Effects of heat-processing of milk on validatin characteristics of the Charm AIM-96 and Delvotest SP screening tests
2000
Schlegelova, J. | Rysanek, D. (Vyzkumny Ustav Veterinarniho Lekarstvi, Brno (Czech Republic))
Two commercial screening tests (Charm AIM-96 and Delvotest SP) for the detection of antimicrobial residues in milk were evaluated using samples of heat-processed milk. Heating to 85 deg C for 5 min had no effect on detection limits for selected antimicrobial agents diluted in milk. Heat degradation of the interfering natural inhibitors (lysozyme, IgG) resulted 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 Delvotest SP to 100.0 %. The most marked change occurred in the cutoff specificity which is decisive for correct scoring of milk with the concentrations of antimicrobial residues MRL (maximum residue limit) as negative. Heat processing reduced the number of false positive samples detected by Delvotest SP by up to 18.21 % (P0.01). The characteristics of "cutoff sensitivity" were unaffected. Both raw and heat-processed milk samples containing residues of antimicrobial agents at levels corresponding of MRL were scored correctly by both the tests.
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