| Abstract [eng] |
The problems of determining residues of inhibitors in raw milk, i. e. selection of methods and identification are discussed in the paper. LPT, MaI-1, Copan, Valio T 101, Penzym S, β-STAR, SNAP and ROSA tests for determining inhibitors in raw cows’ milk were evaluated. The objects of investigation - milk with selected concentrations of inhibitory substances (antibiotics, detergents, etc.) and “positive” samples (i. e. containing inhibitors) of raw milk. LPT, MaI-1 and Copan tests were sensitive to all β-lactams at EU Maximum Residue Limits (MRLs), the other tests (Valio T 101, Penzym S, β-STAR, SNAP and ROSA), to 2–4 of β-lactams investigated. All microbial tests were sensitive to the same detergents: TAAB-1, TAAB-2 and PESETTI ANTIBACT (0.2; 1.0 and 1.0 %, resp). The occurrence of inhibitors could not be evaluated by enzymatic and immuno/receptor tests in many cases because of abnormalities in colours or testing procedure. The results of investigating “positive” raw milk samples showed that there were no differences between MaI-I – Copan tests. Differences were found, though, between MaI-1 - Valio T 101, MaI-1 - Penzym S, MaI-1 - β-STAR and MaI-1 - ROSA tests. The comparison of the tests according to the method of use showed that the Copan test was simple to use and interpret, had a long shelf life and was sensitive to many groups of investigated inhibitors. β-STAR was the most rapid and easy to read the result from the immuno/receptor tests. Since the penicillins were determined to be the main group of inhibitors found in raw cows’ milk in Lithuania (86.2 % of the “positive” samples), the rapid tests for β-lactams can be successfully used for screening milk at the milk processing plants. A proposition concerning selection and validation of methods for identification of inhibitors realizing the Commission Decision of 91/180 EEC was made. |
