Antioxidant capacity of herbal teas from Bulgarian market

The antioxidant capacity of numerous plant species with medical potential, as well as the tea plant (Camellia sinensis L.) have been extensively studied. On the other hand, such data for herbal tea blends, taken directly from the market are scarce. The aim of our study was to evaluate the antioxidant capacity and phenol content of tea and herbal tea blends available on Bulgarian market and to assess Haberlea rhodopensis leaves as a potential ingredient of herbal teas. We applied two methods to evaluate the antioxidant capacity - the Ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays, after a two step procedure of processing and extraction of water-soluble and lipo-soluble antioxidants. We did not find a direct relationship between the content of phenols and the antioxidant capacity of the studied herbal teas. The commercial samples of Camellia sinensis L. (North Vietnam cultivation, Tikanium, Green tea) had the highest antioxidant capacity. According to TEAC and FRAP assay Common St John's wort, Oregano, and Garden sage showed antioxidant capacity close to that of Green tea. Maximum antioxidant capacity and, hence maximal health benefits could be obtained from ca. 30 min infusions of Roselle tea and especially Haberlea leaves. This makes cultivated Haberlea rhodopensis a valuable potential ingredient for new blends of herbal tea with high antioxidant capacity.