A process is provided for preparing (1) a first composition obtained by extracting a plant material with a single phase mixture of water and at least a first organic solvent under agitation so as to obtain a first extract rich in polyphenol oligomers, wherein the first composition is the first extract, and (2) a second composition obtained by extracting at least a portion of the first extract with a biphasic mixture of water and at least a second organic solvent under agitation so as to obtain a second extract rich in polyphenol monomers, dimers, and trimers, wherein the second composition is the second extract. Food products, mendicants, and cosmetics containing the first composition or the second composition are also provided.
