Heat-induced aggregation kinetics of potato protein - Investigated by chromatography, calorimetry, and light scattering

Abstract

In this study, the heat-induced aggregation behavior of patatin rich potato protein isolate (PPI) was investigated by reversed-phase high-pressure liquid chromatography (RP-HPLC), differential scanning calorimetry (DSC), and dynamic light scattering. It could be shown that aggregation already occurs at low temperatures, despite low degrees of unfolding. The unfolding temperature, determined by DSC, coincided with a change in the reaction kinetics, which is determined by the unfolding step below a critical temperature up to the point, where the proteins are completely unfolded. The reaction rate k as a function of the absolute temperature T is then determined by diffusion of unfolded proteins forming aggregates. This change can be visualized in the Arrhenius diagram by a change of the slope of the relationship k ∼ 1/T. A change in pH from 7 to 6 shifted the critical temperature towards higher values and resulted in larger aggregate sizes, due to reduced electrostatic repulsion.

Keywords: Arrhenius; Degree of denaturation; Dynamic light scattering; Patatin; Plant protein; Reaction kinetics; Thiol.