Ultra-high Pressure Sterilization Treatment Of Kiwi Fruit NFC Juice And Its Quality Changes During Storage

Kiwi is a kind of fruit integrated with delicious tastes and rich nutrition.However,being a climacteric berry,kiwifruit highly susceptible to corruption during storage and transportation,affecting fruit quality and economic value.So,there is a broad prospect for the development and research of processed products of kiwifruit.There are abundant resources of kiwifruit with 59 native species in China,many kinds of cultivars.But the processing technology of kiwifruit is still in the initial development stage.At present,the industrialization development of kiwifruit products was limited by some problems of kiwifruit processing,such as imperfect technology,nutrient loss,high production cost and so on.Therefore,it is essential to optimize the processing technology,prolong the storage life,discuss the different processing methods on the quality of kiwifruit products,meet the consumers needs and improve the exploitation and utilization of kiwifruit resources.In this paper,self-made kiwifruit NFC juice was prepared using Hayward kiwi fruit as raw materals.Firstly,the indexes of NFC juice from Hayward kiwi fruit were analyzed.Then the ultra high pressure pasteurisation conditions of kiwifruit NFC juice were optimized by single factor and orthogonal test.Secondly,the changes of nutrition,physicochemical,microbial and antioxidant characteristic of kiwifruit NFC fruit juice with ultra high pressure treatment during storage period were investigated.Finally,the changes of aroma substances of NFC juice after ultra high pressure treatment during storage period were studied.The main experimental results are as follows:1.The microbial indicators analysis results of self-made kiwifruit NFC juice were as follows:the total number of colonies was 2.74 ±0.07 1g CFU/mL,and the number of fungal yeast was 3.37 ±0.061 g CFU/mL,the Escherichia coli was not detected.Physical and chemical indicators analysis results were as follows:pH 3.53±0.03,soluble solid 11.30 ±0.03 Brixs,L value of color 37.96 ±0.24,a value 2.82±0.03,b value 6.30 ±0.16;Nutrition indexes analysis results were:total acid 1.21±0.03 g/L,total sugar 14.54 ±0.15 g/100g,Vc 106.98 ±2.36 mg/100g;Antioxidant activity index analysis results were:DPPH and ABTS free radical scavenging rate of 78.18±0.03%and 89.40 ±0.04%respectively.2.The ultra high pressure pasteurisation conditions were optimized by single factor and orthogonal test,and the optimal germicidal conditions were determined.They were 400 MPa,15 min and twice cycle at normal temperature of 20 ?.3.The changes of microbial,physicochemical,nutritional and antioxidation characteristic of kiwifruit NFC juice with ultra high pressure treatment during storage was investigated using heat treatment(95 ?,30 s)as the control.The results showed that the total number of colony and mold yeast of kiwifruit NFC fruit juice treated by ultra high pressure which exceeded the standard at the fourth week during storage time,Escherichia coli were not detected,while the bacteria appeared in the juice treated by heat treatment at the fourth week,but not exceed the standard,mold yeast and Escherichia coli were not detected.With the prolongation of storage time,the pH value of kiwifruit NFC juice decreased slightly after the two pasteurisation treatments,while the soluble solids remained unchanged basically.The color value of L decreased,the value of a and b gradually increased,the content of Vc decreased of 14.89%,the total acid increased slightly,and the total sugar content increased of 16.03%,the scavenging rate of DPPH free radical and ABTS radical decreased during kiwifruit NFC juice storage period.4.The study on aroma components found that the relative contents of alcohol,aldehydes,ketones and esters in untreated kiwifruit NFC juice were 9.88%,8.35%,4.71%and 2.62%,respectively.After ultra-high pressure pasteurisation,the type and content of alcohols in the juice decreased(4.75%),the types of esters increased,the content(2.53%)decreased;the types and contents of aldehydes(27.38%)increased,and the types of ketones Decrease,the content(6.1%)increases.But the contents decreased of 5.14%and types increased of alcohols in kiwifruit NFC juice after heat treatment,the types and contents of ketones and aldehydes increased,the types of esters decreased,and the content of esters increased of(8.14%,26.39%)after heat treatment.Compared with heat-treated kiwifruit NFC juice,ultra high pressure treated NFC juice has more fruit flavor and green color.While the heat-treated kiwifruit NFC juice has more alcohol flavor than ultra high pressure treatment NFC juice.As the storage time is extended,the aldehyde aroma of fruit juice decreased,the ester aroma increased,and the alcohol flavor increased.Studies have shown that the quality of heat-sensitive kiwifruit NFC juice with ultra-high pressure pasteurisation is better than that of heat treatment,and its overall quality could meets commercial requirements after storage for 3 weeks.