Effects Of Irradiation And Temperature On The Storage And Transportation Effects Of Chestnuts At Different Stages After Harvesting And Shelf Life Prediction

Chestnut is a nut fruit.Although protected by a hard shell,its structure and respiratory intensity make it difficult to store and lose nutrients quickly.Chestnut will cause water vapor condensation because of high respiratory intensity during storage,therefore,this experiment studied the best PE/PA bag punching specification for the sub sequent experiment of fresh storage of chestnuts.According to the different physiological activities in different periods after picking,the storage time of chestnut can be divided into three stages:harvest period,dormant period and germination stage.At each stage,chestnut was stored after irradiation to determine the optimal radiation dose,and then stored at low temperature and normal temperature after static storage and simulated transport experiments with optimal irradiation dose respectively,The optimal irradiation dose obtained during dormancy was used to keep fresh,the decay rate as the index,the shelf-life prediction model was established to predict the chestnut storage time and verify the fresh-keeping method.The results of this experiment are as follows:1.The punching diameters of packaging bags are 2.5 mm,3.5 mm,and 4.5 mm respectively,and the number of punching holes are 6 holes/bag and 9 holes/bag respectively.Qianxi chestnut as the experimental object,the chestnut was packed in a perforated bag and stored at 25℃ for 20 days.The changes of physical and chemical indexes of chestnut during storage found that the drilling method with 3.5mm and 6 holes had lower decay rate,could better control the weight loss and had better effect on maintaining the quality,so the drilling specification was selected for follow-up experiment.2.Five radiation doses of 0.2 kGy,0.4 kGy,0.6 kGy,0.8 kGy and 1 kGy were used to treat chestnuts at three stages.The optimal radiation dose of chestnuts at each stage was obtained according to the changes of the indicators in storage.The simulated transport experiment was carried out with the optimal irradiation dose,and the simulated transport parameter is 12 h 180 r/min.stored at low and room temperature respectively,to observe the changes of physical and chemical indexes of chestnut at different temperatures during storage.The best irradiation dose of chestnut stored at room temperature during harvest period is 0.8 kGy.Irradiation can reduce the decay rate of chestnut during storage and maintain the nutrients of chestnut.Through the simulated transportation experiment,the quality of chestnut stored at low temperature is obviously better than that stored at room temperature;but for the fresh-keeping effect of irradiation,Irradiation treatment at room temperature can better control the quality of Chinese chestnut,but the effect of irradiation is not obvious during low temperature storage,and transportation and irradiation may aggravate chestnut water loss.The best irradiation dose of chestnut stored at room temperature during dormancy period is 0.2 kGy.In this period,the physiological activity of chestnut was lower,the quality of chestnut changed little,and the fresh-keeping effect of 0.2 kGy was better.According to the simulated transport experiment,the physiological activities of chestnuts in the resting period were lower under each treatment,and the quality of chestnuts was better than that in the storage period of harvesting and germination,which was the stage with the smallest decay in the whole storage period.The best irradiation dose of chestnut stored at room temperature during germination is 0.6 kGy.The experimental results of static storage and simulated transportation show that the decay rate of chestnut stored at room temperature was nearly twice as high as that stored at low temperature in the same period.Irradiation has a better fresh-keeping effect.And it also has a good restraining effect on the quality change caused by transportation,this effect is more obvious under low temperature storage than at room temperature.3.Taking the dormant period of chestnut as the experimental research object,study on Prediction Model of Shelf Life of chestnut by static Storage and simulated Transportation experiment,the shelf life prediction model of the four treatment groups can be established by using the zero order reaction of decay rate.The shelf life prediction models of static control group,static treatment group,transport control group and transport treatment group are respectively:SL腐=|A腐|/e17.34e-43494.69/RT、SL腐=|A腐|/e20.80-51951.4/RT、SL腐=|A腐|e21.38e-5350.58/RT.The predicted results of shelf life of Chinese chestnut show that transportation has little effect on the quality under low temperature storage,irradiation has a good fresh-keeping effect and effectively prolong the storage time.However,with the increase of temperature,the effect of irradiation on chestnut decreased gradually.