The influence of milk processing upon the binding of iron to various milk protein fractions

Fortification of food with iron has been of great interest to nutritionists because anemia is the most prevalent nutritional problem throughout the world. In spite of the fact that milk and milk products are widely available, they are low in natural iron content. Because of the significance of milk in our diet, it is an appropriate food for for-tification with iron. Pasteurization and homogenization are the standard dairy industrial processes. The purpose of this study was to investigate the effect of pasteurization and homogenization on the binding of added iron to milk proteins. Pasteurization was carried out at 62.8 C for 30 min and the pasteurized milk was homogenized through a two stage commercial homoge-nizer. The effect of processing was determined by measuring iron content in casein, whey proteins, beta-lactoglobulin, proteose-peptone, and fat-globule membrane protein. The data indicated that most of added iron was recovered in the skimmilk portion. Pasteurization changed only the binding capacity of whey proteins. Whey proteins from raw milk bound more added iron than that from pasteurized milk. Homogenization increased the binding capac-ity of all milk proteins. The order of decreasing binding capacity of milk proteins (microgram Fe/g protein) from raw or pasteurized milk was as follows: fat-globule membrane protein, rennin-coagulated casein, proteose-peptone, acid-precipitated casein, and whey proteins. The order of binding capacity in homogenized milk (microgram Fe/g protein) was as follows: rennin-coagulated casein, fat-globule membrane protein, acid-precipitated casein, proteose-peptone, and whey proteins.