Matrix Effects on the Detection of Milk and Peanut Residues by Enzyme-Linked Immunosorbent Assays (ELISA)

Food matrices are complex systems of lipids, carbohydrates, and proteins in which interactions between matrix components and allergenic proteins are known to have negative effects on the recovery of allergens when analyzed by ELISA. The purpose of this study was to first evaluate the recovery of milk and peanut residues from multiple food matrices and mixes and to secondly evaluate the use of a modified extraction protocol, sequential extractions, on the recovery of milk and peanut allergens. Pastry dough matrices and pastry dough mixes incurred with milk were prepared at varying concentrations of flour and evaluated for recovery of NFDM. Secondly, a series of samples were prepared with increasing flour concentrations (wheat, corn, rice, soy flour) while maintaining a constant allergen (milk or peanut) concentration. Evaluation of sequential extractions was done on pastry matrices (wheat, corn, or rice flour) incurred with milk or peanut. Two matrix types, raw dough and baked matrices were analyzed for recovery. Recovery of NFDM was reduced in wet pastry dough matrices in comparison to dry pastry dough mixes, indicating that the formation of a food matrix influences the detection of allergens. In concentration mixes, upon the addition of each flour type, the recovery of milk residues decreased as the concentration of flour increased whereas the recovery of peanut residues was not affected by the increasing concentrations of flour. The implementation of sequential extractions yielded additional soluble protein from all matrices analyzed. Interestingly, ELISA detectable protein was only extracted from raw dough matrices. No detectable allergenic protein was extracted from baked pastry matrices. The formation of a food matrix reduces the detection of milk allergens and reduced recoveries of milk allergens were observed with both glutinous and non-glutinous flour mixes. Peanut residues are less affected in sample mixes of different flour types. The use of a modified extraction procedure improved the recovery of soluble protein (all matrices) and allergenic protein (in raw matrices only). Advisors: Stephen L. Taylor and Joseph L. Baumer