Reveal the internal moisture changes of white gourd during hot air-drying process using low-field NMR

The moisture content, distribution and state changes of White gourd were studied during hot air-drying process using Low-field nuclear magnetic resonance (LF-NMR). The transverse relaxation time (T-2) inversion spectrum of White gourd was measured at different temperatures during drying process, and the characteristics of internal moisture state and change were analyzed using the LF-NMR. The results showed that T-2 was changed and the moisture of liquidity was reduced during drying process. In addition, the moisture with high degree of freedom changed to the moisture with low degree of freedom during drying. The amplitude of total NMR signal and the moisture content of drying base were a linear relationship during drying. The kinetics of the percentage of bound water and free water were based on exponential function and polynomial function respectively with drying time and different drying temperatures.