Abstract:
In order to explore the effects of different drying processes on the physical properties, active ingredients and antioxidant capacity of pumpkin powder, the vacuum freeze drying (VFD), hot air drying (HAD), and heat pump drying (HPD) were used for drying pumpkin and characterized by SEM, XRD, and FTIR. The results showed that the pumpkin powder of VFD had the smallest particle size (the D
50 was 54.63±0.90 μm), great intact color, the best adsorption and solubility, but the flow and filling properties were poor. The pumpkin powder of VFD had the highest content of active ingredients such as total phenolics (3.56±0.02 mg/g), and the strongest antioxidant capacity, and in HAD and HPD, the total phenol, total flavonoid and the antioxidant capacity of pumpkin powder were higher at 50~60 ℃, while the content of vitamin C,
β-carotene were higher at 40~45 ℃. The pumpkin powder of VFD had smooth surface and internal pores, lower relative crystallinity compared to HAD and HPD, but there was no difference in the types of functional group. The results can provide experimental basis for choosing suitable pumpkin process.