Selection of Factors for Evaluating Fruit Quality of Mid-early Ripening Apple Cultivars

In order to provide a theoretical basis for the selection of indicators for evaluating the quality of apple fruits, 22 quality parameters of 52 mid-early ripening apple cultivars were determined and analyzed by principal component analysis and hierarchical cluster analysis. Results revealed either relative independence or close correspondence among the characteristic indicators of fruit quality. The cumulative variance contribution ratio of the first seven principal components of PCA was up to 72.8%. The 52 apple cultivars were classified as 8 major groups by HCA on the basis of the measured parameters. Eight factors were suitable for a comprehensive system for the evaluation of apple quality, including the content of total soluble solids, sugar/acid ratio, browning degree, the content of magnesium, fruit firmness, fruit shape index, single fruit weight and pulp cell size.