Influence of γ-irradiation and microwaves on the linear unsaturated hydrocarbon fraction in spices

Linear, unsaturated hydrocarbons were detected in spice samples treated with gamma-rays or microwaves. The analyses were performed on aniseed, basil, cinnamon, entire and ground chilli, origano, paprika, black pepper, rosemary and sage. These samples were submitted to different treatments: gamma-irradiation at 5 kGy, gamma-irradiation at 10 kGy, microwaves (frequency of 2450 Mhz for 20 min), and not treated. The identification of linear, saturated, monoenic and dienic hydrocarbons was performed by using off-line liquid chromatography/gas chromatography (LC/GC) mass spectrometry. Unsaturated hydrocarbons were found only in the samples subjected to gamma-irradiation, and 8-heptadecene was found to be a marker for gamma-irradiation, in fact this compound was absent in the untreated and the microwaved samples. On-line, coupled LC-GC was used for the determination of dienic hydrocarbons.