In this paper, the complex coacervate phenomenon between milk proteins (MP) and chitosan of low (LC), medium (MC), and high (HC) molecular mass was studied. Factors influencing the optimal conditions of a coacervate formation such as chitosan molecular mass, protein-to-chitosan ratio, and pH variation were investigated. Using the results of Fourier-transform infrared spectroscopy (FTIR), particle size, zeta potential, and turbidity, a better insight into phase separation and formation of complex coacervate was obtained. Optimum complex coacervation occurred between milk proteins and LC at pH 4.6 and protein to chitosan ratio of 5:1, MC at pH 5.5 and ratio of 10:1, and HC at pH 6.7 and ratio of 15:1. Complex coacervate yields under optimal conditions for LC, MC and HC were 82%, 89%, and 97%, respectively. The findings of the present research can contribute to separating and purifying milk proteins using the complex coacervate method.

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