Polyphenol analyses

Chalcones and dihydrochalcones have been reported in a restricted number of foods (Robards and others 1999 Tomas-Barbcran and Clifford 2000). Chalconaringenin occurs in tomato skin, but the acid extraction conditions of the usual polyphenol analyses convert the chalcone to the corresponding flavanone (naringenin) in the tomato. The most common dihydrochalcones found in foods are phloretin glucoside (phloridzin) and phloretin xylogalactoside, which are characteristic of apples (see Table 2.2) and derived products such as apple juice, cider, and pomace (Robards and others 1999 Tomas-Barbcran and Clifford 2000). 

Wrolstad, R.E. and Durst, R.W. 1998. Use of anthocyanin and polyphenolic analyses in authenticating fruit juices. In Proceedings of Fruit Authenticity Workshop, pp. 79-86. Montreal, Canada, September, 1999. EUROF1NS Scientific, Nantes, France. 

Polyphenol Analyses. Skin and seed extracts were prepared as described elsewhere (4,15). Flavonol and anthocyanin composition of grape skin extracts and wines were determined by direct reversed-phase HPLC analysis with diode array detection. The chromatographic conditions were the same as described earlier (16) but the formic acid concentration in the elution solvents was raised to 5% to improve anthocyanin resolution. Quantitations were based on peak areas, using mdvidin-3-glucoside (at 530nm) and quercetin-3-glucoside (at 360 nm) response factors, respectively, for anthocyanins and flavonols. 

Extensive reviews of analytical methods for anthocyanins (Francis, 1982 Jackman et al., 1987b Strack and Wray, 1994) and other flavonoids (Williams and Harbome, 1994) as well as phenolic acids (Herrmann, 1989) have been published. In these reviews, extraction procedures, methods for fractionation of groups of polyphenols and the identification and quantification of individual components are presented. Here, a brief presentation of more recently published methods for grape and berry polyphenolic analyses is given with respect to their relationship to antioxidant activity and health benefits. 

Escribano-Bailon M and Santos-Buelga C. 2003. Polyphenol extraction from foods. In Santos-Buelga C, Williamson G, editors. Methods in Polyphenol Analysis. Cambridge The Royal Society of Chemistry,... 

Wolfender, J.-L., Ndjoko, K., and Hostettmann, K., Application of LC-NMR in the structure elucidation of polyphenols, in Methods in Polyphenol Analysis, Santos-Buelga, C. and Williamson, G., Eds., Royal Society of Chemistry, Cambridge, 2003, chap. 6. 

Santos-Buelga, C. and Williamson, G., Eds., Methods in Polyphenol Analysis, Royal Society of Chemistry, Cambridge, 2003. 

Cheynier, V. and Fulcrand, H., Analysis of proanthocyanidins and complex polyphenols. In Methods in Polyphenol Analysis (eds C. Santos-Buelga and G. Williamson), Royal Society of Chemistry, London, 2003, p. 282. 

Presents state-of-the-art methodologies for polyphenolic analysis, bioavailability, and metabolism... 

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