Fat and moisture content determination with unilateral NMR

Unilateral (one-sided) NMR, with easy sample access and rapid “through-package” measurement, is a promising new technology in food science. Here we investigated the applicability of two methods for fat and moisture content determination by unilateral NMR. One is a post-measurement decomposition of a Carr–Purcell–Meiboom–Gill (CPMG) signal using a classical least-squares (CLS) multivariate analysis. The other is based on a diffusion-weighted CPMG experiment, where the components are discriminated at the time of measurement through the diffusivity difference between fat and moisture. The experiments were carried out on model samples of cod liver oil emulsion in water and on commercial ground beef. The CLS analysis exhibits a good predictive performance provided the fat and moisture components conserve their characteristic relaxation times in different samples. The diffusion-weighted CPMG, although more complex experimentally, is free of this restriction. The methods will be of interest for online analysis of food materials and supplement laborious standard extraction methods.