Antioxidant Capacities and Flavonoid Constituents of Various Blueberry Cultivars (Vaccinium species)

Fruit from forty-two blueberry cultivars, including thirty-six rabbiteye (Vaccinium ashei Reade), three V. ashei hybrid derivatives and three northern highbush (V. corymbosum L.) standards were evaluated for antioxidant capacity [against peroxyl free radicals], hydroxyl radicals, hydrogen peroxide, superoxide radicals, and singlet oxygen radicals], flavonoid content, and the contribution of each identified phenolic compound to total antioxidant activity. Considerable variations were found in these parameters among cultivars. Extracts from fruit of rabbiteye had higher levels of scavenging capacities for oxygen species compared to V. ashei hybrid derivatives (‘Pearl River’, ‘Snowflake’, and ‘Pink Lemonade’) and northern highbush blueberry standards (‘Bluecrop’, ‘Duke’ and ‘Elliott’). The contribution of individual phenolics to total antioxidant capacity was generally dependent on their content in the berries and their structure. Among 42 blueberry cultivars, the rabbiteye ‘Early May’ contained the highest amount of chlorogenic acid, myricetin 3-arabinoside, quercetin derivatives and delphinidin-, cyanidin-, petunidin-, and malvidin-based anthocyanins, and also had the highest antioxidant activity. Other rabbiteye cultivars ‘Owen’, ‘Bluegem’, ‘Clara’, Climax’, and ‘Centurion’ also had high levels of flavonoids and antioxidant activities. In contrast, the pink-fruited V. ashei hybrid ‘Pink Lemonade’ had the lowest content of flavonoids and antioxidant activity. The antioxidant activity of V. ashei hybrid derivatives was mainly derived from chlorogenic acid, myrecetin, and quercetin (62.5%), whereas anthocyanins (malvidin, petunidin, delphinidin and cyanidin) were the main contributors to the antioxidant activity of rabbiteye cultivars (76.2 %) and northern highbush standards (76.8%). Blueberry cultivars with high phenolic content, antioxidant activity and radical scavenging capacity have potential to be used as parents in blueberry breeding programs to develop new blueberry cultivars with high flavonoid content and high antioxidant activity.