Comparative Analysis of Sugar and Organic Acid Contents of Different Apple Cultivars in Dryland of Loess Plateau

In order to clarify the characteristics of soluble sugar and organic acid contents among different varieties of apple fruits in the dry area of loess plateau, the contents of sugar and acid in the fruits of 30 main varieties were analyzed. The soluble sugar and organic acid contents in 30 varieties of ripe fruits were tested by high-performance liquid chromatography (HPLC), and the data were analyzed for one-way ANOVA and correlation. The results showed that the fructose contents was the highest in different varieties of apple fruit sugar group with an average value of 52.964 mg/g, accounting for 48.52% of the total sugar contents, and the two were extremely significantly related (r=0.787), and the highest fructose contents was ‘gala’ (69.736 mg/g), the sucrose contents in most apple varieties were higher than glucose, and only 3 varieties showed that glucose contents were higher than sucrose contents, respectively ‘Golden Delicious’, ‘August Fuji’ and ‘Gold Spur’. The main organic acid in different apple varieties was malic acid, with an average value of 3.857 mg/g, accounting for 58.74% of the total acid contents, and the two were extremely significantly related (r=0.845), the contents of quinine acid was second, other types of organic acids contents were low, the variety with the highest malic acid contents was ‘Hanfu’ (8.109 mg/g). There were 3 varieties with sweetness value/total acid contents greater than 30, respectively ‘World No1’, ‘Golden Delicious’ and ‘Gala’, and 13 varieties between 20 and 30, and 14 varieties with less than 20. The sweetness value and total acid contents of apple fruit, as well as their ratio affected the flavor of fruit together.