Aggregation and degradation of plasticized wheat gluten during thermo-mechanical treatments, as monitored by rheological and biochemical changes

Different thermo-mechanical treatments were carried out on plasticized gluten samples using the rubber process analyser (RPA 2000) which allows to record changes in viscoelastic properties during sample treatment. Temperatures ranging from 90 to 150 °C were tested at two oscillatory strains (7%: linear domain; 70%: high deformation domain). Biochemical changes of gluten proteins during treatments were followed by SE-HPLC. Rheological and biochemical changes were found to be in good accordance and allow us to characterize two major phenomena: aggregation and degradation of wheat gluten proteins upon heating. A kinetic approach of both phenomena was carried out in order to determine the temperature dependency of both reactions with respect to applied strain. Strain was found to decrease the temperature dependency of modulus values, to moderately accelerate the gluten protein aggregation reaction, and to greatly accelerate the gluten thermal degradation.