Effect Of Heat Treatment On Postharvest Quality Of Melon And Study On The Device

Melon(Cucumis melo L.)is one of the main cultivated cash crops in Xinjiang.Its unique flavor,crisp and refreshing taste is loved by consumers at home and abroad.However,the reticulated structure of melon epidermis is easily infected by pathogenic bacteria,which leads to the decay and softening of fruit during postharvest storage and transportation.Although fungicides are effective in controlling postharpostharst melon diseases and softening,their continued use will not only enhance the resistance of pathogens,but also cause potential safety risks to human health and the environment.As an economical,safe and effective method,heat treatment can reduce the microbe on fruit surface and induce resistance to maintain the postharst quality of melon.This paper takes early maturity‘Xizhoumi No.25’,medium maturity ‘Jinmi No.3’ and ‘Jiashi melon’as the test materials,analyzes the quality change rules of melon fruit storage period,compare the difference of heat treatment temperature and time on the quality of different melon fruit storage period,and screen the appropriate heat treatment process parameters;Design a melon heat treatment device that integrates the functions of cleaning,soaking,drying and precise temperature control of fruits and vegetables,and propose a solution to the shortcomings of the equipment,and finally design a heat treatment device that meets the high efficiency and high quality.The main findings are as follows:(1)The technical condition of postharvest heat treatment of melon fruits of different varieties were clarified.The appropriate heat treatment conditions for ‘Xizhoumi No.25’ and ‘Jiashi melon’are 62℃ and 15 s,for ‘Jinmi No.3’,58℃ and 15 s,and the heat tolerance threshold for melon fruit is 58℃.Suitable high temperature and short time heat treatment can delay the decrease of melon fruit hardness and soluble solids and slow down cell membrane damage.(2)The effect of heat treatment on the posterior cell wall metabolism of ‘Xizhoumi No.25’,‘Jinmi No.3’ and ‘Jiashi melon’ fruit was studied.Heat treatment can effectively reduce the decrease of melon fruit hardness and PP.Retarded PME,PG,Cx and β-Glu activity.Correlation Analysis showed that the dissolution and depolymerization of pectin in melon fruit were the main causes of fruit softening.The enzyme that plays the main role of ‘Xizhoumi No.25’ and ‘Jiashi melon’ fruit during the storage period is PME,while the Cx enzyme is the main enzyme of ‘Jinmi No.3’ melon pectin.This may be one of the reasons why the fruit of ‘Jinmi No.3’ are less heat resistant than‘Xizhoumi No.25’ and ‘Jiashi melon’.(3)Designed a melon preservation heat treatment device.It is mainly composed of cleaning,blanching,drying and control devices,and is optimized for problems that arise in practical applications.The optimized melon heat treatment preservation equipment reduces the moisture loss of the peel and pulp by inhibiting the respiration rate and ethylene release rate of the melon fruit,and reduces the mechanical damage of the melon fruit;the melon is bleached within the set time parameters,which effectively reduces the heat shock effect and better maintains the quality of the storage period and shelf life of the melon fruit.Compared with the traditional heat treatment device,the heat treatment technology has the advantages of controllable heat treatment conditions,simple operation and time saving to meet the design requirements.