Review of methods to determine chain-breaking antioxidant activity in food

The beneficial influence of many foodstuffs and beverages including fruits, vegetables, tea, red wine, coffee, and cacao on human health has been recently recognized to originate from the chain-breaking antioxidant activity (AOA) of natural polyphenols, a significant constituent of the above products. For this reason, the dietary value of such products is determined to a large extent by their AOA. The latter stimulated the development of effective and reliable methods for determining AOA. Although the kinetic approach provides the basis of the majority of these methods, only a few of them have been analyzed from the viewpoint of chemical kinetics. This review is intended to close down this gap, at least partly. The most popular methods for determining chain-breaking AOA of food are considered with the aim to estimate their reliability and limitations. The main requirements imposed on these methods have been suggested. The main attention has been paid to the repeatability of the data obtained. Along with the methods that are currently popular among researchers working in food chemistry and biomedical sciences, perspectives of the application of the methods used to studying industrial antioxidants have also been considered. The review consists of two main sections. In the first general section, definitions of the main parameters used to characterize AOA are given and the kinetic basis of the methods applied is considered in some detail. The second section is devoted to particular methods including some technical details. In conclusion the data on AOA obtained by various methods are correlated with each other.