title: Quantitative evaluation of pork adulteration in raw ground beef by radial immunodiffusion and enzyme-linked immunosorbent assay.
abstract: Quantitative estimates are important to establish whether pork adulteration in ground beef is accidental or intentional. A standard agar gel radial immunodiffusion (RID) test using forensic-grade antiserum to porcine albumin and an enzyme-linked immunosorbent assay (ELISA) using forensic-grade anti-porcine glycoprotein immunoglobulin were used to determine from 1 to 75% raw pork in raw ground beef. The RID test, which incorporated 1.5% anti-pork serum in 1% immunodiffusion agar, formed precipitin rings with pork albumin in agar wells. A linear standard curve was obtained by plotting the diffusion area against standard pork concentrations ranging from 0 to 80%. For the ELISA the endpoint optical density increased linearly versus log % pork between 0.0625% and 2% pork. In spiked samples, the RID test had a detection limit of 3 to 5%, a coefficient of variation (CV) of 22%, and a recovery of 105%. The ELISA had a detection limit of 1%, a CV of 18%, and a recovery of 114%. The mean recovery from the spiked samples by the ELISA and RID test was not significantly different (P > 0.05) from the known sample amounts. Quantitation by RID of 28 ground beef samples (27 of which were DTEK ELISA-positive for pork adulteration) revealed a wide range of pork content, with values as high as 48%.
authors.affiliation: U.S. Department of Agriculture, Food Safety and Inspection Service, Western Laboratory, Alameda, California 94501-3874, USA. wlab@worldnet.att.net
authors.forename: D R
authors.initials: DR
authors.lastname: Martin
authors.forename: J
authors.initials: J
authors.lastname: Chan
authors.forename: J Y
authors.initials: JY
authors.lastname: Chiu
mesh_terms: D000818:Animals; D002417:Cattle; D004797:Enzyme-Linked Immunosorbent Assay; D005506:Food Contamination; D005513:Food Inspection / Q000379:methods* / Q000592:standards; D005779:Immunodiffusion; D008461:Meat Products / Q000032:analysis*; D013552:Swine