Abstract
Bovine β‐lactoglobulin (βLG) has been described by several authors as the main allergen present in cow's milk. It can induce allergic reactions even at the low concentration existing in hypoallergenic formulas based on hydrolyzed cow's milk proteins (generally lower than μM). In this paper, the usefulness of a capillary electrophoresis method with on‐capillary derivatization and laser‐induced fluorescence detection for the analysis of trace amounts of βLG in a commercial hypoallergenic formula has been demonstrated. To confirm the identity of the peak of βLG based on migration time, an immunorecognition step employing an anti‐βLG antibody was performed. βLG was quantitated in the whey and casein fractions of the hypoallergenic formula. The concentration of βLG in the whey fraction of the formula was about 3 orders of magnitude lower than the average value present in cow's milk. In the casein fraction of the formula, the concentration of βLG was about 1 order of magnitude lower than in the whey fraction. The method developed was also used for the quality control of three cereal‐based infant foods formulated without milk to test the presence or absence of βLG as an indicator of milk contamination during the fabrication process. βLG in a concentration of 10^–7^ M or higher was not observed in any of the cereal‐based infant formulas analyzed.