Phenolic colorants obtained by enzymatic synthesis using a fungal laccase in a hydro-organic biphasic system

The oxidation of ferulic acid by laccase from Myceliophthora thermophila was followed with high performance liquid chromatography (HPLC) in aqueous and hydro-organic medium. Results achieved in this study showed that the enzymatic activity and the stability of the products greatly varied depending on the nature of the reaction medium. The oxidation of ferulic acid in a biphasic hydro-organic system (perfectly mixed) consisting of ethyl acetate and sodium-phosphate buffer resulted in intermediate stable yellow products. The organic solvent which decreased the activity of the laccase and the rate of non-enzymatic reactions led to the stability of these intermediate products. Compared to the aqueous medium, the biphasic hydro-organic medium presents significant advantages such as increased effectiveness in the prevention of browning and an increased solubility of the resulting colored products. Thereby, the biphasic medium facilitates the separation of these products which were soluble only in the organic phase of this system. (c) 2005 Elsevier Ltd. All rights reserved.