30. Observations on the Copper and Iron Content of Milk and other Dairy Products

Abstract

The range of the copper and iron content of 80 samples of fresh, pasteurised and sterilised milk are given. Examples of investigations on the point of entry of copper into milk during processing are given. As a minimum limit, 1·5 p.p.m. of copper in milk can be expected to produce “oiliness” in milk. The copper content of dried milk is usually normal but the iron content is increased above that expected from the iron content of fluid milk. Cheese made in copper vessels has a high copper content; and the iron content of cheese is variable. Butter contains on an average about 0·5 p.p.m. of copper and 1 p.p.m. of iron. Factory made butter invariably contains more iron and copper. The more a milk product is processed, the greater is the contamination with heavy metal. An example of determining the amount of blood in milk by a determination of the iron content is given.