The changes in the antioxidant properties of green and black tea extracts as a consequence of processing and storage conditions were
e ̈aluated through measurements of chain-breaking acti ̈ity, oxygen sca ̈enging capacity and redox potential. Pasteurisation and
storage as well as forced oxygenation in both tea extracts caused an increase in the optical density and a decrease in the reducing
power of the be ̈erages; both were accompanied by unexpected increases in the chain-breaking acti ̈ity of the be ̈erages. Simple model
systems containing catechin at a concentration similar to that found in the tea extracts were also considered to simulate the effects of
enzymatic browning in tea. Possible explanations for the chain-breaking acti ̈ity gain obser ̈ed in the tea extracts as a consequence of
processing were proposed.
