Fruit Biochemical Content of Wild Aronia Germplasm

Dark-colored fruits of the genus Aronia (chokeberry) are high in antioxidants and have been recognized for their potential as a new nutraceutical fruit crop. Aronia species which produce dark-colored fruits include mitschurinii, prunifolia, and melanocarpa, in both diploid and tetraploid forms. A replicated planting of wild Aronia accessions was used to determine how the fruit from wild germplasm compared biochemically to fruit from cultivated forms of chokeberry. Over two years, we quantified percent water content, total phenolics by Folin-Ciocalteu assay, total anthocyanins by HPLC and spectrophotometer, individual anthocyanins by HPLC and oxygen radical adsorption capacity (ORAC) by assay. Aronia genotypes analyzed included seven mitschurinii, 17 diploid melanocarpa, 13 tetraploid melanocarpa, and 11 prunifolia for a total of 48 accessions. There were considerable differences in total anthocyanins, total phenolics and ORAC values between accessions of Aronia. Accessions with the highest total phenolics content and ORAC values were twice those of the lowest values for accessions. For total anthocyanin content, the highest accessions were nine times higher than the lowest accessions. In both years, fruits of mitschurinii accessions had the highest average water content, while fruits of prunifolia accessions had the lowest water content. Diploid melanocarpa fruits had the highest levels of total anthocyanins, while prunifolia fruits had the lowest concentrations. Prunifolia fruits contained the greatest concentrations of total phenolics, while either mitschurinii or diploid melanocarpa had the lowest concentrations, depending on the year. The ORAC levels were highest for diploid melanocarpa fruits in both years, while mitschurinii fruits had the lowest ORAC values. In comparing Aronia fruit from 2010 to 2011, values for water content, total anthocyanins, total phenolics and ORAC decreased for all taxonomic groups. Over all accessions, water content decreased 4%, anthocyanin content decreased by 29%, total phenolics content decreased by 17% and ORAC decreased by 13%. Maximum differences observed between years for individual accessions were 12% for water content, 66% for anthocyanin content, 44% for total phenolics content and 45% for ORAC. Significant differences in fruit biochemical composition among wild Aronia accessions make this germplasm useful in a breeding program to develop new nutraceutical cultivars. Significant year to year variation in fruit biochemical composition can be expected and significant variation between genotypes of the same taxonomic group can exist.