β-Casein aids in the formation of a sodium caprate-induced β-lactoglobulin B gel

The effects of sodium caprate on the gelation of β-lactoglobulin B and a β-lactoglobulin B/β-casein mixture at ambient temperature were investigated using ultrasonic spectroscopy and rheology. A 12% β-lactoglobulin B solution gelled in the presence of 3.6% sodium caprate. Conversely, sodium caprate did not induce the formation of a gel when β-casein was in isolation, regardless of the protein concentration. Although a 6% β-lactoglobulin B/1.8% sodium caprate solution did not form a gel, a gel was formed when 6% β-casein was added to a mixture containing 6% β-lactoglobulin B and 3.6% sodium caprate. This gel showed comparable rheological properties to that of a gel containing 12% β-lactoglobulin B. The results clearly indicated that β-casein aids in the gelation of a β-lactoglobulin B/sodium caprate mixture, when the concentration of β-lactoglobulin B is insufficient to allow for gelation. It appears that β-casein self-aggregation is also inhibited. Therefore, it could be concluded that β-casein can be used as a texture modifier for β-lactoglobulin gelation induced by sodium caprate.