Determination of sorbitol crystal content and crystallization rate using TD-NMR

• TD-NMR can accurately determine sorbitol crystal content in low moisture systems.
• An exponential model equation can be used to predict sorbitol crystal content.
• Crystallization rate increased as temperature decreased due to higher supersaturation.
• Low molecular mobility did not reduce crystallization rate at low temperature.

Sorbitol crystallization in low moisture systems is difficult to measure using traditional methods such as differential scanning calorimetry, microscopy, and x-ray diffraction. This study developed a novel method for sorbitol crystal content determination using a time domain nuclear magnetic resonance (TD-NMR) method adapted from that commonly used to measure solid fat content and recently proven to measure sucrose crystal content (Porter and Hartel, 2013). TD-NMR was proven to accurately measure sorbitol crystal content (p < .5) and was then used to determine crystallization rate at a variety of moisture contents (0.8%, 1.7%, 4.2%, and 6.7%) and crystallization temperatures (10 °C, 25 °C, and 40 °C). Data for crystal content as a function of time was fit to a growth model, which was further used to derive crystallization rate and phase diagrams with contour plots. Importantly, this study marks the first time γ-sorbitol crystallization rate has been quantified in literature.