Abstract: A new method for the analysis of volatile components from rapeseeds and peanuts was established using improved solvent-free microwave extraction (ISFME)-comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC/TOF-MS). Carbonyl iron powder was used for the solvent-free extraction of volatile oil from rapeseeds and peanuts and its optimized ratio to crop seeds was 1:5 (m/m). A GC×GC/TOF-MS system equipped with DB-5MS and DB-17 columns was used and the modulation period and initial temperature were set as 4 s and 35 ℃, respectively. Compared with the conventional solvent-free microwave extraction (CSFME) method, the improved CSFME (ICSFME) method was time saving, and only 20 min was required for oil extraction from rapeseed and peanut compared with 50 min for the CSFME method. Moreover, the improved CSFME required less energy consumption. The volatile oil extracted by both methods had the same chemical composition as determined by GC×GC/TOF-MS. Many heterocyclic compounds as well as oxidized volatiles (alcohol, aldehydes, ketone, acid, ester and hydrocarbon) and sulfur-containing, nitrogen-containing and benzene ring-containing compounds were identified and heterocyclic compounds were predominant among these compounds. The volatile oil obtained by the ICSFME method showed a higher relative content of oxidized volatiles, which contributed to the formation of more flavor-active substances.

Key words: carbonyl iron powder, solvent-free microwave extraction, oilseed, essential oil, comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry