| Cantaloupe,mainly produced in Xinjiang Province,is an important cash crop,which is rich in vitamins,sugar and other nutrients,and is deeply welcomed by consumers for its unique flavor.However,as cantaloupe is a kind of climacteric fruit and harvested optimally in hot summer,improper storage after harvesting will lead to a decline in the quality of cantaloupes,which brings serious economic losses.Therefore,it is extremely important to find an economical,environmentally friendly and harmless storage method to maintain the postharvest quality of cantaloupes.Ultraviolet-C（UV-C）irradiation has strong bactericidal property,which can enhance the resistance of postharvest stress,thereby reducing postharvest loss and prolonging the storage life of fruit and vegetables.Chitosan（CH）could be coated on the surface of fruits to slow the respiration and transpiration of fruits,thus delaying aging.In this thesis,the effects of combined UV-C and CH processing on postharvest physiology,antioxidant activity and softening of cantaloupes were studied using Cantaloupe“Xizhoumi 17”as experimental material,and the feasibility and advantages of combined UV-C and CH processing on storage and preservation techniques of cantaloupes were discussed,so as to provide theoretical basis for the development and application of storage and preservation techniques of cantaloupes.The results are as follows:（1）Effects of combined UV-C and CH processing on postharvest quality of cantaloupe during storageThe effects of UV-C irradiation（with dose of 4 k J/m2）and CH（with concentration of 1%）combined processing on the postharvest quality of cantaloupe during storage were studied,the results of which showed that at the end of storage,the fruit firmness,soluble solid content and titratable acid content of cantaloupes subjected to combined UV-C and CH processing were 1.13 times,1.14 times and 1.35 times of those of the control group,respectively.In addition,combined UV-C and CH processing decreased the decay rate and weight loss rate,delayed the increase of respiration intensity and ethylene release rate,and inhibited the increase of relative electrical conductivity and MDA content of cantaloupes.To sum up,the storage quality of cantaloupe was maintained well through combined UV-C and CH processing.（2）Effects of combined UV-C and CH processing on antioxidant activity of cantaloupe during storageCombined UV-C and CH processing reduced the loss of ascorbic acid in cantaloupe.At the end of storage,the contents of ascorbic acid,total phenol and flavonoids in the combined treatment group were23.40%,32.51%and 72.90%higher than those in the control group,respectively.In addition,combined UV-C and CH processing maintained high SOD,CAT,APX and POD activities during storage,and inhibited the increase of O2production rate and H2O2content in cantaloupe.By enhancing the antioxidant capacity of cantaloupe,combined UV-C and CH processing effectively inhibited the increase of reactive oxygen species,thereby reducing the damage of reactive oxygen species to cell membrane.（3）Effects of combined UV-C and CH processing on soften of cantaloupe during storageThe combination of UV-C and CH delayed the degradation of cell wall components and inhibited the activity of cell wall degrading enzymes.It was found that on the 49th day of storage,the higher content of protopectin and cellulose was maintained in the combined processing group,which was 1.84 times and 1.74times higher than that the control group,respectively,and the increase of soluble pectin content was inhibited,only 70.48%of the control group.In addition,the combined processing inhibited the increase of the activity of cell wall degrading enzymes（PG,PME,Cx,β-Glu,β-Gal）,and delayed the peak time of cell wall degrading enzymes.In conclusion,combined UV-C and CH processing could delay the softening of cantaloupe and maintain its storage quality. |
