Both peaks were dialysed through a 12-kDa membrane and analysed by C18 reverse phase HPLC with diode array detection before and after tryptic hydrolysis. Analysis of chromatograms revealed that coloured compounds were present only in peak 2 and were better detectable after proteolysis. It is concluded that, in the gluten-glucose system, coloured low molecular weight molecules became entrapped in the high molecular weight polymers formed by gluten proteins and that trypsin treatment of gluten favours the release of the coloured compounds.