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Trong quá khứ, NMR là không đáng tin cậy để xác định hàm lượng chất béo trong thực phẩm bởi vì các tín hiệu từ nay độ ẩm trong mẫu can thiệp với đọc lượng chất béo. Hiện nay có một mạng ngang hàng xác nhận, sấy lò vi sóng và phân tích NMR (AOAC PVM 1:2003) để định lượng tỷ lệ phần trăm của độ ẩm và chất béo trong các sản phẩm thịt. | Chapter 9 Simple Methods for Measuring Total Oil Content by Benchtop NMR P.H. Krygsman and A.E. Barrett Bruker Optics Ltd. Minispec Division 555 Steeles Ave. East Milton Ontario L9T 1Y6 Canada Abstract Low-resolution time domain nuclear magnetic resonance TD-NMR is an internationally recognized and commercially important analytical tool for measuring the oil content in oilseeds and oilseed residues. It is commonly employed as a simultaneous determination of oil and moisture content as in ISO 10565 or AOCS Ak 495. Because the method is very fast compared with oven drying to determine moisture and extraction to determine oil rapid and more frequent testing is possible and dry-weight oil is easily reported. The NMR method is widely used in European countries especially France and Germany for oil in sunflower rape and soybean. A related method used in Spain is oil in olives for assigning commercial value. In North America and South America official oil content in canola and sunflower is determined by the NMR method. All other oilseeds are amenable to the method including soy flax corn cotton and peanut. A large part of the reason for the success of the method is the simplicity of calibration. In cases in which rapid and accurate screening of oil content is the primary concern simple calibration maintenance is desired. Calibration for oil can involve as few as two or three reference oilseed samples. Often 5-20 calibration samples are used to satisfy statistical variation in the natural product. Repeatability of measurement is usually limited by subsampling error. If the same sample is measured repeatedly the SD is typically 0.02. Agreement between duplicate samples taken from the same lot depends on the oilseed and size of sample used. It was found to be 0.1-0.2 for soybean measured in 22-g samples. TD-NMR measures oil by detecting the hydrogen in the liquid phase of the sample. The NMR signal for oil is well isolated and normally free of interference from other .
