Quality Changes In Cloudy Apple-kiwifruit Mixed Juice:Innovative Clean Label Concept

Nowadays,consumers are increasingly demanding natural and health-oriented cloudy fruit juice as cloud imparts characteristic flavor,color,nutrients,and mouthfeel.For processed cloudy juice,browning,cloud loss,and flavor loss are major quality defects occurring during processing and subsequent shelf-life.The research objective is to evaluate to what extend the integration of novel physical treatment technologies can be combined with kiwifruit puree to create a clean label cloudy apple juice.The objective is realized through the implementation of three work packages.(1)As the clean label ingredient,the quality of kiwifruit puree is sensitive to manurity and cultivars.In this package,two different kiwifruit cultivars(gold and green kiwifruit)during late ripening stages were investigated.Most of quality attributes of two kiwifruit are similar.During late ripening,hardness decreased significantly and soluble solids content increased.The color of kiwifruit puree turned dark and more yellow.Sucrose decreased significantly with glucose and fructose increasing accordingly.The formation of esters,sand a decrease of aldehydeswas observed.However,the changes in ascorbic acid concentration of two kiwifruit showed different trends,where the ascorbic acid content in green kiwifruit decreased and gold kiwifruit increased during late ripening.(2)In this work package,high pressure pasteurization is compared with conventional thermal processing on maintaining fresh fruit quality characteristics of cloudy apple juices and kiwifruit puree.High pressure processing provided a better retention of color and vitamin C than thermal processing,which can also avoid the formation of typical temperature induced volatile compounds.Besides,gold kiwifruit puree displayed similar color and flavor characteristics as cloudy apple juice(Jonagold).Gold kiwifruit puree can be selected as clean label ingredient in the further storage study.(3)The capacity of a combination of kiwifruit puree and structure enabling technologies,i.e.high pressure homogenization,to control quality loss of high pressure pasteurized cloudy juice is evaluated,Cloudy apple juice was firstly mixed with 25%gold kiwifruit puree and subsequently homogenized at 20 MPa.After pasteurization by high pressure processing at 600 MPa for 3 min,the juices were stored at 4℃ for 6 weeks.This work clearly demonstrated that enzymatic browning and cloud loss in cloudy apple juice can be minimized to a great extent by mixing with kiwifruit puree,which due to the high ascorbic acid content nd high viscosity of kiwifruit puree.Similar trends of volatiles in both juices were detected,esters being degraded.Based on visual and sensory evaluations,positive preferences for quality was noted for juices with kiwifruit puree added.Therefore,a combination of clean label ingredient with physical processing technologies to stabilize the quality attributes of cloudy fruit juice offers new opportunities.Future research can be carried out to further investigate the application of clean label options in a wide range of products.