HS-SPME-GC-MS coupled with OPLS-DA to analyze the effects of extraction methods on volatile aroma compounds of avocado oil

【Objective】The effects of three methods(namely, hot pressing method, supercritical extraction method and aqueous extraction method on the volatile aroma compounds in avocado oil were clarified, which provided data support for the extraction anddevelopment of avocado oil.【Method】Headspace solid phase microextraction-gas chromatography-mass spec-trometry(HS-SPME-GC-MS) coupled with orthogonalpartial least squares discrimination analysis(OPLS-DA) were used to identify the volatile aromas of avocado oil extracted by hot pressing method, supercritical carbon dioxide extraction and water extraction method, and to distinguish between groups and analyze the overall difference.【Result】In total, 80 kinds of volatile aroma compounds were identified from avocado oil extracted by the three methods, and there were 40, 40 and 45 volatile aroma compounds in the oil extracted by hot pressing method, supercritical carbon dioxide extraction and water extraction method respectively. They were mainly hydrocarbons, aldehydes, acids and alcohols. There were 17 kinds of hydrocarbons, 5 kinds of aldehydes, 8 kinds of alcohols and 3 kinds of acids in hot pressing method, accounting for 45.68%, 3.31%, 9.39% and 21.65%, respectively. There were 13 kinds of hydrocarbons, 14 kinds of aldehydes, 8 kinds of alcohols, and 2 kinds of acids were identified in water extraction method, accounting for 28.87%, 26.42%, 15.92%, 19.53%. There were 21 kinds of hydrocarbons, 9 kinds of aldehydes, 4 kinds of alcohols, 1 kinds of acids in supercritical carbon dioxide extraction method, accounting for 42.99%, 12.77%, 7.75%, 20.23%, respectively. OPLS-DA method was used to analyze the volatile aroma compounds produced by three avocado oil samples, which could effectively distinguish avocado oil samples obtained by three methods. There were 56 kinds of symbolic difference compounds existed in three samples, and 13 kinds of special components in supercritical carbon dioxide extraction, such as decane and toluene, and 16 kinds of special components in aqueous method, such as 2-heptene-1-ol and 1-octene-3-ol, and 18 kinds of common components in there methods, such as hexanal, 2-heptenal.【Conclusion】The differences of volatile aroma compounds are analyzed by HS-SPME-GC-MS combined with OPLS-DA, and the potential compounds that form differences are screened out. This method can be used to quickly identify the extraction methods of avocado oil.