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Title: Processing and Storage Effects on Monomeric Anthocyanins, Percent Polymeric Color, and Antioxidant Capacity of Processed Blackberry Products

Author
item HAGER, TIFFANY
item HOWARD, LUKE
item Prior, Ronald

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2007
Publication Date: 2/1/2008
Citation: Hager, T., Howard, L., Prior, R.L. 2008. Processing and storage effects on monomeric anthocyanins, percent polymeric color, and antioxidant capacity of processed blackberry products. Journal of Agricultural and Food Chemistry. 56(3):689-695.

Interpretive Summary: Blackberries are a rich source of polyphenolics, particularly anthocyanins, that may contribute to the reduced risk of chronic disease; however, as with most berries, the fresh fruit are only seasonally available. With most of the blackberries consumed as frozen or in thermally processed forms after long-term storage, the purpose of this study was to evaluate the effects of processing and 6 months of storage on the anthocyanins and antioxidant capacity of blackberries that were individually quick-frozen, canned-in-syrup, canned-in-water, pureed, and juiced (clarified and nonclarified). Anthocyanins, which are responsible for the dark color of blackberries, were lost during storage but appeared to aggregate into larger molecules. For most products, processing also resulted in losses in antioxidant capacity. Storage at 25 °C of all processed products resulted in dramatic losses (up to 75%) in simple anthocyanins, which coincided with marked increases in the amount of color accounted for in the form of larger molecules in these products over 6 months of storage. There were no changes in antioxidant capacity for processed products throughout long-term storage. No significant changes in antioxidant capacity or anthocyanin content were observed in individually quick-frozen fruit during long-term storage at -20 °C.

Technical Abstract: Blackberries are a rich source of polyphenolics, particularly anthocyanins, that may contribute to the reduced risk of chronic disease; however, as with most berries, the fresh fruit are only seasonally available. With most of the blackberries consumed as frozen or in thermally processed forms after long-term storage, the purpose of this study was to evaluate the effects of processing and 6 months of storage on the anthocyanins and antioxidant capacity of blackberries that were individually quick-frozen (IQF), canned-in-syrup, canned-in-water, pureed, and juiced (clarified and nonclarified). Monomeric anthocyanins, percent polymeric color, and antioxidant capacity by oxygen radical absorbance capacity (ORACFL) and photochemiluminescence (PCL) were determined postprocessing (1 day) and after 1, 3, and 6 months of storage. Processing resulted in increases in polymeric color values (up to 7%) and losses in monomeric anthocyanins (up to 65%). For most products, processing also resulted in losses in antioxidant capacity (by ORACFL and PCL). Storage at 25 °C of all processed products resulted in dramatic losses in monomeric anthocyanins, with as much as 75% losses of anthocyanins throughout storage, which coincided with marked increases of percent polymeric color values of these products over 6 months of storage. There were no changes in ORACFL or PCL for processed products throughout long-term storage. No significant changes in antioxidant capacity or anthocyanin content were observed in IQF fruit during long-term storage at -20 °C.