Processing and storage effects on procyanidin composition and concentration of processed blueberry products.

Blueberries are a rich source of procyanidins that may contribute to the reduced risk of chronic disease; however, because of seasonal availability, the berries are commonly consumed in thermally processed forms after long-term storage. In this study, we evaluated the effects of processing and 6 months of storage on procyanidin composition and content of blueberries that were canned in syrup (CS), canned in water (CW), pureed, and juiced (nonclarified and clarified). Processing blueberries into various forms resulted in significant losses of total procyanidins, with only 19 and 23% being retained in nonclarified and clarified juices, 41% retained in purees, and 65 and 78% being retained in berries CS and CW. The mono- and dimers were retained to a much greater extent than larger oligomers in all products following processing. Procyanidins were further degraded during 6 months of storage, with only 8% and 11% retained in clarified and nonclarified juices, 7% retained in pureed, and 22 and 32% retained in berries CS and CW. Similar to results obtained following processing, mono- and dimers were better retained than larger oligomers. Methods are needed to prevent procyanidin losses during processing and storage.