Detection of formalin in Ras cheese during the ripening period by different methods

A total of 120 samples of fresh Ras cheese collected from different localities at El-Behaira Governorate were examined for the presence of formalin by Hehner's, flame and chromotropic acid tests, then 10% of the positive samples [7] were stored and tested during ripening period up to 90 days. Most of cheese samples [58.33%] contained formalin detected by flame and chromotropic acid tests, but 41.67% of the tested samples were positive by Hehner's method. The chromotropic acid test is an accurate, rapid, simple, highly specific, sensitive, inexpensive, easy and quantitative method for detection of formalin, especially during ripening period and with low concentrations in routine controls. There were great variations in formalin content in different samples depending upon the cheese maker. Also, the quantities of formalin in tested samples of Ras cheese were not changed during ripening, whereas it revealed dangerous and highly toxic effect due to daily consumption of the cheese, and at a long continuous intake of formalin it might be harmful. It can be recommended that formalin must not be added to the milk used in manufacturing Ras cheese at any level