Determination of total fat content (TFC) becomes increasingly important in food industry because fat content is a one of main indicators of food quality. The traditional methods of fat determination have relatively low accuracy and reproducibility because they are based on solvent extraction, which is time consuming, uses harmful reagents and solvents and the accuracy of the results depends on effectiveness of solvent extractability and personnel knowledge and experience. TD-NMR is a fast and accurate alternative technique for determination the total fat content.
TD-NMR is nondestructive, easily adaptable to on-line measurement, requires no weighting, does not use chemicals. TD-NMR can be used to analyze most food products along the production process from the raw material until the finished product. Pulse sequence "Spin Echo" is used in this application. This specific proton signal is related to the total amount of nuclei which are proportional only to the fats (lipids) of the sample. The percentage of total fat is calculated as the ratio between the spin echo amplitude and the free induction decay amplitude which includes signals from all components of the sample. Before NMR measurement the sample is conditioned at 80 °C inside test tube. Duration of total fat determination is not more than 17 min including sample preparation.
TD-NMR analyzer Spin Track from Resonance System with 10 mm or 18 mm test tube is ideal instrument for TFC measurements because of fine technical characteristics which make measurements very reproducible and accurate. Analyzer fulfills the requirement of AOAC Official Method 2008.06 "Moisture and Fat in Meats. Microwave and Nuclear Magnetic Resonance Analysis" revised in 2013. The intrument is submitted with calibration samples and tempering devices. Spin Track maintains automatic start of the measurement.