Influence of thermal processing on the physicochemical properties of bovine lactoferrin

Abstract

Aqueous solutions of lactoferrin (LF) were subjected to thermal processing (72, 80, 85, 95 °C for 15 s) using a rheometer. Despite the low protein concentration and low ionic strength of the LF solutions, analyses post-processing revealed the presence of heat-induced, covalently-linked, protein aggregates. Aggregation was accompanied by increased surface hydrophobicity and zeta-potential and changes to the secondary structure of the protein, including reduction in the proportion of alpha helix domains coupled with increased intermolecular beta sheet structures. The native red colour of the protein was lost upon thermal processing, not attributable to the release of LF-bound iron. Micro-differential scanning calorimetry showed LF to be irreversibly denatured on heating with endotherms observed at 58.7 °C (apo-LF) and 89.6 °C (holo-LF). Thermal processing at 72–95 °C resulted in irreversible changes to the structural and physicochemical properties of bovine LF, whereby the lowest heating intensity had the least impact on LF structure.