Low-field NMR relaxation and NMR-imaging as tools in differentiation between potato sample and determination of dry matter content in potatoes

Abstract

Correlations between dry matter content and parameters determined by low-field nuclear magnetic resonance (NMR) relaxation and T 1 weighted magnetic resonance imaging (MR-imaging) were investigated in four raw potato varieties using partial least-squares regression. The low-field NMR relaxation parameters T 1( r=−0.85) and full Carr–Purcell–Meiboom–Gill (CPMG) relaxation curves ( r=0.95) were correlated with the dry matter content of the potatoes. Furthermore, the amplitudes M 21 and M 22 of the two characteristic transverse relaxation ( T 2) time constants T 21 and T 22 obtained upon bi-exponential analysis of CPMG relaxation curves, were also highly correlated with the dry matter content ( r=−0.66 and 0.78, respectively). MR-images showed very large visual differences between tissues, varieties and maturity. However, the applied image analysis features based on the histogram analysis were not correlated with dry matter content in whole potatoes in the present study. Thus, MR-imaging did not complement the correlations between NMR data and dry matter content. This means that the way the spatial distribution of water in the material was determined did not cover the full information about dry matter content. Therefore, the image analysis of MR-images requires more attention in the future.