation before ice temperature storage and ice temperature storage on the quality,fractal structure and water transfer characteristics of shenzhou peach were studied.This paper conducts research from the following three aspects.Firstly,the changes of life quality of peach during storage were analyzed by testing the life indexes.Secondly,based on the fractal theory and the characteristics of porous media,the fractal structure parameters of peach which includes porosity,pore fractal dimension,mean tortuosity and tortuosity fractal dimensions were analyzed.Finally,the changes of water content and water state which includes free water,bound water and immobile water during storage were measured,and combining the weightlessness rate,relative electric conductivity and parameters to analyze the correlation between the parameters.The mechanism of cold acclimation process to prevent chilling injury of shenzhou honey peach and improve the quality of ice temperature storage was obtained,the necessity of precooling and cold acclimation process before ice temperature storage was explored,and the reasonable technological parameters of precooling,cold acclimation and ice temperature storage were obtained.The conclusion can provide basic data and theoretical guidance for follow-up fruit and vegetable storage research,and promote the wide application of ice temperature preservation technology.The research results show that:Ice temperature storage reduced the weightlessness rate of peach,reduced the respiration intensity of peach,inhibited the decomposition of soluble solids,reduced the damage of cell membrane system during storage,and reduced the accumulation of MDA.POD and CAT enzyme activities showed that freezing temperature storage could delay the aging of nectarine and maintain the quality of nectarine,and the shelf life of freezing temperature storage was about 40 days longer than normal storage.Ice temperature storage can effectively reduce the water loss rate of nectarine due to changes in the pore structure of nectarine.The low temperature acclimation treatment can maintain the porosity of peach tissue well,and the simple precooling treatment enhances the increase of porosity to some extent.Low temperature acclimation treatment effectively maintains the uniformity of pore structure of fruit and vegetable tissues.Domestication treatment inhibited the reduction of the tortuous fractal dimension of peach tissue.After pre-cooling and before storage at freezing temperature,the peach was induced at low temperature,and the water flow resistance was increased by reducing the porosity of the peach tissue and increasing the complexity of the pore distribution,so as to inhibit the water loss and delay the aging of the peach,thus effectively maintaining the quality of the peach.The porosity and fractal dimension of deep state peach increased with the storage time,and the mean tortuosity and the fractal dimension of tortuosity decreased with the storage time.During the whole storage period,the fractal parameters at the epidermis and nucleus changed little,while those at 2/3r changed greatly.The curves of porosity and fractal dimension of pores at different radii of the same peach were concave,and the surface and core had larger porosity and fractal dimension.The curve of mean tortuosity and tortuosity fractal dimension at different radii of the same peach showed"convex"shape,and the mean tortuosity and tortuosity fractal dimension at 1/3r and 2/3r were larger.The water content of peach decreased with the increase of storage time.At the end of storage,the water content of each group decreased by about 20.5%_-ZJIC?24.2%_-YZIC?11.3%_-YKICYKIC and 6.8%_-YMIC,respectively,compared with that at the beginning of storage.During the whole storage period,the water loss rate of the control group was the highest,followed by direct ice temperature storage after precooling.Low temperature domestication combined with precooling treatment could reduce the water loss of honey peach,and the increase of precooling treatment on the basis of ice temperature storage would increase the water loss of peach.