Several in vitro studies have shown that polyphenols are the major contributors with respect to the total antioxidant activity of the majority of fruits and vegetables. Over polyphenolic molecules have been identified and can be classified into flavonoids and non- flavonoid phenolics. Certain authors consider (poly)phenols to be all secondary phytochemicals that have at least two phenol subunits. However, (poly)phenols are also defined as all secondary metabolites possessing an aromatic benzene ring that is substituted by at least two hydroxyl groups, including their functional derivatives (reviewed by Bouayed, 2010). Moreover, in the classification given by Manach et al. (2004),.
