EFFECTS OF HEAT-PROCESSING OF MILK ON VALIDATION CHARACTERISTICS OF THE CHARM AIM-96 AND DELVOTEST SP SCREENING TESTS

Two commercial screening tests (Charm AIM-96 and Delvotest SP) for the detection of antimicrobial resi- dues in milk were evaluated using samples of heat-processed milk. Heating to 85 °C for 5 min had no effect on detection limits for selected antimicrobial agents diluted in milk including penicillin, streptomycin, neomycin, Chlortetracycline, cloxacillin, chloramphenicol and sulphadiazine. Heat degradation of the interfering natura! inhibitors {lysozyme, IgG) re- sulted in considerable changes of almost all characteristics of validation of raw and heat-processed milk in both the tests. The value of true specificity increased from 96.55% for Charm AIM-96 and 90.62% for Deívotest SP to 100.0%. The most marked change occurred in the cutoff specificity which is decisive for correct scoring of milk with the concentra- tions of antimicrobial residues