Modelling the reaction kinetics of β-lactoglobulin and κ-casein heat-induced interactions in skim milk

Levels of native beta-lactoglobulin (β-lg) in heat-treated milk are often used as a measure of quality deterioration. Most kinetic studies to date on β-lg denaturation have been simplified to a single step model, which limits its application in various processing conditions. Furthermore, this denaturation of β-lg is only an initial stage in a series of interactions to take place. In this work, a multistep model for the denaturation of β-lg and its subsequent reaction with κ-casein was developed. This model was used to rationalize the concentrations of native β-lg and κ-casein determined from HPLC. Notably, this model provides a clear account of the influence of β-lg on the loss of micelle-bound κ-casein. The various reaction rates reveal reactions are limited by the rate at which sulfhydryl-disulfide reactions connect proteins while the effect of intermolecular forces is minimal. •β-lactoglobulin denaturation mechanism was expanded to three steps: dimerization, polymerization and reaction with κ-casein.•κ-casein dissociation is predictable from the denaturation of β-lactoglobulin.•The model unifies the two β-lactoglobulin denaturation rate-limiting regimes with a smooth curve.