pH-induced physicochemical modifications of native phosphocaseinate suspensions: Influence of aqueous phase

Abstract

pH-Induced physicochemical changes and rennet coagulation times of casein micelle suspensions have been studied with native phosphocaseinate powder dissolved in water, 0.1 mol L-1 NaCl and milk ultrafiltrate. An increase in ionic strength between water and NaCl led to higher diffusible calcium and phosphorus, to greater micelle voluminosity and to greater casein and mineral solubilization during acidification. Dissolution of the phosphocaseinate in ultrafiltrate resulted in physicochemical properties very close to milk. The acidification process can be divided into five successive steps. Relations between physicochemical changes are discussed, together with the reduction of rennet coagulation time with pH and ionic strength reduction.