Experimental Study On The Mechanism Of Cell Tissue Damage In Fruits And Vegetables During Storage And Transportation

With the continuous improvement of people's living standards in recent decades,the requirements for the quality of fruits and vegetables have also been continuously improved.In the process of storing fruits and vegetables,temperature load and mechanical load will cause damage to fruits and vegetables.The cooling process of 9 different cooling rates at 1 °C/min,2 °C/min,5 °C/min,8 °C/min,10 °C/min,15 °C/min,20 °C/min,50 °C/min,90 °C/min of fruit and vegetable samples was studied using a low temperature tensile test equipment equipped with a low temperature micro force in-situ loading and observation analysis system.The mechanism of damage to the fruit and vegetable cells caused by the formation of ice crystals in the fruit and vegetable cells during the cooling process,the change of the morphological parameters of the fruit and vegetable cells under temperature load and the mechanism of the damage caused by the stretching of the fruit and vegetable samples in all directions were studied.(1)The formation and distribution of ice crystals in fruits and vegetables and their effects on cell damage were studied experimentally at different cooling rates.The formation and growth of ice crystals in fruit and vegetable cells were obtained by the location of the ice crystals in the fruit and vegetable tissues at different cooling rates and the distribution of three different growth patterns.At the same time,the probability of ice crystal nucleation in fruit and vegetable tissue at different cooling rates was analyzed.The experimental results show that,the cooling process with a cooling rate of 20 °C/min can inhibit the nucleation of ice crystals in fruit and vegetable cells,and effectively reduce the degree of mechanical damage and the chance of mechanical damage.(2)The effects of different temperature loads on the morphological parameters of fruit and vegetable tissue were studied by using typical fruits and vegetables such as radish,apple and potato as research objects.Analysis of the changes in morphological parameters such as freezing temperature,circumference,diameter,area,roundness,deformation,volume and internal pressure of vegetable tissue cells before cooling at different cooling rates,and comprehensive analysis of the optimal cooling rate of various experimental fruit and vegetable cells.The experimental results show that the optimal cooling rate of fruit and vegetable tissue cells varies with different varieties.The optimal cooling rate of radish cells was 20 °C/min,the optimal cooling rate of apple cells was 8 °C/min,and the optimal cooling rate of potato cells was 15 °C/min.(3)The effect of coupling of mechanical load and temperature load on the damage of fruit and vegetable tissues was studied experimentally.Experimental calculation and analysis of mechanical parameters of potato samples under different stretching directions(x,y,z)and different cooling rates(0.5 °C/min,1.2 °C/min and 2 °C/min).The SHEFFE method in the multivariate analysis of SPSS data statistical software was used to analyze the low temperature mechanical properties of fruit and vegetable tissue samples.The experimental results show that,the maximum failure stress values of the potato sample specimens in x,y and z are the largest at 2 °C/min.The mechanical tensile properties of the specimens taken in the z direction are more excellent,which is more related to the average number of cells in this direction.