Determination of allergenic egg proteins in food by protein-, mass spectrometry-, and DNA-based methods.
Egg allergy is one of the most common food allergies in both adults and children, and foods including eggs and their byproducts should be declared under food allergen labeling policies in industrial countries. Therefore, to develop and validate a sensitive and specific method to detect hidden egg allergens in foods, we compared immunochemical, DNA-based, and proteomic methods for detecting egg allergens in foods using egg allergen standards such as egg whole protein, egg white protein, egg yolk protein, ovomucoid, ovalbumin, ovotransferrin, lysozyme, and alpha-livetin. Protein-based immunochemical methods, including ELISA as an initial screening quantitative analysis and immunoblotting as a final confirmatory qualitative analysis, were very sensitive and specific in detecting potentially allergenic egg residues in processed foods in trace amounts. In contrast, the proteomics-based, matrix-assisted laser desorption/ionization time-of-flight MS and LC-tandem quadrupole time-of-flight MS methods were not able to detect some egg allergens, such as ovomucoid, because of its nondenaturing property under urea and trypsin. The DNA-based PCR method could not distinguish between egg and chicken meat because it is tissue-nonspecific. In further studies for the feasibility of these immunochemical methods on 100 real raw dietary samples, four food samples without listed egg ingredients produced a positive response by ELISA, but exhibited negative results by immunoblotting.
Lee
Ji-Yun
JY
Chung-Ang University, College of Pharmacy, Division of Pathophysiology and Pharmacology, 221 Huksuk-Dong, Dongjak-Ku, Seoul 156-756, South Korea.
Kim
Chang Jong
CJ
D000818:Animals; D002645:Chickens; D003207:Conalbumin / Q000737:chemistry; D004247:DNA / Q000032:analysis*; D004527:Egg Proteins / Q000737:chemistry; D004529:Egg White / Q000737:chemistry; D004530:Egg Yolk / Q000737:chemistry; D005504:Food Analysis / Q000379:methods*; D005512:Food Hypersensitivity / Q000175:diagnosis / Q000276:immunology*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D009113:Muramidase / Q000737:chemistry; D010047:Ovalbumin / Q000737:chemistry; D010059:Ovomucin / Q000737:chemistry; D010063:Ovum / Q000378:metabolism*; D011506:Proteins / Q000032:analysis*; D040901:Proteomics / Q000379:methods
D004527:Egg Proteins; D011506:Proteins; D003207:Conalbumin; D010059:Ovomucin; D010047:Ovalbumin; D004247:DNA; C039690:livetin; D009113:Muramidase