Rapid determination of polyphenols and vitamin c in plant-derived products.

J Agric Food Chem. 2005 Mar 9;53(5):1370-1373. Related Articles, Links

George S, Brat P, Alter P, Amiot MJ.

Centre Technique de la Conservation et des Produits Agricoles (CTCPA), Site Agroparc, F-84911 Avignon Cedex 9, Centre de Cooperation Internationale en Recherche Agronomique pour le Developpement (CIRAD), Departement FLHOR, TA50/16, F-34398 Montpellier Cedex 5, and Human Nutrition and Lipids, Faculte de Medecine, UMR U-476 INSERM (National Institute of Health and Medical Research)/U-1260 INRA (National Institute for Agronomic Research), 27 Boulevard Jean Moulin, 13385 Marseille Cedex 05, France.

Polyphenols, widely spread in our diet by the consumption of plant food products, are commonly determined using Folin-Ciocalteu reagent that interacts with other different reducing nonphenolic substances and leads to an overestimation of polyphenol content. In this paper we report an optimized Folin-Ciocalteu method to specifically determine the contents of total polyphenols and vitamin C. After the optimal conditions for the colorimetric assay were set, solid-phase extraction (Oasis HLB (hydrophilic-lipophilic balance)) was carried out to eliminate the water-soluble reducing interferences including vitamin C. Colorimetric correction was thus performed by subtracting interfering substances contained in the water washing extract from the raw extract. Moreover, vitamin C present in the water washing extract can be destroyed by heating and thus colorimetrically deduced. This procedure was set up with synthetic solutions and validated on different extracts from fruit products.