Milk protein suspensions enriched with three essential minerals: Physicochemical characterization and aggregation induced by a novel enzymatic pool

Structural changes of casein micelles and their aggregation induced by a novel enzymatic pool isolatedfrom Bacillus spp. in the presence of calcium, magnesium or zinc were investigated. The effect of cationson milk protein structure was studied using fluorescence and dynamic light scattering. In the presenceof cations, milk protein structure rearrangements and larger casein micelle size were observed. Theinteraction of milk proteins with zinc appears to be of a different nature than that with calcium ormagnesium. Under the experimental conditions assayed, the affinity of each cation for some groupspresent in milk proteins seems to play an important role, besides electrostatic interaction. On the otherhand, the lowest aggregation times were achieved at the highest calcium and zinc concentrations (15 mMand 0.25 mM, respectively). The study found that the faster the aggregation of casein micelles, the lesscompact the gel matrix obtained. Cation concentrations affected milk protein aggregation kinetics andthe structure of the aggregates formed.