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Journal of Biomedicine and Biotechnology
Volume 2004 (2004), Issue 5, Pages 248-252
http://dx.doi.org/10.1155/S1110724304406123
Research article

The Change of Total Anthocyanins in Blueberries and Their Antioxidant Effect After Drying and Freezing

Food Science and Technology, School of Chemical Engineering and Industrial Chemistry, The University of New South Wales, Sydney 2052, NSW, Australia

Received 26 April 2004; Revised 11 June 2004; Accepted 29 June 2004

Copyright © 2004 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study examined the effects of freezing, storage, and cabinet drying on the anthocyanin content and antioxidant activity of blueberries (Vaccinium corymbosum L). Fresh samples were stored for two weeks at 5C while frozen samples were kept for up to three months at 20C. There were two drying treatments, one including osmotic pretreatment followed by cabinet drying and the other involving only cabinet drying. Total anthocyanins found in fresh blueberries were 7.2±0.5 mg/g dry matter, expressed as cyanidin 3-rutinoside equivalents. In comparison with fresh samples, total anthocyanins in untreated and pretreated dried blueberries were significantly reduced to 4.3±0.1 mg/g solid content, 41% loss, and 3.7±0.2 mg/g solid content, 49% loss, respectively. Osmotic treatment followed by a thermal treatment had a greater effect on anthocyanin loss than the thermal treatment alone. In contrast, the frozen samples did not show any significant decrease in anthocyanin level during three months of storage. Measurement of the antioxidant activity of anthocyanin extracts from blueberries showed there was no significant difference between fresh, dried, and frozen blueberries.