Effects Of Different Storage Methods On Fruit Quality Of Raspberry

ObjectiveThe fruit tissue of raspberry is delicate and the peels is very thin,the structure of raspberry is easily fragile and it’s hard to be storage,especially in the process of transportation,raspberry is easily to be damaged by mechanics and microbial infection.Stored in normal temperature for 1 day,the tissue will be softened and a large amount of juice will flow out.Stored in low temperature conditions(4℃)for 1 day,the same situation will appear and the raspberry will lose its commercial value.Therefore,it’s important to make raspberry stored fresh.This paper mainly studies the stored problem of raspberry and try to find the influence of different frozen storage time and different storage methods on the quality of raspberry.The author aims to finding a good method of storage raspberry and to slow down the speed of deterioration of raspberry.MethodsThe Experiment took raspberry as the raw material,by using high performance liquid chromatography(HPLC)to test Polyphenols,anthocyanins,VC content of the four varieties of raspberry(Heritage,Qiufu Autumn Bliss,Fertod Zamatos,Meeker)in different time of cold storage.In the mean time,the physical and chemical indexes of antioxidant activity and the activity of enzymes that affect the occurrence of softening and deterioration were also determined.Chitosan was used as the matrix,and different concentrations of natamycincomposite coating were added.The sensory quality and physiological and biochemical indexes were determined during the storage and preservation of raspberry.Relative humidity(%),O2 volume fraction(%)and CO2 volume fraction(%)were selected as the object of study.The decay index(%)was used as the evaluation index,and the response was analyzed by using the single factor experiment.Surface method to study the various variables and their interactions in the fresh and healthy raspberry condition,to optimize the storage conditions of the atmosphere and to prolong the shelf life of the raspberry.Results1.In the frozen process of four different varieties of raspberry,the raspberries which were frozen for 3 months compared with the fresh raspberries,there were no significant changes in the nutritional indexes and enzyme activities.After 12 months of freezing treatment under the condition of freezing at-18,the content of total phenolics in raspberry did not change significantly,only the ellagic acid content decreased.During the process of storage Vitamin C and titratable acid content decreased,malondialdehyde(MDA)content increased continuously,and anthocyanin content increased in the first three months,then decreased gradually.Polyphenol(PPO),peroxidase(POD),pectinase and cellulase activity oxidase in Raspberry were increased first and then decreased within the frozen for 12 months.2.The treatment of chitosan and natamycin combined coating had a significant effect on the quality of postharvest raspberry fruit,which could reduce the decay index of fruit during fruit preservation,soluble solids of raspberry fruit,high content of titratable acid and vitamin C.In the control,to maintain fruit quality,extend the shelf life has a significant effect.After treatment,the antioxidant ability of the fruit was improved,and the content of the phenolic compound and the activity of SOD,PPO and POD were increased,and the content of malondialdehyde(MDA)was inhibited and the disease resistancewas enhanced.By measuring the concentration of the coating film,the most suitable extension of the raspberry shelf life of the coating dose,6 groups of trials,1% chitosan and 0.020% natamycin composite coating treatment of raspberry fruit Quality of the best preservation effect.3.The optimum conditions of storage and preservation of raspberry by the response surface method were 81.62%,and the relative humidity was 81.62%.The optimum conditions were as follows: the relative humidity was 81.62%Volume fraction of 23.36%,O2 volume fraction of 6.51%.Under these conditions,raspberry storage 7 days when the decay index was the lowest,20.51%.Conclusions1.The results shows that the raspberries which were frozen for 3 months compared with the fresh raspberries,there were no significant changes in the nutritional indexes and enzyme activities.After 12 months of freezing treatment under the condition of freezing at-18,the content of total phenolics in raspberry did not change significantly,only the ellagic acid content decreased.During the process of storage Vitamin C and titratable acid content decreased,malondialdehyde(MDA)content increased continuously,and anthocyanin content increased in the first three months,then decreased gradually.Polyphenol(PPO),peroxidase(POD),pectinase and cellulase activity oxidase in Raspberry were increased first and then decreased within the frozen for 12 months.Frozen maximizes the color,aroma and texture of the raspberry,and the thawed fruit is substantially close to the fresh raspberry.So it has plenty of time to provide raw materials to processing factory as well as transportation and sales.And it can provide a theoretical reference for the production of raspberry fruit processing products.2.The effect of chitosan and natamycin on the quality of postharvest raspberry fruit was significant.By comparing the experimental results with 1%chitosan and 0.020% natamycin composite coating,Fruit quality of the best preservation effect.3.The optimal conditions of the storage of raspberry were 81.62%,the volume fraction of CO2 was 23.36% and the volume fraction of O2 was 6.51%.Under these conditions,raspberry storage 7 days when the decay index was the lowest,20.51%.Coating and aerial storage provide a technical reference for extending the shelf life of raspberry.