Low field nuclear magnetic resonance (NMR) is used as a non-invasive method for detecting spoiled tomato paste. It is shown that the 1H T1 and T2 relaxation times change as tomato paste spoils due to changes in viscosity and/or changes in the concentration of paramagnetic compounds. With the goal of developing a spoilage detector that can be used in a tomato processing facility, a γBo = 19.5 MHz single-sided handheld NMR instrument is used. Due to the dominance of diffusion on relaxation measurements made with the single sided instrument, the slope of the amplitude of a spin echo for three different delay times is used to provide a viscosity dependent parameter that permits the differentiation between pristine and spoiled tomatoes.
One-Sided NMR – Non-Invasive Analysis of Tomato Paste