Measuring thermal properties of oilseeds using time domain nuclear magnetic resonance spectroscopy

•Time domain nuclear magnetic resonance spectroscopy has been used to obtain information about intact oilseeds.•Time Domain Nuclear Magnetic Resonance can measure seed's temperature.•Nuclear Magnetic Resonance can measure thermal properties.

A time domain nuclear magnetic resonance (TD-NMR) method to measure temperature and thermal diffusivity of intact oilseeds is demonstrated. The method to measure temperature of intact seeds is based in a calibration curve between the transverse relaxation time (T2) of vegetable oil in the seed, with temperature. The thermal diffusivity (λ) was calculating using the time constant of temperature decay, when the spherical sample was placed in a low temperature bath and its radius. The proof of principle was demonstrated with spherical samples of glycerol and ethylene glycol with known λ. Thermal diffusivity of the macadamia nuts calculated by this method were approximately 0.9 × 10−7 m2 s−1, similar to these values measured by thermocouple method (0.6 × 10−7 m2 s−1), Dickerson method (0.8 × 10−7 m2 s−1) and the λ reported in literature for nuts and oilseeds.