Transferof 226Ra, 85Sr and 137Cs from milk to milkproducts

Summary  Transfer of ²²⁶Ra, ⁸⁵Sr and ¹³⁷Cs from cow and sheep milk to various Syrian dairy products has been evaluated. Dairy products include Kashkivan cheese, braided cheese, Haloom cheese, Sircassian cheese, liquid cheese, native cheese, cottage, thick yogurt, butter and milk cream. The results showed that the percentage of ²²⁶Ra, ⁸⁵Sr and ¹³⁷Cs transferred from cow milk to milk cream (P_t=food processing retention factor′processing efficiency′100%) has reached 32%, 16% and 7%, respectively. Butter and liquid cheese were found to have the lowest percentage of transferred  226Ra, ⁸⁵Sr and ¹³⁷Cs. Most of the obtained P_t values of the studied radionuclides in thick yogurt were relatively low in spite of the high processing efficiencies of thick yogurt. Moreover, the transfer, P_t, of the studied radionuclides from cow milk to the prepared cheese was higher than those values determined for sheep milk. This is due to differences in chemical compositions of each type of milk. On the other hand, the treatment of Native cheese, most commonly consumed cheese in Syria, with different concentrations of NaCl solutions showed that ¹³⁷Cs was completely removed from cheese soaking in 5% NaCl solution (soaking time of 48 hours), while 40% of ²²⁶Ra and 80% of ⁸⁵Sr were also decontaminated using 0-2.5% NaCl solutions and soaking time of 48 hours. Based on the obtained results, industrialization processes of the dairy products that resulted the removal of radionuclides have been identified.