How do current protein detection methods identify and detect the addition of melamine and other substances in milk powder?
Currently, there are three main methods used for protein detection: the Kjeldahl method, the Dumas method, and infrared spectroscopy. Among these, the Kjeldahl method is the most widely used in the food industry. It measures the total nitrogen content in a sample and then estimates the protein content based on a standard conversion factor. This method has been the traditional standard for many years, but it's not without its flaws. The Kjeldahl method was first developed in 1883 and, despite being outdated by modern standards, it’s still commonly used due to the lack of a better alternative. The process is time-consuming, often taking several hours per sample, and involves the use of hazardous chemicals, including concentrated sulfuric acid, which must be heated to around 400°C. These conditions make the method both dangerous and inefficient. The Dumas method represents a more advanced approach. Instead of using chemical digestion, it burns the sample and measures the nitrogen released during combustion. While this method is faster and less chemically intensive, it also has limitations. It can't handle liquid samples or large volumes effectively, and the high-temperature combustion may introduce variability, making it difficult to achieve consistent results. As a result, users often limit the amount of sample they test to ensure accuracy. The third method, infrared spectroscopy, is a non-destructive, surface-based technique that provides quick results. However, it requires frequent calibration with a variety of reagents and is sensitive to other components in the sample, such as fats or carbohydrates. This sensitivity makes it less reliable for precise protein quantification, and it's often used only as a supplementary tool rather than a primary method. None of these methods directly measure actual protein molecules. Both the Kjeldahl and Dumas methods rely on measuring total nitrogen content and converting it to an estimated protein value. This approach has led to significant issues, especially when detecting adulterants like melamine. Since melamine contains nitrogen, it can artificially inflate the measured protein content, leading to false positive results. These methods cannot distinguish between true proteins and non-protein nitrogen sources, such as melamine, which is why they are vulnerable to food fraud. As a result, there is a growing need for more accurate and direct protein detection techniques that can identify real protein content and detect harmful additives like melamine. Until such methods become widely available, the current approaches remain in use, albeit with known limitations.Stainless Steel Plate,Hot 904L Stainless Steel Plate,Weathering Steel Plate,Stainless Steel Checkered Plate
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