Acid-induced gelation behavior of sonicated casein solutions.

Casein gels were made from solutions sonicated by 24 and 130 kHz ultrasounds for 0, 60 and 120 min, followed by acidification with glucono-delta-lactone at 30 degrees C. The dynamics of gel formation were studied using rheological methods and microstructure of gels was monitored using scanning electron microscopy. Sonication postponed the gelation point to a lower pH value and increased the elasticity of freshly formed gels. It also resulted in gels with a more interconnected structure and smaller non-distinguishable particulates. This structure was especially dominant for the gel made from the solution already sonicated for 120 min.