1. Laboratoire de chimie agro-industrielle, Institut National Polytechnique, Ecole Nationale Supérieure de Chimie de Toulouse, 118 route de Narbonne, 31077 Toulouse cedex 4, France.
2. Corresponding author. Phone: +33(0)562885720. Fax: +33(0)562885730. E-mail: vtropini@ensct.fr
3. Institute for Agrotechnological Research (ATO-DLO), Division Industrial Proteins, Bornsesteeg 59, PO Box 17, 6700 AA Wageningen, The Netherlands.