The aim of this work was to determine the effect of an extrusion processing on chemical scores of a nutritive value of protein and content of lysinalanine in caseinates obtained by extrusion. It was found that during production of caseinates takes place decreasing of cystine and lysine contents. Changes of amino acids content resulted in significant decrease of chemical score (CS) value and the essential amino acids index (EAAI). The changes also caused an increase of lysinalanine content against to raw material (acid casein).