Formation of soluble complexes of milk proteins- soluble fraction of Iranian native gums and investigation of the effect of biopolymers concentration on phase behavior of systems

Electrostatic interaction between proteins and negatively charged polysaccharides leads to formation of stable colloidal system or causes complex coacervation. Therefore, in this study phase behavior of the mixtures of 0.4% milk proteins (sodium caseinate or whey protein isolate) with soluble fraction of tragacanth (up to 1%) or soluble fraction of Persian gum (up to 2%) as a function of pH (2–7) was investigated, in order to obtain appropriate protein:polysaccharide ratio to formation of soluble complexes in a wide range of pH. According to the results, the mixtures of sodium caseinate–soluble fraction of Persian gum, sodium caseinate–soluble fraction of tragacanth, whey protein isolate–soluble fraction of Persian gum and whey protein isolate–soluble fraction of tragacanth were soluble complexes at the whole pH range at the ratio of 0.4:0.6, 0.4:0.6, 0.4:2 and 0.4:1, respectively. Moreover, it was found that enhancement of total biopolymer concentration (at a same ratio) had no effect on the phase behavior of complexes. In addition, evaluation of the phase behavior of the mixture of milk proteins–alcohol-insoluble fraction of soluble part of native gums illustrated that both alcohol-insoluble and soluble fractions probably have impact on stability of complexes at mentioned ratios.