Effects Of Different Aplle Cultivars And Processing Key Parameters On The Quality Of Not From Concentrate Apple Juices

Apple(Maluspumila Mill.)is popular all over the world as one of the most widely consumed fruits containing plentiful nutritional phytochemicals for human beings.Being the dominant position in apple production globally,China possesses both the largest apple-growing area and the largest export of fresh apple fruit.Among fruit juices,apple juice is one of the most popular juices in the world because of its,good taste,processing adaptability and nutritional value.Although non-thermal treatment has been developed during past decade,thermal treatment is still an important and most widely used sterilizing method in food processing industry currently.Regarding the thermal treatment,many production technologies have been designed for apple juice processing.However,some of these technologies may provide similar characteristics to the final juices.Thus,it will be a tendency to simplify and integrate the current,technologies based on the similar product quality.Additionally,not from concentrate(NFC)juice has an increasing market value in these years because it is a convenient food product with a natural flesh appearance,texture and flavor.Being different from apple juice from concentrate,NFC apple juice requires good quality of raw material and final product.Thus,juice producers in different area always choose certain cultivars to produce apple juice,ensuring juices exhibit relatively coincident quality for each batch.However,the apple yield and quality are directly affected by many factors,including bacterial diseases,fungal diseases,insect pests and even natural disasters.The exploration of alternative apple cultivars using in juice production is expected to solve this problem.In this study,NFC apple juices were prepared in pilot and lab scale,respectively.9 industrial production technologies were integrated and simplified into 3 groups of technologies.The effect of certain unit operation on the quality of NFC apple juice was demonstrated.The alternative apple cultivars using in juice production were determined according to the physicochemical and/or polyphenolic properties of NFC apple juices.The detailed results were shown as follows:1.Apple juices produced from different nine industrial production technologies were obtained in pilot scale,for simplifying and integrating the production technologies according to the quality comparison of juices.Juice quality characterized by total phenolic content(TPC),total flavonoids content(TFC),total soluble solid(TSS),stability,turbidity,titratable acidity(TA)and pH were investigated.The TPC of traditional pulping combined with belt-style pressing(TP+BSP)based juices were higher than that of cold pulping combined with horizontal spiral centrifuge separation(CP+HSCS)based juices,while the CP+HSCS juices showed higher turbidity than the TP+BSP juices.Principle component analysis(PCA),liner discriminant analysis(LDA)and hierarchical cluster analysis(HCA)were applied for analyzing juice quality.Nine production technologies were well-separated into three categories,and that pulping,juicing and sterilizing methods were the main factors affecting the overall juice quality.This study provided a method to simplify and integrate the current industrial production technologies of juices.2.The effects of unit operations on the quality of NFC apple juice were investigated in this study.Juice samples after the main processing steps(juicing,killing enzyme,homogenization and thermization)were collected and characterized by TSS,TA,pH,turbidity,non-enzymatic browning index(NEBI),color quality and aroma.PCA and HCA were applied for analyzing juice aroma.The results showed that homogenization only affected(increased)the juice turbidity,and only the TSS content was not affected by the unit operations.The TA,pH,and aroma component of the NFC apple juice were significantly decreased,while the turbidity,NEBI,color values were significantly increased by killing enzyme.Thermization had less effect on these properties than killing enzyme.Therefore,it is the thermal treatments that mainly affected the juice quality during NFC apple juice production.3.The physicochemical properties,including TSS,pH value,TA,turbidity,TSS/TA and color values of NFC apple juices of sixteen cultivars in the same producing region in China were determined.The results showed that the physicochemical properties affecting juice quality varied with the apple cultivars.Besides,phenolic composition and content in the apple juices were analyzed using ultra performance liquid chromatography(UPLC).There were 13-15 kinds of polyphenols found in the NCF juices,in which procyanidin B2,chlorogenic acid and epicatechin were the main phenolic components.Both the physicochemical and phenolic properties were further analyzed using PCA and HCA.The juices of sixteen cultivars were classified into three groups showing similar quality score based on the physiochemical properties,and two main groups based on the polyphenolic constitutes.The cultivars classified into the same group may be used as the alternatives in NFC juice production.In conclusion,this study developed the relative theoretical research concerning the NFC apple juice based on the existing research of juice processing.It established the theoretical foundation for industrial application,industrial chain extension and intelligent combination of NFC apple juice in China.