Rapid method for determining fat content in meat by using continuous wave nuclear magnetic resonance (CW-NMR) technique

Development of rapid methods is often needed for the in-line process contro l of the proximate composition (e.g. fat or moisture content) of meal in th e meat processing plants. This paper reports on the continuous wave nuclear magnetic resonance (CW-NMR) technique applied for determining fat content in fresh meat. The interfering moisture content in meat was removed by micr owave drying and the dried residue was transferred quantitatively into the NMR-tubes. The total analysis time was about 35 min. Experiments were perfo rmed with pork (with a fat content from 1.7% to 21%), beef (with a fat cont ent from 1.0% to 16.1%), lard (rendered pork fat) and tallow (rendered beef fat) samples and with their combinations: lard-tallow, lard-lean pork, tal low-lean beef and lard-tallow-lean beef-lean pork. The regression (prediction) equations (NMR-signal vs. fat content determine d with the Soxhlet reference method) of pork and beef did not differ signif icantly. However, there was a noticeable difference between the regression lines of pure lard and pure tallow. Moreover, the latter ones differed from the regression equations of pork, beef and of the various meat-fat combina tions. The variability of the fatty acid composition of the fat also seems to influence the stability of the calibration curves, because the sensitivi ty of the CW-NMR signal to the fatty acid composition interferes with the q uantitative determination offal content in meat.