The determination of solid fat content (SFC) is an important analytical procedure in the food industry. The most common way to determine SFC is by low-resolution pulsed NMR (p-NMR). Although this technique is very sensitive and easy to use, it has the disadvantage that it cannot be used for on-line measurements. The present work compares new technologies to determine SFC on-line. On-line ultrasonic spectroscopy and NMR-MOUSE (NMR mobile universal surface explorer) techniques were compared with off-line p-NMR measurements and there was a good correlation between the values obtained. Ultrasonic measurements accurately described the SFC variation, whereas NMR-MOUSE determinations need to be improved to some extent owing to a strong temperature and motion dependence. These two techniques can be used as on-line methodologies to determine SFC during the crystallization of fats.