Approach to the content of total extractable phenolic compounds from different food samples by comparison of chromatographic and spectrophotometric methods

A new approach to the error sources in the spectrophotometric determination of total phenols in foods has been performed. The choice of the suitable p henolic standard and the influence of sugars and proteins as interfering co mpounds were carefully studied. The results obtained by the spectrophotomet ric method were compared with those found from the chromatographic method w hich was taken as reference method because it was free of interferences. Th e spectrophotometric method overestimates the phenolic content except in so me fruit samples with a high polyphenolic content. Sugars did not show inte rference whereas protein showed a high influence on the total phenols at th e concentration ranges found in the extracts. In green bean samples both me thods gave the same total phenols when the interference was masked. This fa ct could constitute an useful way to find the real content of phenolics in foods. (C) 2001 Elsevier Science B.V. All rights reserved.