Global Proteomic Screening of Protein Allergens and Advanced Glycation Endproducts in Thermally Processed Peanuts

• Published in: Journal of agricultural and food chemistry Vol. 61; no. 24; pp. 5638 - 5648
• Main Authors: Hebling, Christine M, McFarland, Melinda A, Callahan, John H, Ross, Mark M
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 19.06.2013
• Subjects: allergens; Allergens - adverse effects; Allergens - analysis; Allergens - chemistry; Antigens, Plant - adverse effects; Antigens, Plant - analysis; Antigens, Plant - chemistry; Arachis - adverse effects; Arachis - chemistry; Arachis hypogaea; food allergies; Food Inspection - methods; food labeling; Food, Preserved - adverse effects; Food, Preserved - analysis; glycation; Glycation End Products, Advanced - adverse effects; Glycation End Products, Advanced - analysis; Glycation End Products, Advanced - chemistry; Hot Temperature - adverse effects; Humans; lysine; Maillard Reaction; molecular weight; Nuts - adverse effects; Nuts - chemistry; Peanut Hypersensitivity - etiology; Peanut Hypersensitivity - prevention & control; peanut protein; peanuts; Peptide Fragments - adverse effects; Peptide Fragments - analysis; Peptide Fragments - chemistry; peptides; Plant Proteins - adverse effects; Plant Proteins - analysis; Plant Proteins - chemistry; polyacrylamide gel electrophoresis; processed foods; Proteome - adverse effects; Proteome - analysis; Proteome - chemistry; proteomics; Proteomics - methods; roasting; screening; Western blotting; Maillard reaction; Ara h; mass spectrometry; roasted peanuts; peanut allergens; AGE
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf303554t

Peanuts (Arachis hypogaea) are the cause of one of the most prevalent food allergies worldwide. Thermal processing (e.g., roasting) of peanuts and peanut-containing foods results in complex chemical reactions that alter structural conformations of peanut proteins, preventing accurate detection of allergens by most immunochemical and targeted screening methodologies. To improve food allergen detection and support more accurate food labeling, traditional methods for peanut protein extraction were modified to include protein denaturants and solubilization agents. Qualitative characterization by SDS-PAGE and Western blot analyses of raw and variably roasted peanut extracts confirmed improvements in total protein recovery and provided evidence for the incorporation of Ara h 1, Ara h 3, and, to a lesser extent, Ara h 2 into high molecular weight protein complexes upon roasting. Relative quantification of allergens in peanut lysates was accomplished by label-free spectral feature (MS1) LC-MS/MS methodologies, by which peanut allergen peptides exhibiting a differential MS response in raw versus roasted peanuts were considered to be candidate targets of thermal modification. Identification of lysine-modified Maillard advanced glycation endproducts (AGE) by LC-MS/MS confirmed the formation of (carboxymethyl)lysine (CML), (carboxyethyl)lysine (CEL), and pyrraline (Pyr) protein modifications on Ara h 1 and Ara h 3 tryptic peptides in roasted peanut varieties. These results suggest that complex processed food matrices require initial analysis by an untargeted LC-MS/MS approach to determine optimum analytes for subsequent targeted allergen analyses.