Effect Of Chitosan Coating On Quality,Antioxidant Capacity And Microbial Contamination Of Fresh-cut Hami Melons

Hami melon is a typical fruit in Northwest of China,however,the ediblerate of fruit is quite lower,with only 60% weight of total fruit.As a longer distance between the production and consumption areas,the logistics cost of fruit is quite high,it is necessary to develop a new postharvest handling technology of keeping quality and lowing cost of Hami melon.In this study,the cultivar ‘cv.Xizhoumi' of Hami melon was used material.The fruit was cut into cubers,treated with 2% of chitosan,then put into plastic containers.The quality,antioxidant capacity and microbial contamination of fresh-cut fruit were regularly determined.The results showed that:1.Chitosan coating effectively reduced weight loss,maintained the firmnessof fresh-cut fruit.After 12 days of treatment,the weight loss of treated fruit was 24.1% lower than the control,the firmness is was 13.3% higher than the control.The treatment significantly maintained the color,and the content of total soluble solids?TSS?and titratable acid?TA?of fresh-cut fruit.After 12 days of treatment,the value of L*,a*and b*of treated fruit was 4.3%,24.3% and 13.3% higher than the control,TSS content was 6.9% higher,and TA content was 35.2% lower than the control.2.Thecoating effectively maintained sensory quality of fresh-cut fruit.After 9 days of treatemnt,the treated fruit showed better taste,aroma and decay than the control,the cubers werefree fromdecay,thequality closed to the harvested one.After 12 days of treatement,although the treated fruit had higherscore of color,taste,aroma and decay,however,the cubers beganto rot,the quality breakdowned,edible value losted.Therefore,9 days and 6 days are the maximumshelf-life of treated and the control of fresh-cut Hami melon,respectively.3.Chitosan effectively delayed the peak H₂O₂ production,and decreased H₂O₂ content of fresh-cut fruit.The treatment also maintained the content of Vc,total phenolics and flavonoid,after 12 days,the treatment was 18.1%,28.9% and 83.1% higher than the control,increased the activity of superoxide dismutase?SOD?and catalase?CAT?,inhibited the activity of ascorbate peroxidase?APX?,peroxidase?POD?and polyphenol oxidase?PPO?.The treated fruit had a higher capcity of DPPH and ABTS +.radical scavenging than the control,after 9 days,the treatment was 41.5% and 51.9% higher than the control.4.The coating significantly inhibited the growth of aerobic plate count,yeasts,molds and coliforms on cubersurface.The four microbial indicators increasd rapidlyin the control after 6 day of frush-cut,however,the treated fruit began to increaseslowly after 9 days.The quantity of aerobic plate count,yeasts,molds and coliformsin treated fruit was only 1/5,1/9,1/5 and 1/9 of the control after 12 days of treatment.No Salmonella,Staphylococcus aureus and Listeria wasdetectedin treated and the control fruit during storage.In conclusion,the chitosan coating maximumly maintainsthe quality of fresh-cut Hami melon ‘cv.Xizhoumi',enhance the antioxidant capacity of the cubers,inhibits the growth of aerobic plate count,yeasts,molds and coliforms.Sensory evaluation indicats that chitosan coating prolongs the shelf-life for 3 days of fresh-cut fruit.