The effects of high-intensity ultrasound on the structural and functional properties of α-Lactalbumin, β-Lactoglobulin and their mixtures

In this study, the structural and functional changes of pure and 3:1 mixtures of β-Lactoglobulin (β-LG) and α-Lactalbumin (α-LA), the most abundant whey proteins in milk were studied after sonication at 20 kHz (31 W) for up to 60 min. The reactive thiol content and surface hydrophobicity of pure β-LG increased continuously during sonication, suggesting an unfolding of the dimer structure. Minor secondary and tertiary structural changes were also observed by circular dichroism. The α-LA protein appeared to be more strongly affected by sonication, with significant increases in surface hydrophobicity. The results suggest that sonication has a greater effect on α-LA than on β-LG, which means that the properties of their mixture differ substantially from that of either protein in isolation.