Abstract:To provide the basis for the quality evaluation of citrus peel essential oils and the discovery of special aroma citrus essential oils, the composition and content of volatile substances in the essential oil from the fruit peels of four citrus varieties were analyzed by headspace-solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GCMS), along with relative odor activity values (ROAVs) of the key aroma components in four kinds of citrus peel essential oils. The results showed that a total of 62 volatile compounds were identified from the essential oils of four citrus cultivars, including 13 monoterpene, 14 sesquiterpene, 5 alkanes, 12 alcohols, 8 esters, 4 aldehydes, 3 ketones, 2 ethers and 1 acid. Among the four citrus peel essential oils, the content of monoterpene (83.00%~91.93%) was the highest. According to the compound composition, the four citrus species can be divided into two chemical types: limonene/γ-terpinene type and limonene//3-carene type. Twenty-four key aroma compounds were screened from four citrus peel essential oils by ROAV, among which perillaldehyde was the most important flavor contributor in the essential oils of Citrus meyerii Y. Tan., and there were 10 key aroma substances. Linalool was the most important flavor contributor in the essential oils of Citrus unshiu Marc., Citrus aurantium L. and Citrus wilsonii Tanaka, and there were 12, 20 and 20 key aroma components, respectively. These key aroma components play important roles in the aroma quality of citrus peel essential oils.