Berry Health Symposium Abstract

Anthocyanins, Polyphenolics and Antioxidant Properties of Pacific Northwest Fruits

Ronald E. Wrolstad, Food Science & Technology, Oregon State University

Oregon's Willamette Valley produces a diverse range of high-quality horticultural crops. Being a long-distance from major population centers, the industry has focused on processed fruits; OSU's Food Science & Technology Department has worked cooperatively with the Horticulture Department and USDA scientists since the 1920's in evaluating the suitability of new cultivars for processing. Much of our laboratory's efforts have been directed to the interrelationships between fruit chemical composition and the quality of fresh and processed fruits. Because of the importance of color quality, anthocyanin pigments and their degradation during processing and storage has been a major topic. Analyses of anthocyanins and polyphenolics have also been useful in determining fruit juice authenticity. The major interest in recent years, however, has been the antioxidant properties and possible health benefits of fruits. We have determined the total anthocyanins, total phenolics and antioxidant capacity (ORAC & FRAP) of 107 genotypes of Vaccinium, Rubus, and Ribes.  There was wide diversity of phytochemical levels and antioxidant capacities with and across the three genera. For highbush blueberries (V. corymbosum L., fruit size was inversely correlated (r = 0.84) total anthocyanins. Considerable destruction of anthocyanins and polyphenolics occurs when blueberries are processed into juice and juice concentrate. Pigment recovery is low, with considerable pigment remaining in the press-cake residue. This material is actually a rich source of anthocyanins and polyphenolics that can be utilized for natural colorants and nutraceuticals. Seeds are another processing waste that is a rich source for phytochemicals. Blackberry seeds and strawberry achenes are rich in ellagitannins, ellagic acid and procyanidins. We recently investigated the effect of maturity and sampling on blackberry anthocyanins, polyphenolics and antioxidant properties.  In contrast to total anthocyanins, total phenolics did not show a marked change with maturity with values slightly decreasing from underripe to ripe. Antioxidant activities, while increasing with ripening, also did not show the marked change that total anthocyanins exhibited. The impact of variation due to plots, subsampling, sample preparation, and measurement on Marionberry composition was examined in detail. Plot-to-plot and sample differences were the major contributors to variation, with sample preparation being an important contributor for some parameters. Measurement variation was a relatively small component of the total variation. In addition to blueberries, red and black raspberries, blackberries and strawberries we have analyzed native huckleberries (V. membranaceum, V. ovalifolium, V. deliciosum, V. ovatum), chokeberries (Aronia melanocarpa), and blue honeysuckle (Lonicera caerulea L.), that are rich in anthocyanin pigment and polyphenolics and potential new crops for the Pacific Northwest. While anthocyanin content has a high correlation with antioxidant properties, in general we find higher correlations with total phenolics.

Key Words: Anthocyanin pigments, polyphenolics, antioxidant properties, processing effects, maturity, sampling, blueberries, blackberries, huckleberries, blue honeysuckle, chokeberries.

Key References

Aaby, K., G. Skrede and R.E. Wrolstad. 2005. Phenolic composition and antioxidant activities in flesh and achenes of strawberries (Fragaria ananassa). J. Agric. Food Chem. In press.

Chaovanalikit, A., M.M. Thompson and R.E. Wrolstad. 2004. Characterization and quantification of anthocyanins and polyphenolics in Blue Honeysuckle (Lonicera caerulea L.)  J. Agric. Food Chem.52:848-852.

Lee, J.,  R. W.Durst and R. E. Wrolstad. 2002. Impact of juice processing on blueberry anthocyanins and polyphenolics: Comparison of two pre-treatments. J. Food Sci. 67: 1660-1667.

Lee, J., C.E. Finn, and R.E. Wrolstad. 2004. Anthocyanin pigment and total phenolic content of three Vaccinium species native to the Pacific Northwest of North America. HortScience 39:959-964.

Lee, J. and R.E. Wrolstad. 2004. Extraction of anthocyanins and polyphenolics from blueberry processing waste.  J. Food Sci. 69: C564-573.

Moyer, R. A., K. E. Hummer, C. E. Finn, B. Frei, and R. E. Wrolstad. 2002. Anthocyanins, phenolics and antioxidant capacity in diverse small fruits: Vaccinium, rubus and Ribes. J. Agric. Food Chem.50:519-525.

Skrede, G., R. E. Wrolstad and R. W. Durst. 2000. Changes in anthocyanins and polyphenolics during juice processing of highbush blueberries (Vaccinium corymbosum L.) J. Food Sci. 65: 357-364.

Siriwoharn, T. and R.E. Wrolstad. 2004. Polyphenolic composition of Marion and Evergreen blackberries. J. Food Sci. 69:FCT233-240.

Siriwoharn, T., R.E. Wrolstad, C.E. Finn & C.B. Pereira. 2004. Influence of cultivar, maturity and sampling on blackberry (Rubus L. hybrids) anthocyanins, polyphenolics, and antioxidant properties. J. Agr. Food Chem.52: 8021-8030.

Sirowoharn, T., R.E. Wrolstad and R.W. Durst. 2005. Identification of ellagic acid in blackberry juice sediment. J. Food Sci. 70. In press.