Physicochemical Properties of Natural Casein Protein Concentrate and Structuring Concentrate in Mayonnaise Production

Abstract

When studying the behavior of milk proteins in model systems, it is necessary
that the research conditions correspond to the real processing conditions of the
modeled systems into food products. Since our research involves the use of milk
proteins in the production of emulsion products, which mainly have an acidic
environment, the solubility of milk proteins was studied precisely in this range. The
dependence of the viscosity of CMP (presumably Casein Micellar Protein) and WPC
(Whey Protein Concentrate) on pH is characterized by a maximum in the region of
pH = 10 and pH = 8, respectively, while the dependence of the viscosity of CMC
(Casein Micellar Concentrate) on pH increases more than 10 times in the region of
pH = 9. When the pH is lowered to 5 and below, CMC precipitates, and this
corresponds to the pH range of 4–5 for CMC. In this pH range, viscosity
measurements of CMC solutions were impossible due to precipitation. To the right of
this region, the viscosity of the solutions increases regularly, which is associated with
the ionization of negatively charged carboxyl groups of casein. The decrease in
viscosity to the right of pH = 9 is apparently due to the specific adsorption of Na+ on
negatively ionized COO– groups, which leads to a decrease in the effective charge of
these groups and, as a consequence, to a decrease in the size of the macroion and a
decrease in the viscosity of their solutions.