COMPOSITION OF THE FRUIT OF HIGHBUSH BLUE BERRY (VACCINIUM-CORYMBOSUML) GROWN IN THE EAST OF FRANCE (VOSGES)

The fruit of highbush blueberry (Vaccinium corymbosum L.) has a pleasa nt acid flavour; the pH of its juice (3.05 to 3.25), in the 3 varietie s analysed, is very acidic. Citric acid is the major organic acid, whi le isocitric acid is not detected. Small concentrations of malic acid (0.2-0.3 g. kg-1 of mature fruit) and ascorbic acid (6 to 8 mg. kg-1) are observed. The contents in reducing sugars are found to vary betwee n 68 and 77 g. kg-1 of fruits; sucrose content is low (1.5 to 10.2 g. kg-1). The glucose/fructose ratio is approximately 1, suggesting the e xistence of an invertase activity. The protein content is low (5-7 g. kg-1 of fruit). The contents of total pectin are similar in all sample s (about 2.2 g. kg-1 of fruit) while the levels of soluble or extracta ble pectic substances are more variable. Pectins from blueberry fruit were characterized by a high degree of methyl esterification. This pro perty could be exploited in processing the fruit into marmelades or je llies. The mineral analyses showed that the soil could play an importa nt role in the mineral composition of blueberry fruits. As in Vacciniu m myrtillus L., the major change was observed for calcium and potassiu m contents.