Quantitative Western blot assay for the detection of chicken serum albumin (Gal d 5).

Egg is one of the Big-Nine allergenic foods in the U.S., and accurate detection of its allergenic proteins is critical for food safety. Chicken serum albumin (CSA, Gal d 5), an allergen found in egg yolk, chicken meat, and avian-derived materials, remains under-detected in food products. This study aimed to characterize CSA and develop a quantitative Western blot (qWB) assay for the detection of CSA. After characterization, (1) high temperature (>69.61 °C) decreased CSA extractability, (2) in vitro allergenicity was detected by human plasma, and (3) CSA was verified in egg white. A monoclonal antibody 3H4E9 was characterized as specific to poultry serum albumin. The optimized qWB assay exhibited good selectivity (specific to poultry species), working range (0.3-20 ppm), and sensitivity (ppm level). This assay enables sensitive and reliable CSA detection on food contact surfaces, facilitating risk assessment of undeclared egg yolk residues and improving food safety management practices.