The melamine issue ?a truly global case

THE widespread recall of melamine contaminated food products ?including infant formula in China, chocolates in Australia, pizza cheese in Taiwan, instant coffee in the U.S. and cheese crackers in Hungary ?is worrying consumers all over the world and impressively shows the globalization of food supply. Melamine being a contaminant you would not reasonably expect to find in milk, companies didn't have monitoring systems in place to test for it. Now that regulatory bodies have set maximum allowed levels of melamine in foodstuff, companies are starting to implement routine tests in their quality control programs. The European Food Safety Agency (EFSA) and the US Food and Drug Administration (FDA) have both concluded that the level of melamine in food products, other than baby food, should not exceed 2.5 mg/kg. Hong Kong and China have set its maximum concentration limit for melamine in baby food at 1.0 mg/kg, and 2.5 mg/kg for other foods. These limits are based on a so-called Tolerable Daily Intake (TDI). To illustrate, EFSA derived a TDI for melamine (and its analogues) of 0.5mg per kg of body weight per day. For a person weighing 70kg this would mean a daily intake of 35mg. At the 2.5 mg/kg limit such a person would have to consume more than 14kg of food a day or a near impossible 17.5 liters of milk to reach the daily tolerable intake of melamine. Testing accuracy and precision required The maximum limits set for melamine pose a challenge for dairy companies, especially from the analytical point of view. "To meet the 1 mg/kg limit for infant formulas the raw milk used for it must not exceed 100 parts per billion of melamine due to the tenfold concentration ratio during the drying process. Testing for melamine at such low levels requires an excellent method with high accuracy and precision for the matrices analyzed," says Dr. Michael Zheng, R&D director with Romer Labs Singapore, a global supplier of food safety diagnostics that provides a sensitive enzyme-linked immunosorbent assay (ELISA) test for melamine in dairy products. Direct competitive ELISA is probably the best alternative for dairy companies that do not have access to a sophisticated laboratory. The cost per test using a 96 well ELISA test kit is fairly economic and the investment in equipment such as a microwell reader, which is necessary to measure the optical density and subsequently quantify the melamine content, is also well under €10,000 depending on the model. "Dairy companies, especially those in remote areas, but also big multinational corporations and government institutions with many local labs opt for this method," says Limien Tan, sales director with Romer Labs Singapore. "The main advantage of the AgraQuant Melamine ELISA is that lab personnel can start working with the test on a routine basis in less than a day. Especially when your inventory is bursting at the seams waiting for product release, time is a crucial factor," explains Tan. Other analytical methods are based on high liquid performance chromatography (HPLC) either in combination with an UV-detector (HPLC-UV) or a mass spectrometer (LC-MS/MS). "HPLC-UV is a good option for industry labs because most of them do not have expensive MS/MS detectors available. The straightforward sample purification approach employing a MycoSep 224 column gives clean peaks for melamine in the chromatogram," says Dr. Georg Mitterer, technical manager with Romer Labs in Austria. "A drawback of this method is that you can't test for melamine-related compounds like cyanuric acid, ammeline, and ammelide due to their lack of UV absorbance. But those compounds are of high relevance for the food industry, being a result of melamine hydrolysis which can occur in various food processing steps," adds Dr. Mitterer, explaining that melamine develops its toxicity combined with cyanuric acid due to the formation of an insoluble melaminCrazy Explosive Boost 2017 PK Low