Phenolics and betacyanins in red beetroot (Beta vulgaris) root: distribution and effect of cold storage on the content of total phenolics and three individual compounds

The distribution of total phenolics and main betacyanins in red beetroot (Beta vulgaris) root was determined. Also, the subsequent effects of cold storage on the content of total phenolics, main betacyanins (betanin and isobetanin), and the main known ferulic acid ester (beta-D-fructofuranosyl-alpha-D-(6-O-(E)-feruloylglucopyranoside) were determined in the peel, which is the root part containing the largest amount of total phenolics. The content of total phenolics in the red beetroot water extracts was determined according to a modification of the Folin-Ciocalteu method and expressed as gallic acid equivalents (GAE). The compounds of interest were identified by HPLC-ESI-MS and NMR techniques, and the contents of compounds were determined by HLPC analyses. The total phenolic contents in various root parts were found to decrease in the order peel, crown, flesh. Significant differences in the contents of total phenolics and individual compounds were found when the effect of cold storage (5 degrees C, 0-196 days) on the constituents of the peel from intact roots was examined. In addition to the betacyanins of red beetroot peel found in our earlier study, tentative identifications of betanidin and feruloylamaranthin were made.