Regulatory Affairs Department, Alltech Ireland , Dunboyne , Ireland.
Alltech SARL , Vire , France.
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2019 Oct;36(10):1467-1474. doi: 10.1080/19440049.2019.1644457. Epub 2019 Aug 8.
Urea is a non-protein nitrogen compound, authorised in the EU as a nutritional source of nitrogen in animal feed intended for ruminants with a functional rumen. The Rapid Alert System for Food and Feed (RASFF) is the EU online platform through which food and feed safety risks are reported. During 2017, several rapid alerts were raised in the EU by individual member states regarding the presence of unlabelled urea in feed-grade yeast. The presence of urea in animal feed is analysed with a spectro-colorimetric method, which is the EU official control method. Other urea analytical methods include enzymatic and LC-MS methods, which are also investigated in this study. The main objectives of this study were to analyse yeast feed-grade and food-grade products with independent laboratories using the EU official control method, as well as enzymatic and LC-MS methods. Comparison of results from the spectro-colorimetric, enzymatic and LC-MS methods for reliability, consistency and accuracy determined the most reliable method for the quantification of urea in animal feed. Yeast food and feed samples were tested using four independent laboratories. Results demonstrated a lack of consistency both within the same laboratory and between separate laboratories for urea quantification using the EU official control method. Urea quantification results for the AOAC 941.04 enzymatic method were found to be much higher than anticipated. The LC-MS method yielded the most consistent and reliable results. In conclusion, urea quantification by LC-MS analysis has the potential to be a viable method for urea analysis of yeast samples.
尿素是一种非蛋白氮化合物，在欧盟被批准作为有功能性瘤胃的反刍动物饲料的氮源。食品和饲料快速预警系统（RASFF）是欧盟在线平台，通过该平台报告食品安全风险。在 2017 年，几个成员国在欧盟提出了几项快速警报，涉及饲料级酵母中未标记尿素的存在。动物饲料中尿素的存在采用分光比色法进行分析，这是欧盟的官方检测方法。其他尿素分析方法包括酶法和 LC-MS 法，本研究也对其进行了研究。本研究的主要目的是使用欧盟官方控制方法以及酶法和 LC-MS 法，由独立实验室分析饲料级和食品级酵母产品。为了确定用于动物饲料中尿素定量的最可靠方法，对分光比色法、酶法和 LC-MS 法的可靠性、一致性和准确性进行了比较。使用四个独立实验室对酵母食品和饲料样品进行了测试。结果表明，使用欧盟官方控制方法对尿素进行定量时，同一实验室和不同实验室之间的结果都缺乏一致性。AOAC 941.04 酶法的尿素定量结果比预期的高很多。LC-MS 方法的结果最一致和可靠。总之，通过 LC-MS 分析进行尿素定量分析有可能成为酵母样品尿素分析的一种可行方法。
