Oxidation of phenolics can be carried out via oxygenation under alkaline condition (Balange and Benjakul, 2009) or via enzymatic reaction. Laccase (E.C.1.10.3.2, p-benzenediol:oxygen oxidoreductase) is an oxidoreductase able to catalyse the oxidation of various aromatic compounds (particularly phenols) with the concomitant reduction of oxygen to water (Duran et al., 2000). A phenolic substrate is subjected to a one-electron oxidation, giving rise to an aryloxyradical. This active species can be converted to a quinone in the second stage of the oxidation. The quinone and free radical product undergo non-enzymatic coupling reactions, leading to polymerisation (Duran and Esposito, 2000). Laccase
has also been reported to catalyse polymerisation of certain peptides and proteins (Mattinen et al., 2005;
2006)