Abstract:Freeze-dried fruits and vegetables are rich in vitamins and minerals.In this study，low field nuclear magnetic resonance（NMR）was used to analyze the internal moisture changes of carrot chips during drying.The microstructure of carrot chips was observed using a stereomicroscope.The change in quality of the carrot chips was studied judging by the texture，volume，carotene content，color change，rehydration ratio and other aspects.The results showed that in the process of vacuum freeze-drying，water was lost in three states.In the early stage of drying，the levels of free water decreased dramatically，in the late stage，the semi-combined water and combined water were removed.The brightness of the pseudocolor image gradually decreased，and the image gradually blurred from the outside in.Throughout the drying time，the carrot chips developed a loose and porous structure，and their brightness increased significantly，while the hardness，the volume，and carotene levels decreased.When the freeze-drying time was increased，the rehydration rate gradually increased，and the carrot chips had excellent rehydration properties.