Phytochemicals of foods, beverages and fruit vinegars: chemistry and health effects.

Plant-based foods and food ingredients provide a wide range of phytochemicals and antioxidants that render their beneficial health effects through a number of mechanisms. The presence of phenolics in different plant materials and beverages depends on the source material which dictates the type and quantity present. In addition, processing of raw materials, including fermentation, may alter the chemical nature and efficacy of their phenolic constituents. While vinegar has traditionally been used for food preservation and as a seasoning, more recently, fruit vinegars with different sensory characteristics have appeared in the marketplace. In addition to acetic acid, fruit vinegars often contain citric, malic, lactic, and tartaric acids and may also include phenolics, some of which are produced as a result of fermentaion. The beneficial health effects of fruit vinegars may in part be related to the process-induced changes in their phenolics and generation of new antioxidative phenolics during fermentation.