COMPOSITIONAL CHANGES IN BLUEBERRY AND CRANBERRY FRUIT DURING RIPENING

Abstract

Compositional changes that occur during fruit ripening affect both the organ-oleptic and nutritional quality of small fruit. Understanding these developmental changes may aid optimization of fruit quality. Blueberry (Vaccinium corymbosum L.) and cranberry (Vaccinium macrocarpon Aiton) fruit were harvested at 3 maturities (white, turning and fully colored) from commercial fields during 2 seasons and fruit composition was analyzed for sugars, acids, total phenolics, total anthocyanins, ORAC antioxidant capacity, and fruit firmness. In blueberry fruit the primary sugars were glucose and fructose, which increased from about 2 to 6% as fruit ripened from white to blue. Citric acid comprised 60 to 80% of the organic acids in blueberries and declined by 60% as fruit ripened from white to blue. Additional acids present consisted of quinic, malic, and small amounts of succinic and tartaric acids. Total blueberry phenolics in turning fruit were 60% less than in white fruit and 12% less than in blue fruit. Anthocyanins increased as color developed. Antioxidant capacity declined as fruit ripened from white to turning. Fruit firmness decreased about 80% as fruit ripened from white to blue. The composition of cranberry fruit did not change as much as blueberries during ripening. Sugar concentration increased from about 2.2 to 3.2% as fruit ripened from white to red with glucose comprising 82 to 74% of the total sugars, respectively. During the same time, acid content decreased by only 22%. Citric acid comprised over 50% of the acids in white cranberry fruit, but declined to about 30% in ripe fruit, while quinic and malic acids increased to 30 and 40% respectively. Similar to blueberries, total anthocyanins increased as color developed, and total phenolics and antioxidant capacity remained relatively constant. In contrast to blueberries, red cranberry fruit were firmer than white or turning fruit.