Cooked blueberries: anthocyanin and anthocyanidin degradation and their radical-scavenging activity

This study examined anthocyanin and anthocyanidin composition and radical-scavenging activity of three cultivars of blueberries (Vaccinium corymbosum L., cv. Bluecrop, Bluetravel, and Ozarkblue) before and after cooking. A total of 13 anthocyanins were separated and monitored in methanolic extracts of raw fruits by high-performance liquid chromatography/diode array detector (HPLC/DAD). Principal component analysis using the anthocyanin profile as variables revealed differences according to cultivar origin. Of the six common anthocyanidins, four were identified and quantified in the hydrolysates, namely, malvidin, the most abundant, followed by cyanidin, petunidin, and delphynidin. A systematic evaluation of the degradation of anthocyanins and anthocyanidins of blueberries cooked in stuffed fish was performed. The percentage of anthocyanin degradation in cooked blueberries (by progressive heating from 12 to 99 °C for 60 min) ranged between 16 and 30% for Bluecrop, 30-42% for Bluetravel, and 12-41% for Ozarkblue. However, cooked blueberries maintained or increased radical-scavenging activity when evaluated by the 1,1'-diphenyl-2-picrylhydrazyl (DPPH) method. Overall, results show that cooked blueberries can serve as a good source of bioactive phytochemicals.