Dynamic rheology of renneted milk gels containing fat globules stabilized with different surfactants

Anhydrous milk fat was emulsified with alpha s1-CN (casein), alpha s2-CN, beta-CN, kappa-CN, alpha-lactalbumin, beta-lactoglobulin, Tween 80, or phosphatidylcholine to produce a 30% fat cream in a 0.1 M imidazole pH 7 buffer. The creams were mixed with skim milk to yield a fat content of 3.4% and the viscoelastic properties of the recombined milks clotted with chymosin were measured. Recombined milk containing globules coated with the more amphipathic and phosphorylated alpha s2-CN and beta-CN clotted faster but gel firmness increased more slowly and weaker gels were formed. Gel firmness increased more rapidly for milks containing globules coated with of alpha s1-CN and kappa-CN that possess more uniformly distributed hydrophobic domains.