Production Of Logistics Fresh-keeping Device Based On Dry Ice And Its Application In Fruits And Vegetables

Dry ice,as an excellent condensing agent and non-toxic,pollution-free chemical raw material,has a very broad application prospect in the logistics and transportation of fruits and vegetables.Dry ice will absorb a large amount of heat in sublimation,and its cooling effect is far superior to the heat absorbed by liquid nitrogen vaporization.The CO2 produced by dry ice can inhibit the consumption of fruit and vegetable respiration,and the large amount of gas produced by it can play a buffer effect on fruits and vegetables and reduce the damage to fruits and vegetables.As dry ice has these excellent characteristics,this paper exploreed the nature of dry ice and optimized the production process of dry ice buffer device,and designed a more reasonable drying process for dry ice buffer.The dry ice fresh-keeping device was applied to Chinese chives and snow pear.The results of the studywere as follows:1.The heat absorbed in the sublimation of dry ice could quickly reduce the temperature in the foam box.Compared with the foam box in the cold storage;the temperature of the foam box with the amount of 250 g was reduced by 55 min at the temperature of 6.When 1g dry ice sublimated,310 mL CO2 gas could be produced,and the gas composition in the closed environment were changed greatly.2.This paper has designed a dry ice buffer device,which was divided into two parts of PE bag for heat sealing,one part for fruit and vegetable placement layer and the other part of dry ice layer.There was a certain distance between the two.The suitable fruit and vegetable and 5 g dry ice were placed in the PE bag and sealed,then sealed in the foam box.3.The results showed that the quality of garlic sprouts during storage decreased with vibration treatment.Among them,when the most vibrant treatment group 3 was stored to sixteenth D,the respiration rate increased by 2.03 times compared to the untreated garlic bolt,the content of soluble solids was 89.66%of the control group,the content of peroxidase increased by 1.88 times,the content of superoxide dismutase increased 1.33 times,and the activity of catalase increased 1.88 times,the content of malondialdehyde increased by 1.07 times,and the conductivity increased by 1.09 times.The study also showed that the tolerance of garlic sprouts to vibration treatment varied,and the speed of its quality decline was:the treatment group 3>treated group 2>treated group 1>untreated group.Among them,the treatment group 3 with the largest vibration amplitude made the quality of garlic sprouts seriously decreased(p<0.05).4.In the study of the influence mechanism of dry ice in inhibiting the quality of Chinese chives and snowflake pear,it was found that the CO2 produced by dry ice inhibited the respiration of the Chinese chives and snow pear,and made the cell membrane lipid oxidation process of the Chinese chives effectively suppressed.The integrity of the cell membrane of the Chinese chives and snow pear was greatly improved and the content of malondialdehyde was inhibited.The process of aging and death of cells was delayed.5.The study on the effect of dry ice on the vibration damage of Chinese chives and snow pear showed that dry ice could inhibit the activity of lipid oxidation related enzymes in plant cell membrane.The superoxide anion generation rate,superoxide dismutase(SOD)activity,catalase(CAT)activity and peroxidase(POD)activity of the Chinese chivess and snowflake pears,which were treated with dry ice,were significantly decreased compared to the vibration treatment group without dry ice.6.Dry ice could also reduce the activity of polyphenol oxidase(PPO)in Chinese chives and snowflakes,thus inhibiting the enzymatic browning process of Chinese chives and snowflakes.