16个苹果品种非浓缩还原汁的理化特征分析

【目的】通过研究16种苹果非浓缩还原汁（not from concentrate，NFC）果汁的8项理化指标，利用相关性分析明确指标间的关系，以简化NFC果汁品质的评价指标。此外，利用多元数据处理对不同品种苹果NFC果汁进行归类，以找到NFC果汁生产中制汁和智能复配的替代品种，为NFC果汁产业发展提供理论参考。【方法】以16个苹果品种为试材，经榨汁、灭酶、巴杀、热灌装等单元操作制备NFC果汁。通过测定16种果汁的可溶性固形物含量、pH、可滴定酸含量、固酸比、表观黏度、浊度、总酚含量及色泽品质（L^*、a^*、b^*、C^*、h°）指标，采用单因素方差分析与相关性分析对测定结果进行显著性和相关性分析。此外，利用主成分分析（PCA）、线性判别分析（LDA）、聚类分析（CA）多元数据处理方法，对16种果汁的理化指标数据矩阵进行分析，获得16个苹果品种的综合品质分类。【结果】16种苹果汁的各项理化指标均存在显著差异，其中，‘新世界’的可溶性固形物含量和浊度最高，分别为15.7 °Brix和3 720 NTU；‘澳洲青苹’的pH最低，为2.74；‘红玉’的可滴定酸含量最高，为9.6 g·L^-1（苹果酸当量）；‘秦艳’的固酸比最高，为39.24；‘元帅’‘恩派’‘桔苹’都表现出最高的表观黏度，均为3.75 mPa·s；‘富士’的总酚含量最高，为775.94 mg·L^-1（没食子酸当量）。果汁pH与固酸比（R²=0.844）、浊度与L^*值（R²=0.967）均呈极显著正相关关系（P<0.01），pH与可滴定酸含量（R²=-0.896）、固酸比与可滴定酸含量（R²=-0.918）均呈极显著负相关关系（P<0.01）。PCA、LDA和CA的分类结果完全一致，16个品种的NFC苹果汁可分为3大类，同一大类中各品种之间不同理化指标差异较小，品质、色泽十分接近，可作为NFC果汁生产和智能复配的可替代品种。【结论】可溶性固形物含量、可滴定酸含量、色值、表观黏度、总酚含量5项理化指标，可全面反映NFC果汁的品质。在果汁品质分类中，‘玉华早富’和‘乔纳金’归为一类，‘新世界’和‘秦冠’归为一类，‘新红星’‘富士’‘桔苹’‘自由’‘秦艳’‘澳洲青苹’、‘秋香’‘粉红女士’‘元帅’‘恩派’‘凉香’‘红玉’归为一类，同一类别中NFC果汁品质接近，可作为制汁和智能复配的替代品种。

Analyses of Physicochemical Properties of NFC Apple Juices from Sixteen Cultivars

【Objective】The eight physicochemical properties of the not from concentrate (NFC) apple juices from sixteen cultivars were investigated in this study. Correlation analysis of all measured variables was applied for simplifying the evaluating indicators of NFC apple juices. Moreover, multivariate data analyses were applied to categorize apple juices, in hope of finding out the alternative cultivars in NFC juice production and intelligent formulation, and thus providing theoretical basis for juice industry.【Method】NFC juices from sixteen cultivars were prepared through squeezing, inactivating enzymes, pasteurization and hot filling. Eight physicochemical properties of sixteen juices, including the total soluble solids (TSS) content, pH value, titratable acidity (TA), TSS/TA, apparent viscosity, turbidity, total phenol content (TPC) and color quality (L^*, a, b, C, ^*h°) were determined, and their differences and correlations of the properties were evaluated using variance analysis and correlation analysis methods, respectively. Additionally, principal component analysis (PCA), liner discriminant analysis (LDA) and cluster analysis (CA) were applied to analyze the data matrix of physicochemical properties to classify sixteen juices.【Result】 The results showed that physicochemical properties of sixteen juices were significantly different. The cultivar ‘Xinshijie’ had the highest TSS content (15.7 °Brix) and turbidity (3 720 NTU), while ‘Granny Smith’ possessed the lowest pH (2.74), ‘Jonathan’ possessed the highest TA value (9.6 g·L^-1, malic acid equivalent), and ‘Qinyan’ had the highest TSS/TA (39.24). Besides, three cultivars ‘Delicious’, ‘Empire’ and ‘Cox’s orange pippin’ showed the highest apparent viscosity (3.75 mPa·s), and ‘Fuji’ possessed the highest TPC (775.94 mg·L^-1, gallic acid equivalent). pH value and TSS/TA were extremely significantly positive correlation (R²=0.844), and turbidity and L^* value also showed extremely positive correlation (R²=0.967, P<0.01). However, pH and TA (R²=-0.896), as well as TSS/TA and TA (R²=-0.918) showed extremely negative correlation (P<0.01). The results from PCA, LDA and CA provided the totally same classification, and the sixteen cultivars were classified into three categories.【Conclusion】The original eight physicochemical properties could be simplified to five indicators, they are TSS, TA, color quality (L^*, a^*, b^*, C^*, h°), apparent viscosity and TPC. These five indicators can be used to reflect overall the quality of NFC apple juices. Based on the classification of juice quality, the cultivar ‘Yuhuazaofu’ and ‘Jonagold’ formed the first group, ‘Xinshijie’ and ‘Qinguan’ constituted the second group, and ‘Starkrimson’, ‘Fuji’, ‘Cox’s orange pippin’, ‘Ziyou’, ‘Qinyan’, ‘Granny Smith’, ‘Qiuxiang’, ‘Pink lady’, ‘Delicious’, ‘Empire’, ‘Liangxiang’, ‘Jonathan’ formed the third group. The cultivars in the same group can be the alternatives in NFC juice production and intelligent formulation.