Validation of two commercial lateral flow devices for the detection of peanut proteins in cookies: interlaboratory study.

Results are reported for an interlaboratory validation study of 2 commercially available Iateral flow devices (dipstick tests) designed to detect peanut residues in food matrixes. The test samples used in this study were cookies containing peanuts at 7 different concentrations in the range of 0-30 mg peanuts/kg food matrix. The test samples with sufficient and proven homogeneity were prepared in our laboratory. The analyses of the samples (5 times per level by each laboratory) were performed by 18 laboratories worldwide which submitted a total of 1260 analytical results. One laboratory was found to be an outlier for one of the test kits. In general, both test kits performed well. However, some false-negative results were reported for all matrixes containing < 21 mg peanuts/kg cookie. It must be stressed that the test kits were challenged beyond their cut-off limits (> or = 5 mg/kg, depending on the food matrix). One test kit showed fewer false-negative results, but it led to some false-positive results for the blank materials. The sensitivity of the dipstick tests approaches that achieved with enzyme-linked immunosorbent assays.

Effect of roasting history and buffer composition on peanut protein extraction efficiency.

Peanut is a major allergenic food. Undeclared peanut (allergens) from mis-formulation or contamination during food processing pose a potential risk for sensitized individuals and must be avoided. Reliable detection and quantification methods for food allergens are necessary in order to ensure compliance with food labelling and to improve consumer protection. The extraction of proteins from allergenic foods and complex food products is an important step in any allergen detection method. In this study, the protein extraction efficiency of various buffers prepared in-house and some extraction buffers included in some commercial allergen enzyme-linked immunosorbent assay (ELISA) test kits for peanut determination in food products were tested. In addition, the effect of roasting history on the extractability of peanut protein was investigated by the biuret and the bicinchoninic acid (BCA) assays. Elevated roasting temperatures in food processing were found to have a major impact on protein extraction efficiency by reducing protein yields of oil and dry roasted peanuts by 50-75% and 75-80%, respectively, compared with the raw material. Extraction buffers operating in the higher pH range (pH 8-11) showed best yields.