Investigation on the influence of high protein concentrations on the thermal reaction behaviour of β-lactoglobulin by experimental and numerical analyses

In this study, treatments at various temperature–time profiles were performed for β-lactoglobulin samples at different concentrations (50–70%) using a special rheometer as processing device. Rheological measurements, offline protein chemical analyses, and molecular dynamics analyses were performed to investigate the influence of high protein concentrations and treatment temperature on the denaturation and aggregation behaviour of β-lactoglobulin. Under these conditions, the degree of denaturation and aggregation decreased with increasing protein concentration. This corresponded to a strongly decreased diffusion and increased stability of exposed surface protein regions at high concentrations. Irreversible denaturation was observed for temperatures above 60 °C. Increasing thermal treatment intensity resulted in an increase of aggregation. Depending on the thermal treatment conditions, different protein–protein interactions were measured. By increasing the treatment temperature, the resulting aggregates were increasingly stabilised by covalent bonds. In addition to disulphide bonds, non-disulphide covalent cross-links were formed at temperatures above 100 °C.