摘要：Fourty-two samples of butter, 13 of powdered milk, 45 of cheese, 37 of cheese type foods, containing various kinds of foodstuffs, and 2 of vegetable cheese (substitutes) were collected from domestic and foreign markets, and analyzed regarding their contents of nickel and other heavy metals. 1) In butter, nickel was only 0.04ppm or less in a few samples, and none in the rest. The average content of iron was 0.23 and 0.30ppm in domestic and foreign butter, and 0.27 and 0.74ppm in domestic and foreign reduced fat butter, respectively; while that of copper was 0.03, 0.02, 0.02 and 0.07ppm, respectively. On the contrary, the average content of nickel, iron and copper in raisin butter was 0.04, 6.91 and 1.08ppm, respectively, suggesting that raisins contain much more iron and copper than butter. 2) In powdered milk, nickel was only 0.01ppm in one of the skimmed products, and non in the rest. The average content of iron and copper was 1.74 and 0.29ppm in the skimmed type and 2.00 and 0.24ppm in the whole type, respectively. 3) In cheese, nickel was only 0.15ppm or less in almost all of the samples except for one type of the foreign natural cheese (1.19ppm). The average content of iron was 0.99 and 1.34ppm in domestic and foreign natural cheese, and 1.52ppm in processed cheese, while that of copper was 0.16, 0.26 and 0.23ppm, respectively. The content of copper was correlated to that of protein for natural or processed cheese, but such a correlation was not observed between iron and protein. On the contrary, vegetable cheese, not containing any milk component, contained 0.10ppm nickel, 23.0ppm iron and 2.82ppm copper, on the average. 4) The analytical results on heavy metals in cheese type foods suggested that iron in mushrooms, iron and copper in cherries, raisins or crabs, as well as the 3 metals in chocolate or nuts, could cause an increase in each of the metal contents in the product. 5) No sample found any lead and arsenic.
