The stabilization mechanism of acidified milk drinks induced by carboxymethylcellulose

Abstract

In the present work carboxymethylcellulose (CMC) was used as a stabilizer to avoid the flocculation of milk proteins in acidified milk drinks. The particle diameter and ζ-potential evolu- tion during acidification of casein micelles in CMC were studied. The experimental results indicate that the adsorption of CMC takes place at and below pH 5.2 and that electrosorption may be the driving force for the adsorption of CMC onto the casein micelles. The stability of acidified milk drinks induced by CMC could be explained presumably by steric stabilization caused by the an- chor of CMC onto the casein micelles' surface rather than electrostatic repulsion. Above pH 5.2 phase separation of the casein/CMC mixture corresponding to thermodynamic incompatibility was found at high CMC concentration, while below pH 5.2 the adsorption of CMC led to either sta- bilization or bridging among casein micelles depending on the CMC concentration. In addition, the non-adsorbed CMC (serum CMC) increased the viscosity of the serum and thus contributed to preventing casein micelles from precipitating. acidified milk drink / carboxymethylcellulose (CMC) / casein micelle / electrosorption / stability