Evaluation of sugar and organic acid composition and their levels in highbush blueberries from two regions of China

Sweet and sour are the most important taste of blueberries, and they are produced by sugar and acid, respectively. Their contributions to the taste depend not only on the levels of sugar and acid, but also on the types and relative proportions of sugar and acid. Therefore, it is very important to evaluate the composition and levels of sugar and acid in blueberries. Regional differences and variety diversity also affect the sugar and acid characteristics of fruits. Therefore, this study selected two main producing regions in northern China(Weihai and Yingkou) to examine the sugar and acid characteristics of 11 common blueberry cultivars. The indexes measured included soluble sugars, organic acids, soluble solid content and titratable acidity. The results showed that glucose and fructose were the major sugars, and citric acid and quinic acid were the major organic acids. Correlation analysis showed that glucose, fructose, and sucrose were positively correlated with total sugar content; the citric acid content was positively correlated with the titratable acidity and total organic acids. Titratable acidity, glucose, fructose, sucrose, total sugar content, citric acid, shikimic acid and total acid content of the blueberries varied significantly between regions(P0.05). In general, compared with Weihai blueberries, Yingkou blueberries had higher sugar content and lower acid content. The results of this study may provide useful references for the evaluation of sweet and sour flavors and cultivar selection of blueberries.