RAPID MOISTURE AND FAT DETERMINATION BY PULSED NMR FOR MONITORING DRYING AND COATING PROCESSES OF EXTRUDATES

After extrusion cooking, extrudates must be dried and are often coated by spraying with fatty materials before cooling and packaging. As a m eans to control the drying and coating processes of pet foods, a rapid NMR method was developed to determine water and fat contents over a l arge temperature range without weighing, heating or measuring the temp erature of the samples. Weighing was avoided by normalizing all NMR in tensities by the solid echo maximum of each sample. Formulae using est imates of the transverse relaxation time and the concentration of liqu id fat protons were used to determine total fat and moisture contents without measuring the temperature of the samples. Fat content estimati on had a standard deviation better than 0.2% over a large solid fat in dex range above 20 degrees C. Water content was determined with a stan dard deviation of about 0.2% at all temperatures studied.