Research On The Influence Of Whole-process Cold Chain Circulation Technology On Changes In Nutritional Quality Of Yellow Peach,Spinach And Eggplant

With the improvement of people’s living standards,people are increasingly pursuing high-quality fruits and vegetables in their daily lives,and the way people buy fruits and vegetables has changed from the previous few large purchases to many small purchases.Therefore,it is particularly important to keep high-quality fruits and vegetables after harvest.Because fruits and vegetables still have physiological activities such as respiration after harvest,if not treated,it will cause high decay loss rate of fruits and vegetables and bring great economic losses,so the cold chain logistics technology came into being.The whole process of cold chain can reduce the loss of fruits and vegetables during storage and transportation,so that fruits and vegetables still have a good quality when they reach consumers.There are many technical links in the cold chain logistics of fruits and vegetables,and each link is very important.However,the influence of each link in the whole cold chain on the quality change of fruits and vegetables is not clear.In this study,yellow peach,spinach and eggplant were used as test materials,and the effects of the whole cold chain on the nutritional quality of fruits and vegetables were studied,and the links that had the greatest impact on the nutritional quality of fruits and vegetables were identified.The main results were as follows:（1）Study on the effects of different delayed precooling time（0,1,5 and 9 h）on physiological characteristics of spinach.The results showed that due to the influence of field heat and respiratory heat,the longer the delayed pre-cooling time,the higher the temperature,respiratory intensity and ethylene release,and the longer the pre-cooling time of spinach.The temperature of spinach was 23.2,24.3,25.9 and 27.6℃after stacking for 0,1,5 and 9 h,respectively.The respiratory intensity was 261.27,264.55,266.37 and 269.10 mg CO₂/（kg·h）,respectively.The ethylene release rates were 0.84,0.935,0.958 and 1.052 ul/（kg·h）,respectively.Pre-cooling time of differential pressure pre-cooling to 4℃is 30,40,50 and 65 min,respectively.（2）Study on the effect of with or without precooling on the nutritional quality of eggplant.The results showed that compared with that of 25℃circulation,the commodity life of the pre-cooling combined with 25℃circulation was prolonged about 2 days,the sensory evaluation score was 5.5,the retention rate of vitamin C,soluble protein,total phenol and anthocyanin was above 50%,which was 5%-10%higher than that of 25℃circulation.（3）Study on the effects of on the nutritional quality of yellow peach,spinach and eggplant with or without film packaging.The results showed that yellow peach,spinach and eggplant had better nutritional quality after circulation with film packaging.The retention rate of vitamin C,soluble protein,total phenol and other nutrients in yellow peach,spinach and eggplant with film in cold chain was 68%-80%,which was 5%-20%higher than that in cold chain without film circulation.Compared with yellow peach and eggplant under room temperature or higher temperature without film,the commodity life was prolonged above 2 days,the retention rates of vitamin C,soluble protein,total phenol and other nutrients are higher 5%-10%in circulation with film packaging.（4）Study on the effects of whole process cold chain in the nutritional quality of yellow peach,spinach and eggplant.The results showed that compared with normal temperature or high temperature circulation,the nutrition and quality of the whole cold chain circulation were better.The commodity life of yellow peach in cold chain circulation at 4℃was 4 days longer than that at 31℃;After 6 days,the whole cold chain with film had the best nutritional quality,and the sensory evaluation of 7.1,weight loss rate of 2.59%and hardness of 60.81 N in yellow peach;The nutrient contents of soluble solid,vitamin C,soluble protein and total phenol were 6.99%,1.87mg/100g,3.62 mg/100g and 0.51 OD₂₈₀/g,respectively.The retention rate of nutrient content was more than 77%,20%-30%higher than that of circulating at31℃.After cold chain circulation of spinach at 4℃for 6 days,delayed precooling for0 h had the best nutrition and quality.The sensory evaluation score was 7.2,the weight loss rate was 4.25%,the contents of vitamin C,chlorophyll and soluble protein were4.66 mg/100g,0.73 mg/g and 0.35 mg/g,respectively,and the retention rate of nutritional content was more than 74%.Compared with the whole cold chain circulation of eggplant at 12℃,the commodity life was prolonged above 6 days circulating at 25℃.After 6 d,the sensory evaluation score was 7.5,the weight loss rate was 0.50%,firmness was 24.5 N,and the content of vitamin C,soluble protein,total phenol and anthocyanin were 1.34 mg/100g,23.04 mg/100g,4.01 D₂₈₀/g and 3.43(OD₅₃₀-OD₆₀₀)/g respectively.The retention rate of nutrient content was more than 77%,which was higher 20%～50%than that of circulating at 25℃.The carbon emission of the whole cold chain film packaging circulation for 6 days was 376.73 g CO₂/kg,and the minimum unit carbon emission was 62.78 g CO₂/kg/d.（5）For the analysis of the changes of nutritional quality of yellow peach,spinach and eggplant,the results demonstrated that the weight loss rate,VC and total phenol content had the most changes in the pre-cooling link,the most change of the soluble protein was observed in refrigeration link throughout the whole cold chain with film packaging.The most changes of weight loss rate,VC and chlorophyll content of spinach was inhibited in the sales link.Overall,considering the effect of delayed precooling on spinach and with or without precooling in eggplant,precooling has the greatest influence on the nutritional quality of fruits and vegetables,but other links of the whole cold chain can not be ignored in practical application.