Analysis of Volatile Organic Compounds in Olive Oil of ‘<i>Koroneiki</i>’ with Different Maturity Indices by GC-IMS

This study aims to determine the optimal harvest period of olives by distinguishing the olive oils with different fruit maturity indices (MIs). Gas chromatography ion-mobility spectrometry (GC-IMS) technology was employed to qualitatively and differently analyze the volatile organic compounds (VOCs) of olive oil extracted from eight MIs of 'Koroneiki' olive fruits, harvested in Longnan City, Gansu Province, China. The results showed that 40 signal peaks were isolated in the eight olive oils with different MIs, and 33 VOCs were identified. These include alcohols (7 kinds), esters (7 kinds), aldehydes (6 kinds), ketones (5 kinds), acids (2 kinds), olefins (2 kinds), and other compounds (4). A total of 20 differential markers for key flavors, with variable importance in the projection (VIP) > 1, were screened out by orthogonal partial least squares - discriminant analysis (OPLS-DA). The results showed that the olive oil samples of the 7th maturity index (QJ7), QJ8, and QJ5, QJ6 have significant differences from the other four olive oils. This suggests that olive oils with different maturity indices can be effectively distinguished.