Transition metal ions in black tea: an electron paramagnetic resonance study

Abstract

Tea (Camellia Sinensis) is the most widely consumed beverage in the world and is known to have therapeutic, antioxidant and nutritional effects. It contains dimeric flavanols and polyphenols which are known as the most important organic compounds in tea infusions, and can make strong and stable complexes with metal ions. In this study, we carried out a series of electron paramagnetic resonance experiments on well-known paramagnetic transition metal ions, namely Mn2+, Fe3+, Cu2+, VO2+, and Cr3+ doped in black tea cultivated along the shore of Black Sea, Turkey, to see the effects and structures formed.