Effects of flour chlorination on soft wheat gliadins analyzed by reversed-phase high-performance liquid chromatography, differential scanning calorimetry and fluorescence spectroscopy

Chlorinated soft wheat flours produce better quality cakes. In this study, changes in surface hydrophobicity of gliadins due to flour chlorination were analyzed. Results obtained from RP-HPLC of gliadins showed intervarietal differences, but intravarietal differences in the gliadin patterns of chlorinated and unchlorinated flours were difficult to discern because of the large number of peaks eluted. However, three-dimensional plots of retention time, wavelength and absorbency showed differences among gliadin patterns of unchlorinated and chlorinated flours within a variety, suggesting conformational changes and consequently alteration in hydrophobicity of gliadins due to chlorination. The DSC analyses of gliadins extracted from unchlorinated and chlorinated flours showed higher denaturation peak transition temperatures (Td) and lower enthalpies of transition (ΔH) in some varieties, indicating hydrophobicity and conformational changes. Fluorescence spectroscopy measurements with an extrinsic probe, 1-anilino-8-naphthalene sulfonic acid (ANS), showed increases in hydrophobicity of gliadins from chlorinated flours, confirming conformational changes in gliadins due to chlorination.