Kinetics of denaturation and aggregation of highly concentrated β-Lactoglobulin under defined thermomechanical treatment

The influence of thermomechanical treatment (temperature 60 °C – 100 °C and shear rate 0.05 s⁻¹ – 50 s⁻¹) on the denaturation and aggregation of β-Lactoglobulin at high concentrations (50 % – 70 %) was investigated. While denaturation and aggregation reaction rate decreased at higher concentrations, a combination of heat and mechanical treatment resulted in an increase in reaction rates and consequently, in higher degrees of non-disulfide covalent bond aggregation. The kinetic parameters were determined by non-linear regression. Denaturation (combined effect of unfolding and aggregation) and covalent bond aggregation were found to follow 2.15 and 1.7 order kinetics, respectively. At the investigated conditions, the activation energy calculated for the denaturation and covalent bond aggregation reaction ranged from 25 to 283 kJ mol⁻¹. Although the activation energy for the denaturation and aggregation reactions decreases with increasing shear rate, it was found that the mechanical treatment mainly affected the reactions at high temperatures, probably due to the increased molecular motion.