Antioxidant Capacity, Anthocyanin Content Profile in ‘Bluecrop’ Blueberry Fruit

Mature ‘Bluecrop’ berries, with no visible damage on the fruit surface, were picked by hand and placed in a common cold storage (as control) and under CA conditions consisting of 8 different CO₂:O₂ ratios (12:1.5, 12:3, 12:6, 12:12 and 18:1.5, 18:3, 18:6, 18:12) at 0°C. HPLC was used to separate and determine individual anthocyanin compounds in blueberry fruit. ‘Bluecrop’ blueberries contained 14 anthocyanins: glycosides of delphinidin, cyanidin, peonidin, petunidin and malvidin all with sugar bound at the 3-position. Generally, the content of anthocyanin compounds in fruit was the highest after 2 or 4-week storage. Total anthocyanin content was significantly higher in berries stored under CA condition, especially under low oxygen concentration, as compared with those placed in common cold storage, and CO₂ concentration does not have any effect. Antioxidant activity strongly correlated with total anthocyanin content, delphinidin-3-glucoside, delphinidin-3-galactoside, delphinidin-3-arabinoside, petunidin-3-glucoside, petunidin-3-galactoside and with firmness, but slightly correlated with soluble solids and titratable acidity.