Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 2011
Publication Date: December 16, 2011
Citation: Wang, S.Y., Camp, M.J., Ehlenfeldt, M.K. 2011. Antioxidant capacity and alpha-glucosidase inhibitory activity in peel and flesh of blueberry (Vaccinium sp.) Cultivars. Food Chemistry. 132:1759-1768. Interpretive Summary: Consumption of fruits and vegetables rich in antioxidant compounds is associated with improved human health. One of our goals was to develop new blueberry cultivars with enhanced antioxidant and alpha-glucosidase inhibitory activities. Alpha-glucosidase inhibitors have the potential to decrease glucose absorption and thus help regulate blood glucose levels. In order to select the best candidates for use as parents in the breeding program, we first characterized the variation in antioxidant activities and alpha-glucosidase inhibitory activities among 33 diverse blueberry cultivars. We found that there were great variations in these parameters among cultivars and also between tissues (peel and flesh). Peel tissue possessed higher antioxidant activity and alpha-glucosidase inhibitory activity than flesh tissue. Several rabbiteye type blueberries had the highest antioxidant activity and alpha-glucosidase inhibitory activity. Characterization of these blueberry cultivars will enable their use in future blueberry breeding to develop new blueberry cultivars with both high alpha-glucosidase inhibitory activity and high antioxidant activity. This information is useful to consumers, blueberry breeders and growers, and the blueberry industry.
Technical Abstract: This study was designed to evaluate cultivar variations in phenolic content, anthocyanin content, and antioxidant activity of peel and pulp to determine their potential inhibitory effects on alpha–glucosidase in 33 blueberry (Vaccinium species) cultivars including 29 rabbiteye (Vaccinium ashei Reade) blueberries, two V. ashei hybrid derivatives, and two northern highbush. The relation of phenolic, anthocyanin, and antioxidant activity to a–glucosidase inhibition in blueberries also was investigated. It was found that peel tissue possessed higher levels of total anthocyanins, total phenolics, antioxidant capacity, and a-glucosidase inhibitory activity than flesh tissue in all blueberries tested except the pink-fruited hybrid type ‘Pink Lemonade’. The percentage contributions of peel to whole berry on scavenging capacity against peroxyl free radicals (ROO'), hydroxyl radicals ('OH), hydrogen peroxide (H2O2), and singlet oxygen (1O2) radicals were higher than those of flesh, even though the fruit contained much higher amounts of flesh than peel in terms of fresh weight and dry weight. Cultivars with high levels of phenolic compounds, antioxidant capacities, and a-glucosidase inhibitory activities could be selected for use in blueberry breeding programs to develop new lines with improved health benefits.