Composition Analysis Based on Gas Chromatography-Orbitrap-Mass Spectrometry and Evaluation of the Antioxidant Activity of Four Plants Essential Oils

Gas chromatography-orbitrap-mass spectrometry (GC-Orbitrap-MS) was used to identify the compositions of three different sources of chili essential oil, turmeric essential oil, citronella essential oil and fennel essential oil. The content of each component was calculated by the peak area normalization method. Through the forward/reverse matching degree and retention index (RI) of the library comparison, the unknown compound could be confirmed together. The electronic nose technology was used to rapidly analyze the volatile components of essential oils. To compare the antioxidant capacity of essential oils in vitro, DPPH, ABTS free radical scavenging rate and total antioxidant capacity were measured. The results showed that 33 compounds have been identified in chili essential oil Guarea kunthiana A. The major components were capsaicinoids; 95 compounds have been identified in turmeric essential oil,the major components were sesquiterpenoids such as curcumene and longifolene; 137 compounds had been identified in citronella essential oil,the major components were citronellol, citronellol and alpha-humulene etc.; 56 compounds had been identified in fennel essential oil the major component was transanisole. The analysis of the electronic nose radar chart showed that the W1W, W2W and W5S play a key role in distinguishing the volatile gases from different sources of essential oils. According to the results of DPPH and ABTS radical scavenging rate and ferric ion reducing antioxidant power (FRAP), the antioxidant activity from strong to weak were turmeric essential oil, citronella essential oil, chili essential oil and fennel essential oil. Among them, turmeric essential oil from the third source had the strongest antioxidant activity. The IC50 values of DPPH, ABTS radical scavenging activity and FRAP value were 1020.99 μL/L, 464 μL/L and 44.72 μmol Trolox/mL, respectively. The volatile components of the essential oils have been comprehensively analyzed by GC-Orbitrap-MS, which provided theoretical basis and research ideas for the further development of essential oils in food industry.