Variability in determination of the single kernel moisture content of grain by means of TD-NMR spectroscopy

Abstract

Detailed information on the moisture distribution of grains is important to predict its storability, because there can be a significant variance in the moisture content among individual grain kernels. Hence, it is important to determine the single kernel moisture content. For it, the time domain nuclear magnetic resonance (TD-NMR) spectroscopy was applied and adopted for the non-destructive measurement at different types of grain with the focus on wheat. The TD-NMR is widely used in food industry to determine the moisture content precisely. The influence of the single kernel position in the measuring cell was examined more closely. As could be demonstrated, the particle moisture varied significantly depending on the angular position in the TD-NMR spectroscope. When the kernel was turned by 90°, the moisture deviated by up to 0.9% wet basis, and this deviation increased as the grain water content increased. In addition, the experiments showed that the dry mass of the kernel has an impact on the received moisture content. Hence, the kernel should always have the same position in the NMR-spectroscope. Also the calibration should be carried out in this position and a wide range of kernel weight should be selected.