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ARS Home » Southeast Area » Little Rock, Arkansas » Arkansas Children's Nutrition Center » Research » Publications at this Location » Publication #194233
Title: PROCESSING EFFECTS ON BLACK RASPBERRY POLYPHENOLICS AND ANTIOXIDANT CAPACITY

Author
item HAGER, A - UNIVERSITY OF ARKANSAS
item HOWARD, L - UNIVERSITY OF ARKANSAS
item Prior, Ronald

Submitted to: Food Science Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/21/2006
Publication Date: 6/23/2006
Citation: Hager, A., Howard, L., Prior, R.L. 2006. Processing effects on black raspberry polyphenolics and antioxidant capacity. Institute of Food Technology Annual Meeting, June 24-28, 2006, Orlando, Florida. Paper No. 039G-27.

Interpretive Summary: Epidemiological studies have shown that diets high in fruits and vegetables may contribute to a lower incidence of chronic diseases due to the presence of antioxidants, such as polyphenolics, with berries being one of the most significant sources. Black raspberries, compared to other berries, are particularly rich in polyphenolics, but the effects of processing on the polyphenolic content and antioxidant capacity of the berries are unknown. Juicing and canning resulted in losses compared to fresh berries. Freezing results in minor losses of polyphenolics and antioxidant capacity in black raspberries, but preservation methods involving thermal treatments cause significant losses of anthocyanins and antioxidant capacity in the fruit. Methods are needed to prevent losses of anthocyanins and antioxidant capacity in thermally processed black raspberry products.

Technical Abstract: Epidemiological studies have shown that diets high in fruits and vegetables may contribute to a lower incidence of chronic diseases due to the presence of antioxidants, such as polyphenolics, with berries being one of the most significant sources. Black raspberries, compared to other berries, are particularly rich in polyphenolics, but the effects of processing on the polyphenolic content and antioxidant capacity of the berries are unknown. The objective of this study was to evaluate the effects of processing on the polyphenolic content and antioxidant capacity of black raspberries. Fresh black raspberries (cultivar Munger) were processed as individually quick frozen (IQF), canned in water, canned in syrup (40o brix), purees (18o brix), clarified and non-clarified juices. After one month of storage processed samples were analyzed for total phenolics, total monomeric anthocyanins and polymeric color using colorimetric assays. Antioxidant capacity of the samples was determined by the Oxygen Radical Absorbance Capacity (ORAC) assay. The total phenolics, ORAC, and total anthocyanins of IQF berries decreased 8, 10, and 20%, respectively compared to fresh berries. Puree total phenolics remained unchanged, but ORAC decreased by 40% and anthocyanins decreased by 60% compared to fresh berries. Non-clarified and clarified juices experienced significant losses of total phenolics (14-21%), ORAC (44-45%), and total anthocyanins (44-51%) compared to fresh berries. Canned-in-water and canned-in-syrup samples also experienced significant losses of total phenolics (10-12%), ORAC (41-53%), and total anthocyanins compared to fresh berries. Polymeric color was observed only in thermally processed samples, with juices having the highest values. Freezing results in minor losses of polyphenolics and antioxidant capacity in black raspberries, but preservation methods involving thermal treatments cause significant losses of anthocyanins and antioxidant capacity in the fruit. Methods are needed to prevent losses of anthocyanins and antioxidant capacity in thermally processed black raspberry products.