Determination of water droplet size in margarines and low‐calorie spreads by nuclear magnetic resonance self‐diffusion

Abstract

AbstractThe nuclear magnetic resonance self‐diffusion technique can be used to determine the size of emulsion droplets. In this communication, the method is discussed and applied to some margarines and low‐calorie spreads, ranging in fat content from 40 to 80%. The data show that the droplet size distribution is fairly polydisperse, at least for the solid margarines studied. A liquid margarine, containing 80% fat and studied by optical microscopy, showed that a lognormal size distribution function is a reasonable description of its size polydispersity. Therefore, this distribution function was used in the present work, and the parameters of the log‐normal function were determined by a least‐square fit directly on the experimental raw data for all the systems studied. The uncertainties of the obtained parameters are judged by means of a Monte Carlo technique. The uncertainty is around ±15% (or better). Finally, we discuss the possibility of the presence of nonspherical droplets and how the presence of such droplets would actually affect the measurements.