Qualitative test for the detection of extraneous thiocyanate in milk

Thiocyanate is one of the three components of lactoperoxidase system for preserving the milk under the conditions where chilling facilities do not exist due to economic and technical reasons. In 1988, International Dairy Federation (IDF) has recommended the levels and the code of practices for the application of LP-system. As the excessive use of thiocyanates beyond the recommended limits can lead to human health hazards, its rapid detection in milk at the reception dock of dairy, where milk is tested for quality before its acceptance or rejection, is necessary. For simple and rapid detection of added thiocyanates in milk, two types of qualitative tests have been developed in this study, of which one is applicable directly to milk and the other is applicable to TCA filtrate of milk. The results of the test reveal that as low as 0.6 ppm of added thiocyanate (equivalent to 1 ppm of potassium thiocyanate) can be detected. The orange to orange-red color obtained in the test solution can be considered the basis of rejecting milk assuming that it has added levels of thiocyanate.