Martin D R, Chan J, Chiu J Y
U.S. Department of Agriculture, Food Safety and Inspection Service, Western Laboratory, Alameda, California 94501-3874, USA.
J Food Prot. 1998 Dec;61(12):1686-90. doi: 10.4315/0362-028x-61.12.1686.
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%.
定量评估对于确定牛肉末中猪肉掺假是偶然还是故意的很重要。使用法医级猪白蛋白抗血清的标准琼脂凝胶放射免疫扩散（RID）试验和使用法医级抗猪糖蛋白免疫球蛋白的酶联免疫吸附测定（ELISA）来测定生牛肉末中1%至75%的生猪肉。RID试验在1%免疫扩散琼脂中加入1.5%抗猪血清，在琼脂孔中与猪白蛋白形成沉淀环。通过绘制扩散面积与0%至80%标准猪肉浓度的关系图获得线性标准曲线。对于ELISA，在0.0625%至2%猪肉之间，终点光密度相对于猪肉对数百分比呈线性增加。在加标样品中，RID试验的检测限为3%至5%，变异系数（CV）为22%，回收率为105%。ELISA的检测限为1%，CV为18%，回收率为114%。ELISA和RID试验对加标样品的平均回收率与已知样品量相比无显著差异（P>0.05）。通过RID对28个牛肉末样品（其中27个DTEK ELISA检测猪肉掺假呈阳性）进行定量分析，结果显示猪肉含量范围很广，高达48%。
