Shear, heat and pH induced conformational changes of wheat gluten – Impact on antigenicity

• Gluten conformation changed with various pH, temperature and shear.
• At pH 3, up to 90 °C antigenicity was reduced to a third of its original value.
• At pH 5 and 7 antigenicity declined only at 100 °C.
• Shear alone had no effect on antigenic reactivity of gluten except at pH 7 and 100 °C.

Processing can induce conformational changes of food proteins depending on the conditions used that may affect their antigenicity. This study investigated the effect of pH (3, 5, 7) temperature (80, 90, 100 °C) and shear (500, 1000, 1500 s−1) on the conformational changes (surface hydrophobicity, FTIR, SDS–PAGE and thiol content) of gluten in relation to its antigenicity (determined by Enzyme-linked Immunosorbent Assay). Overall, at pH 3, up to 90 °C, conformational changes and possible burial of some antigenic hydrophobic residues resulted in reduction of antigenicity to one-third that of control. Further heating to 100 °C caused increase in antigenicity due to exposure of some hidden epitopes. However, at pH 5 and 7, the antigenicity declined only at 100 °C due to modification in thiol content and related structural changes causing destruction and/or masking of some epitopes. Shear alone had no effect on antigenicity of gluten but could have a synergistic influence at pH 7 and 100 °C.