Method of casein obtaining from skimmilk using oligochitosans

Abstract

The interaction of milk proteins and oligochitosans is based on formation of electrostatic complex between negatively charged casein micelles and positively charged polysaccharide groups. At low concentrations of oligochitosans, partial interaction with milk proteins occurs. Maximum protein coagulation (90 %) is achieved in equivalence zone at the concentration of oligochitosans: 45.3 kDa-0.88×10-4 M; 25.4 kDa-1.57×10-4 M; 7.7 kDa - 5.19×10-4 M; 1.5 kDa-26.67×10-4 M. In these concentrations, taking into account the molecular weight and degree of deacetylation of oligochitosans, the total content of protonated amino groups is equal 2.4×10-4 M. When t protein content in skimmed milk is 3.0 % - 3.2%, oligochitosans of any molecular weight and degree of deacetylation can be used for casein coagulation, important that the final concentration of amino groups should be 2.4×10-4 M. It was determined that the use of the studied samples of oligochitosan allows to obtain coacervate where 1 g of oligochitosan binds 6.0 - 6.2 g of milk proteins.