Quantification of allergenic bovine milk α(S1)-casein in baked goods using an intact ¹⁵N-labeled protein internal standard.
Intact bovine ¹⁵N-α(S1)-casein was used as an internal standard in a selected reaction monitoring (SRM) assay for milk protein in baked food samples containing fats, sugar, and gums. Effects on SRM results of sample matrix composition in two biscuit recipes containing nonfat dry milk (NFDM) were studied, including samples from a milk allergen ELISA proficiency trial. Following extraction of defatted samples with carbohydrate-degrading enzymes and acid precipitation of casein, the SRM assay exhibited an LOQ of <3 ppm NFDM with 60-80% recovery. NFDM levels measured by the SRM assay were 1.7-2.5 times greater than median levels determined by ELISA. Differences were observed in the α(S1)-casein interpeptide SRM ion abundance profile between recipes and after baking. ¹⁵N-α(S1)-Casein increases SRM analysis accuracy by correcting for extraction recovery but does not eliminate underestimation of allergen concentrations due to baking-related milk protein transformation (modifications).
Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , College Park, Maryland 20740, United States.
G Asher
GA
Newsome
Peter F
PF
Scholl
D000485:Allergens / Q000009:adverse effects / Q000032:analysis* / Q000737:chemistry; D000818:Animals; D001939:Bread / Q000009:adverse effects / Q000032:analysis; D002364:Caseins / Q000009:adverse effects / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D002417:Cattle; D003296:Cooking; D057140:Fast Foods / Q000009:adverse effects / Q000032:analysis*; D005513:Food Inspection / Q000379:methods*; D057141:Food, Preserved / Q000009:adverse effects / Q000032:analysis; D017127:Glycation End Products, Advanced / Q000009:adverse effects / Q000032:analysis / Q000737:chemistry; D006801:Humans; D007553:Isotope Labeling; D015416:Maillard Reaction; D008892:Milk / Q000009:adverse effects / Q000737:chemistry; D016269:Milk Hypersensitivity / Q000209:etiology / Q000517:prevention & control; D009587:Nitrogen Isotopes; D011994:Recombinant Proteins / Q000032:analysis / Q000737:chemistry; D012015:Reference Standards
D000485:Allergens; D002364:Caseins; D017127:Glycation End Products, Advanced; D009587:Nitrogen Isotopes; D011994:Recombinant Proteins