Comparative Analysis of Volatile Components in Red Orange Essential Oil Extracted by Two Cold Pressing Processes

Volatile components in red orange essential oil extracted by two cold pressing processes (cup pressing and lime method) were analyzed by gas chromatography quadrupole time-of-flight mass spectrometry (GC-Q/TOF). A total of 93 components were identified, 89 and 84 compounds were identified for the two types of red orange essential oils, respectively. Among the 93 components, there were 29 terpenes, 20 alcohols, 20 aldehydes, 5 esters, 2 ketones, 12 hydrocarbons, and 5 other compounds. There were 80 compounds shared by the two essential oils. The total volatile component content of red orange essential oil by cup pressing method was significantly higher than that by lime method. The highest content of these compounds was terpenes which total content was over 80%. In addition, the compounds with higher content were D-limonene, γ-terpinene, β-myrcene, linalool and α-pinene. According to principal component analysis (PCA), there was a significant difference in the volatile components of the two types of red orange essential oils. The relative odor activity value (ROAV) method indicated that linalool was the most important aroma component of the two red orange essential oils. And the citrus aroma properties of red orange essential oil extracted by cup pressing method was significantly stronger than that extracted by lime method. Linalool, thymol, β-myrcene, D-limonene, citronellal, and γ-terpinene were confirmed to the key aroma components of the red orange essential oils.