Interactions des protéines du lait et des oligoéléments

Abstract - Repartition of trace elements (Cu, Fe, Zn, and Mn) in milk between casein, whey proteins and non protein fraction was investigated. Casein bound about 95 % of manganese and zinc and 50-75 % of copper and iron; 15 to 33 % of copper and iron were present in non protein fraction and 18 to 33 % of iron in whey proteins fraction.
Addition of trace elements in milk modified the repartition especially for copper and manganese. Affinity of cas α_s1 and of cas β for copper and iron compared to affinity for calcium and magnesium and competition between calcium and iron for chelation of casein suggested that phosphoserine groups are element binding sites. Effect of orotical and citrate concentration on the repartition of trace element was studied. Citrate increased concentration of iron, manganese and copper in non protein fraction. Orotic acid only increased the copper content. The high degree of affinity of phosphoproteins. for trace element suggested to use phosphopeptides as chelators