Abstract:Sugars and acids are important components that contribute to the flavor of fruit. To identify the sugar-acid flavor indexes and analyze the compositional difference in sugar-acid flavor among jujube varieties, as well as establish the evaluation system for sugar-acid flavor are of great significance. By taking use of 210 jujube varieties, here we measured and analyzed the contents of soluble solids, titrable acids, and sugar components in fruit at the crisp ripening stage. The results were as follows: (1) The coefficient of variation ranged from 9.81% - 34.70% for the 10 indexes, including soluble solids, sweetness value, and total sugar that show smaller coefficient. The range of sucrose content varied the most, with the maximum being 84.54 times that of the minimum. Except soluble solid and sweet-acid ratio,eight indexes, including fructose, glucose, sucrose, total sugar, titrable acid, sweetness value, solid-acid ratio and sugar-acid ratio, were observed with the normal distribution. (2) The fructose, glucose and sucrose significantly positively correlated with total sugar content. A significant positive correlation between fructose and glucose content, as well as the significant positive correlation among total sugar, soluble solid and sweet value were observed. Titrable acid significantly negatively correlated with solid-acid ratio, sugar-acid ratio and sweet-acid ratio. The significant correlations among the solid-acid ratio, sugar-acid ratio and sweet-acid ratio were observed. (3) Factor analysis extracted three main factors with a cumulative contribution rate of 91.781%. Combined with the cluster analysis of various indexes, five indexes, including fructose, sucrose, soluble solid, titrable acid and solid-acid ratio, were selected to evaluate the sugar-acid flavor of jujube fruit. (4) Based on the five evaluation indexes, cluster analysis suggested five groups in 210 jujube varieties. These groups were defined as low sucrose type, high acid type, fructose dominant type, intermediate type and sucrose dominant type, where the sucrose dominant type contained the largest number of varieties. Collectively, the evaluation of sugar-acid flavor in jujube fruit can be performed using the five indexes, and the application of jujube varieties by considering the sugar and acid indexes could be desirable in production.