Simultaneous determination of fat and water content in caramel using time domain NMR

In the production process of caramel mass it would be desirable to determine the contents of water and fat simultaneously in one single analytical step.In classic time domain NMR methods, the differentiation of water and fat is not sufficiently good as the differences in relaxation times of oils and fats are relatively small. As only signal amplitudes at given times are evaluated in classic time domain NMR, the contrast between the compounds is too small to allow a quantification. Therefore, samples are always pre-dried, allowing the determination of the fat content by time domain NMR.Therefore a new TD-NMR method using a combined relaxation analysis was used, where the magnetisation at a certain time is determined by both T1 and T2. This combination leads to an increase of contrast and therefore opens up the possibility of quantification of water and fat by time domain NMR simultaneously. For data-processing, a chemometric method was employed to establish correlation with the results of the reference methods for fat and water content.