Total polyphenol content in food samples and nutraceuticals: antioxidant indices versus high performance liquid chromatography

Abstract

The total content of polyphenols and the antioxidant capacity have been estimated in various food and nutraceutical samples including cranberry, raspberry, artichoke, grapevine, green tea, coffee, turmeric, and other medicinal plant extracts. Samples have been analyzed by using two antioxidant assays ¿ferric reducing antioxidant power (FRAP) and Folin-Ciocalteu (FC)¿ and reversed-phase high-performance liquid chromatography (HPLC) focused on providing compositional fingerprints dealing with polyphenolic compounds. A preliminary data exploration by Principal Component Analysis (PCA) has revealed that HPLC fingerprints are suitable chemical descriptors to classify the analyzed samples according to their nature. Besides, chromatographic data have been correlated with antioxidant data using partial least squares (PLS) regression. Regression models have shown a good prediction capacity to estimate the antioxidant activity from chromatographic data, with determination coefficients (R2) of 0.971 and 0.983 for FRAP and FC assays, respectively.