IMMUNOCHEMICAL DETECTION OF OVALBUMIN IN DAIRY-BASED FOODS

Commercially available antibodies were used for the detection and quan titation of ovalbumin in ice cream and cheese. Electrophoretic separat ion of protein components, followed by blotting and immunochemical rec ognition of ovalbumin allowed the detection of the addition of greater than or equal to 50 g kg(-1) egg white to processed cheese and allowe d detection of egg in ice cream. For quantitative purposes a competiti ve ELISA method was set up. Calibration curves for ovalbumin in variou s products were obtained. A marked matrix effect was evident in ice cr eam, cheese and yoghurt. Different types of cheese gave nearly identic al matrix effects. Analytical application of the method should therefo re be possible, at least within a given class of products. A study on the influence of thermal treatments on the ELISA response showed that melting of cheese at various temperatures modifies only slightly the E LISA response for ovalbumin.