Immunodetection of lactosylated proteins as a useful tool to determine heat treatment in milk samples

This paper reports the optimisation of a competitive immunoassay (ELISA) to detect lactosylated proteins in milk samples. The assay employs monoclonal antibodies for lactosylated proteins produced in our laboratory and requir es no pre-treatment of the samples other than a dilution step Monoclonal an tibodies were fully characterised in terms of selectivity and cross-reactiv ity with structurally related molecules and used in a competitive assay for mat with lactosylated standard proteins (lactosylated ovalbumin). The detec tion limit for lactosylated ovalbumin was 0.015 mug ml(-1) and the working range was from 0.010 to 40 mug ml(-1). The data obtained indicate that the ELISA developed is applicable to diluted milk samples and is able to distin guish between milk samples that have undergone different heat treatments (U HT and pasteurised milk).