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The aroma components and key aroma components from citrus peels with six different aroma types were analyzed to provide the basis for quality evaluation of citrus peels and development of special aroma citrus essential oils. The volatile components of essential oil from citrus peel were analyzed by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GCMS), and the key aroma components were calculated by relative odor activity value (ROAV). The results showed that 75 volatile compounds were identified from the essential oils of 6 citrus cultivars. The content of monoterpene (73.82%~91.19%) was the highest, followed by alcohols (4.32%~12.63%) and sesquiterpene (1.51%~10.20%), and these components interact to form a unique aroma of citrus peel. There were 23 compounds common in essential oils of six citrus peel, and their contents reached about 80.33%~94.59%. According to the composition of the compounds, the six essential oils can be divided into three types: Limonene, limonene/γ-terpene and limonene/3-carene. ROAV analysis showed that linalool was the most important flavor component of six essential oils from citrus peel. In addition, the key aroma components of essential oils from Quzhou, Ziyang, Qingpi, Nanfeng, Jinqiuchatang and Hongmeiren were significantly different, and there were 8, 14, 11, 8, 13 and 18 aroma components, which would play an important role in the unique aroma formation of citrus peel essential oil.

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.