Commercial Milk Enzyme‐Linked Immunosorbent Assay (ELISA) Kit Reactivities to Purified Milk Proteins and Milk‐Derived Ingredients

Abstract

Numerous commercial enzyme-linked immunosorbent assay (ELISA) kits exist to quantitatively detect bovine milk residues in foods. Milk contains many proteins that can serve as ELISA targets including caseins (α-, β-, or κ-casein) and whey proteins (α-lactalbumin or β-lactoglobulin). Nine commercially-available milk ELISA kits were selected to compare the specificity and sensitivity with 5 purified milk proteins and 3 milk-derived ingredients. All of the milk kits were capable of quantifying nonfat dry milk (NFDM), but did not necessarily detect all individual protein fractions. While milk-derived ingredients were detected by the kits, their quantitation may be inaccurate due to the use of different calibrators, reference materials, and antibodies in kit development. The establishment of a standard reference material for the calibration of milk ELISA kits is increasingly important. The appropriate selection and understanding of milk ELISA kits for food analysis is critical to accurate quantification of milk residues and informed risk management decisions.

The Effect of Different Methods of Fermentation on the Detection of Milk Protein Residues in Retail Cheese by Enzyme‐Linked Immunosorbent Assay (ELISA)

“…Results obtained with the r‐Biopharm RIDASCREEN® Fast Casein Kit and the Neogen Veratox® Total Milk Kit (Table ) were comparable in trend. This is not surprising since both of these kits are primarily sensitive to κ‐casein (Ivens and others ).…”

“…To compare the results for the 18 cheeses among the 4 ELISA kits, the results were converted, where necessary to mg/kg casein (Ivens and others ). Values for detected mg/kg casein were plotted on a log scale graph and organized by cheese variety (Mozzarella, Swiss, Blue, Limburger, and Brie; Figure ).…”

“…Kit information regarding the levels of detection and quantitation (LOD and LOQ, respectively), composition of the manufacturer‐provided standard solutions, and kit reporting units are displayed in Table . The specificities of the kits for individual milk proteins is detailed in previous work (Ivens and others ). Kits were selected for inclusion on the basis of reliable and consistent performance in preliminary studies.…”

“…Optical density readings for unknown samples were fit to the curve and results were interpolated. Where appropriate for comparisons, ELISA Kit results were converted to relevant units according to Ivens and others ().…”

Potential allergenicity assessment after bovine apo‐α‐lactalbumin binding to calcium ion

“…CMP are also the most common food allergens (Perezabad et al., 2017), and the incidence of cow's milk allergy (CMA) ranges from 2% to 7.5% in developed countries (D'Apolito, Campanozzi, Giardino, & Pettoello‐Mantovani, 2017; Fiocchi et al., 2010). CMP mainly include caseins (80%) and whey proteins (20%), and the major allergens in whey proteins are β‐lactoglobulin and α‐LA (Ivens, Baumert, & Taylor, 2016). α‐LA accounts for 25% of whey proteins (Høst & Halken, 2014).…”