The influence of drying methods on the drying characteristics, quality attributes, moisture migration and...

Fresh carrots are prone to spoilage and deterioration during storage and transportation. The drying can significantly reduce the resources waste caused by spoilage. The exploration of an appropriate drying method for carrots is of great significance. Therefore, the effect of different methods-hot air drying, heat pump drying (HPD), far-infrared drying, heat pump combined with infrared drying (FI-HPD), medium and short-wave infrared drying (MSWID), and vacuum freeze-drying (VFD) on the drying characteristics, nutritional quality and microstructure of carrot slices was performed, and the laws of water migration were explored based on low-field nuclear magnetic resonance (LF-NMR).

MSWID presented the highest drying efficiency, whereas FI-HPD presented the lowest energy consumption. Physically, the VFD sample demonstrated optimal rehydration properties, with scanning electron microscopy confirming a uniformly porous surface morphology, and MSWID samples exhibited superior texture. The LF-NMR results demonstrated moisture migrates from the outside in with outer-layer moisture removal preceding core dehydration and MSWID accelerates the initial moisture transfer rate. Nutritionally, the contents of vitamin C, total phenol, total sugar and β-carotene in the samples dried by VFD were the highest, whereas MSWID and FI-HPD had relatively high contents in specific components.

VFD has obvious advantages in terms of nutrient content and structural integrity, while MSWID and FI-HPD can achieve a good balance among drying efficiency, energy conservation and product quality. These findings provide a theoretical basis for selecting optimal drying methods according to specific product requirements in carrot processing. © 2025 Society of Chemical Industry.