Abstract:In order to explore the water diffusion characteristics of kiwifruit during far-infrared radiation drying, low-field nuclear magnetic resonance (LF-NMR) technology was applied to analyze the influence of radiation temperature on internal water states and moisture migration of kiwifruits during drying. The results showed that drying time decreased significantly with the increasing of radiation temperature, and the ratio of average drying rates at radiation temperatures of 120, 160, 200, 240 and 280 ℃ were 1.001.301.542.002.50 respectively. The effective moisture diffusivity values was in the range of 2.85×10-10~7.03×10-10 m2/s, which could be improved with the increase in radiation temperature. NMR results showed that the water states in kiwifruits included free water, immobilized water and bound water. With the proceeding of drying process, the relative proportion of free water in kiwifruits decreased gradually, and the removal time of free water reduced by 75% as radiation temperature increased from 120 to 280 ℃. At the early stage of drying, some of the moisture with high degree of freedom moved to the moisture with low degree of freedom. Up to the end of drying, bound water was the main component left in the sample. And higher radiation temperature could accelerate the migration and removal of moisture.