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Phân tích chất béo và độ ẩm bằng cách làm khô lò vi sóng và cộng hưởng từ hạt nhân (NMR) là một phương pháp trực tiếp mang lại kết quả chính xác trong vài phút mà không có dung môi hay hiệu chỉnh thường xuyên theo yêu cầu của phương pháp gián tiếp như hồng ngoại gần (NIR), hoặc biến đổi Fourier hồng ngoại (FTIR). | Chapter 8 The Rapid Determination of Fat and Moisture in Foods by Microwave Drying and NMR Analysis Bobbie McManus and Michelle Horn CEM Corporation Matthews NC 28106-0200 Abstract Fat and moisture analysis by microwave drying and nuclear magnetic resonance NMR is a direct method that yields accurate results in minutes without solvents or the frequent calibration required by indirect methods such as near infrared NIR or Fourier transform infrared FTIR . In the past NMR was unreliable for determining fat content in foods because the signal from moisture present in the sample interfered with the fat reading. There is now a peer-verified microwave drying and NMR analysis AOAC PVM 1 2003 for quantification of the percentage of moisture and fat in meat products. The procedure involves determining the moisture value of meat samples by microwave drying and using the dried sample to determine the fat value by NMR analysis. Five meat products were analyzed using a CEM SMART SystemTM Moisture and the SMART TracTM System Fat . The samples representing a range of products that meat processors commonly analyze in daily plant operations included the following i fresh ground beef high fat ii deboned chicken with skins iii fresh pork low fat iv all beef hot dogs and v NIST standard reference material samples. The results were compared with moisture and fat values derived from AOAC-approved methods 950.46 Forced Air Oven Drying and 960.39 Soxhlet Ether Extraction. The chapter also discusses the analysis of dairy samples by microwave moisture analysis and NMR fat analysis. These samples include cream ice cream and milk with various levels of fat. Results are compared with the Mojonnier and Gerber techniques. Introduction Traditionally foods have been tested for fat using various wet chemistry methods that are both time consuming and require more than a passing knowledge of chemistry 1 . With the introduction of near infrared NIR and Fourier transform infrared FTIR instruments .
