Development and evaluation of two ELISA formats for the detection of β-lactoglobulin in model processed and commercial foods

Milk proteins have many functional properties, making them valuable food ingredients. However, they are a frequent cause of food allergy, especially in children. The aim of the present work was to develop and evaluate two immunoassays (indirect competitive and double antibody sandwich formats) for the detection of undeclared milk proteins in foods. Antisera raised to β-lactoglobulin was used in the competitive assay and antibodies isolated by immunoadsorption in the sandwich ELISA. Results obtained indicated that the sandwich format could detect lower percentages of powdered milk added to processed model foods than the competitive format. Likewise, the sandwich assay could discriminate better than the competitive assay between commercial foods with declared or non-milk ingredients. The antibody population used to recognize the target protein as well as the particularities of each ELISA format greatly influence the determination of immunoreactive β-lactoglobulin present in processed food.