The Journal of

Introduction: Awareness and concern about soil contamination with metals and their effects on the food chain are increasing. Cereal consumption is one of the major sources of metal exposure which soybean may accumulate more toxic metals than other crops.
Method: Three metal elements including Zn, Cd, and Ni were measured in soy products. First, soymilk and soy cheese (tofu) were prepared by common methods, and then the digested samples were analyzed by ICP-OES. The carryover of metals in different methods was determined.
Results: The soymilk prepared by rapid method showed higher Zn content (P<0.05). Furthermore, among all types of cheeses, Zn content of calcium cheese obtained from all three methods was significantly higher (P<0.05). Ni content of soymilk and soycheese of the rapid method was higher than the other methods (P<0.05). In the traditional method large quantities of Ni was removed by soaking  seeds and okara. Measurements showed high Cd content in soymilk and soy cheese in the rapid method (P<0.05); however, Cd content of other methods was lower than expectation.
Conclusion: According to the results the method of soybean production, soy soaking, the type of clot  and the tendency of elements toward different parts of the product can have a significant effect on the amount of transfer and removal of the metals.