Photomicrographs of control and pretreated wheat bran. Images of unstained bran (A-C) and at higher magnification (D-I) showing colouration due to Maillard reactions in the pretreated materials. Under UV, lignified native bran tissues autofluoresce blue at neutral pH (J) whilst at alkaline pH, cinnamic acid and related moieties autofluoresce green (M). However in the HT samples, this autofluorescence is visibly reduced. Bars: 1 mm (A-C); 0.5 mm (D-L); 100 μm (G-O).