The Effects Of Heat Treatment And Different Biological Preservative Coatings On Preservation Of "Hosui" Pear Fruits

In the present work,the effects of heat treatment,film-processing of lysozyme with different contents,and biological preservative film with chitosan or konjacmannan treatments on nutritional qualities such as weight-loss rates,rotten rates,hardness,titratable acid contents,V_C and sugar contents etc,respiration rate, fruit membrane permeability,MDA content,SOD,POD,and CAT activities in hosui pear fruits were investigated during fruit storage with the aim to provide theoretical and practical basis for post-harvest storage and preservation of hosui pears. The results showed as follows:Heat-water treatment followed with cold storage had influences on some physiological indexes and intrinsic quality changes.Furthermore,the heat-treatment at appropriate temperature could significantly inhibit the respiration rate of the fruits, preferably maintain their quality,reduce the permeability of cell membranes, maintain a relatively high activities of SOD and CAT,delay their hardness-declining and maturation process and prolong the period of storage.The results showed that the heat-treatment at 45℃water for 30 minutes had the best effects on fruit storage.The influences of lysozyme coating with different contents on physiological indicators,nutritional composition quality and protective enzyme activities in hosui pear fruits were investigated.The results showed that,at postharvest 20days, lysozyme coating treatments could significantly reduce the rates of fruits loss,rotten fruits and respiration with the average lower than the control respectively 35 percent, 19.8 percent and 12.2 percent.Lysozyme coating treatments could effectively retain the internal fruit quality that fruit hardness and V_C content were higher than the control 0.47 kg/cm~2 and 0.35 mg/100g respectively.FW,titratable acid and sugar content were 6.6 percent and 9.8 percent respectively higher than the control. Lysozyme coating treatments could inhibit the increase of fruits membrane permeability and MDA contents,remarkably restrain the decrease of SOD and CAT activities.After storaging for 20 days,SOD,CAT activity were higher than the control respectively 57.1 percent and 37.1 percent on average.Furthermore,the effect of 0.05%concentration lysozyme coating was the best among the three treatments.The results showed that 2%chitosan coating could significantly reduce the rates of rotten fruits and respiration,delay the hardness of fruits and the declining rate of titratable acid,V_C and reductive sugar contents and effectively improve the influence of fruit storage;the 2%0 konjacmannan coating could significantly inhibit the increasing of weight-loss rates and show better preservation performance;the mixed coating of 2%chitosan and 2%0 konjacmannan accelerated the fruits' rotten rates, changed the internal quality and quickened their maturation and senescence process.