UNIQUE ORGANIC-ACID PROFILE OF RABBITEYE VS HIGHBUSH BLUEBERRIES

The fruit of six highbush (Vaccinium corymbosum L.) cultivars and eight rabbiteye (V. ashei Reade) cultivars and selections were evaluated by high-performance liquid chromatography for levels of the commonly found organic acids, citric, malic, succinic, and quinic. The two cultivar groups possessed distinctive patterns of relative organic acid proportions that could unambiguously separate pure rabbiteye and highbush clones in a principal component analysis. Highbush clones were characterized by high citric acid content, with percentages averaging 75% (range 38% to 90%). Succinic acid was the second most plentiful acid, averaging 17%. In contrast, rabbiteye cultivars and selections contained 10% citric acid, and no clone had >22%. Succinic acid and malic acid were found in greater quantities than in highbush, averaging 50 % and 34 %, respectively. Analysis of the fruit of seven albino-fruited highbush selections exhibited a profile similar to standard highbush cultivars, but with a citric acid average of <50%, and proportionally greater amounts of succinic and quinic acids. Given the differences in sensory quality of these four acids, it is likely that acid partitioning patterns can largely account for some of the perceived flavor differences between rabbiteye and highbush blueberries. Because several current breeding efforts involve hybridization between highbush and rabbiteye blueberries, a consideration of acid composition of breeding parents may be worthwhile.