Stability of β-lactoglobulin/micellar casein mixtures on heating in simulated milk ultrafiltrate at pH 6.0

The stability of β-lactoglobulin (β-lg)/micellar casein (MC) mixtures was examined on heating at pH 6.0 in increasing levels of lactose-free simulated milk ultrafiltrate (SMUF). Heated β-lg associated with MC to form stable particles (up to 771 nm in size in SMUF × 0.5). Higher levels of SMUF induced reductions in the charge on particles, resulting in greater aggregation and precipitation. Results indicated that the nonthiol-containing α_s1- and β-casein fractions showed greater interaction with β-lg on heating than the thiol-containing fractions (α_s2-casein and κ-casein). Casein proteins and their fractions have potential application in the development of heat-stable dairy-based beverages.