The Effects Of Ultraviolet Sterilization On Quality Of Kiwifruit Juice

There existed a sterilization process in kiwi-fruit juice processing. Heat sterilization likehigh-temperature short-time sterilizing and pasteurization is the main sterilization methodcurrently, which causes great destruction to the nutrition in kiwifruit juice, especially to Vc.This paper is aimed to study ultraviolet sterilization effect on kiwifruit juice and exploreultraviolet sterilization’s influence on the nutrition, enzyme activity, aroma components inkiwi-fruit juice through non-thermal sterilization, and provide theory foundation tonon-thermal sterilization’s application on food industry. This paper has the followingconclusions:（1）Response experiment optimized the best condition of ultraviolet sterilization underthe UV lamp of40W: thickness of kiwi-fruit juice0.81mm, irradiation distance8cm,irradiation time53.67min and fruit juice temperature16℃. At this condition, sterilization rateof E. coli,molds and yeasts can reach100%.（2）Activity of PPO in kiwifruit juice decreased15%under the best ultravioletsterilization condition, but activity of POD,CAT,SOD have little change after ultravioletsterilization; Activity of PPO in kiwifruit juice decreased48.65%after heat sterilization,almost all the POD are inactivated, but activity of SOD,CAT stay stable. Ultravioletsterilization causes less obvious effect on enzyme activity in kiwifruit juice than heatsterilization.（3）Heat sterilization destroyed nutrition heavily, which had harmful effect on qualityof kiwifruit juice. Heat sterilization decreased58.5%acidic substances,53.31%Vc and63.01%chlorophyll in kiwifruit juice, and caused juice quality deteriorated obviously;Ultraviolet sterilization can keep contents of soluble solids, acidic substances, Vc andchlorophyll steady. Retention rate of reached97.6%,95.3%,72.7%,68.2%separately. Soquality of kiwifruit juice has little change after ultraviolet sterilization.（4）Heat sterilization caused great destruction to aroma components in kiwi-fruit juice.After heat sterilization, aroma components reduced71.23%and ethyl acetate disappeared,which make the aroma faded; Ultraviolet sterilization can keep the aroma components andcontents better. Though the content of aroma components decreased50.95%, the aroma in kiwifruit juice is stronger than the juice by heat sterilization. Retention rate of the main aromacomponents butyrate,2-hexenal, hexanal and ethyl acetate in kiwifruit juice is higher.Ultraviolet sterilization effect is better than heat sterilization, which is an efficientnon-thermal sterilization of juice. It is more Environmental, clear and energy saving than heatsterilization and can be applied in juice process industry.