Effect of γ-irradiaton on the volatile compounds of licorice (Glycyrrhiza uralensis Fischer)

Abstract

The volatile compounds of non-irradiated and 1, 3, 5, 10 and 20 kGy γ-irradiated roots of licorice (Glycyrrhiza uralensis Fischer) were isolated by simultaneous distillation–extraction (SDE) technique and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 61 volatile compounds belonging to the chemical classes of acid (2), alcohol (16), aldehyde (8), ester (6), furan (2), hydrocarbon (14), ketone (10) and N-containing compounds (3) were identified in non-irradiated licorice. The prime volatile compound of licorice was 2-ethoxy-1-propanol, which makes up to 22.82% of the total composition. Over a dose of 1 kGy, another compound, benzaldehyde appeared, whereas other compounds, 3,5-dimethyl octane and phenethyl alcohol, disappeared at the dose of 20 kGy. Though the content of several volatile compounds increased after γ-irradiation, the content of major volatile compounds such as 4-terpineol, myrtenal, tetramethylpyrazine, hexanoic acid, azulene and p-cymene decreased. In comparison to non-irradiated licorice, 10 kGy dose of irradiation induced the maximum level of total yield of volatile compounds by 12%, but slightly decreased at 20 kGy. Therefore, the application of γ-irradiation is feasible without major qualitative and quantitative loss of volatile compounds when exposed at 10 kGy.