Food Science Institute, Dept. of Animal Sciences and Industry, Kansas State Univ., Manhattan, KS 66506, USA.
J Food Sci. 2010 Aug 1;75(6):T118-22. doi: 10.1111/j.1750-3841.2010.01706.x.
The amount of irradiated beef in the U.S. market is growing, and a reliable, rapid method is needed to detect irradiated beef and quantify the irradiation dose. The official analytical method (BS EN 1785 2003) that has been adopted by the European Union is time consuming. The objective of this study was to develop a rapid method for the analysis of 2-dodecylcyclobutanone (2-DCB) in irradiated beef. A 5 g sample of commercially irradiated ground beef patty (90/10) was extracted with n-hexane using a Soxhlet apparatus or with acetonitrile via direct solvent extraction. The Soxhlet hexane extract was evaporated to dryness, and the sample was dissolved in a mixture of ethyl acetate and acetonitrile (1:1). The defatted extract was purified with a 1 g silica cartridge. Another 5 g aliquot of the same patty was mixed with 50 mL acetonitrile and either blended for 1 min with a hand blender or crushed for 10 min with a glass rod. The extraction procedure was repeated 3 times, and the acetonitrile was collected and evaporated to dryness. Eluants from both methods were concentrated under nitrogen and injected into a gas chromatography-mass spectrometry. The 2-DCB concentration in the commercial samples was 0.031 +/- 0.0026 ppm (n = 5) for the Soxhlet method and 0.031 +/- 0.0025 ppm (n = 10) for direct solvent extraction. Recovery of 2-DCB from spiked beef samples in the direct solvent extraction method was 93.2 +/- 9.0% (n = 7). This study showed that the direct solvent extraction method is simple and as efficient and reproducible as the Soxhlet method.
美国市场辐照牛肉的数量在不断增加，因此需要一种可靠、快速的方法来检测辐照牛肉并定量辐照剂量。欧盟采用的官方分析方法（BS EN 1785 2003）耗时较长。本研究旨在开发一种快速分析辐照牛肉中 2-十二烷基环丁酮（2-DCB）的方法。采用索氏提取或直接溶剂提取法，用正己烷从商业辐照碎牛肉饼（90/10）中提取 5g 样品。索氏正己烷提取物蒸发至干，将样品溶解于乙酸乙酯和乙腈（1:1）的混合物中。用 1g 硅胶柱对脱脂提取物进行纯化。对同一块肉饼的另 5g 等分试样，与 50ml 乙腈混合，用手动搅拌器混合 1 分钟或用玻璃棒粉碎 10 分钟。重复提取 3 次，收集乙腈并蒸发至干。两种方法的洗脱液在氮气下浓缩，注入气相色谱-质谱联用仪。索氏法和直接溶剂提取法中商业样品的 2-DCB 浓度分别为 0.031±0.0026ppm（n=5）和 0.031±0.0025ppm（n=10）。直接溶剂提取法从添加牛肉样品中回收 2-DCB 的回收率为 93.2±9.0%（n=7）。本研究表明，直接溶剂提取法简单、高效、重现性好，与索氏法相当。
