Effects of Different Drying Methods on Volatile/Semi-volatile Components and Surface Structure of Sweet Potato Solid Spice

To compare the effects of different drying methods on the solid spice of sweet potato, the fresh sweet potato was taken as the research object, and infrared drying, freeze drying, microwave vacuum drying and vacuum drying were carried out after baking. The volatile/semi volatile components of the solid spice of sweet potato were analyzed and detected by gas chromatography mass spectrometry (GC-MS), principal component analysis was used to explore the impact of different drying methods on volatile/semi volatile components, and scanning electron microscopy was used to explore the impact of different drying methods by its surface structure. The results showed that the content of volatile/semi-volatile substances in dried sweet potato solid flavor from high to low was vacuum drying, microwave vacuum drying, infrared drying and freeze drying, and the highest content was 128.87 μg/g, the main flavor substances include octyl p-methoxycinnamate, palmitoleic acid, geranyl linalool, 5-hydroxymethylfurfural, (9Z)-octadec-9,17-dialdehyde. Compared with the other three drying methods, the surface structure of vacuum dried solid spice had more water evaporation channels and holes, and the structural density was moderate, which had a positive impact on the adsorption capacity and volatile flavor of solid spice. In conclusion, vacuum drying was applicable to the drying and preparation of sweet potato solid spice, which laid a theoretical foundation for the development and application of sweet potato solid spice.