Abstract:

The volatile oil from the bulbs of Allium macrostemon Bunge was extracted by steam distillation with soaking in
hot water and ultrasonic pretreatment. Based on single factor experiments, the yield of volatile oil was selected as response
value and the optimum extraction process was determined through response surface methodology. The chemical constituents
of the volatile oil were analyzed by gas chromatography mass spectrometry (GC-MS). The results showed that the optimal
extraction conditions were soaking in 40 ℃ water with a liquid-to-solid ratio of 4.40:1 (mL/g), ultrasonic pretreatment for
30 min and distillation for 2.2 h. Under these conditions, the yield of volatile oil was 1.030%. Totally 17 compounds were
detected and 14 of them were identified by GC-MS in the extracted volatile oil, together accounting for 93.46% of the total
amount of extracted compounds based on peak area normalization.

Key words: Allium macrostemon Bunge, volatile oil, response surface methodology, gas chromatography-mass spectrometry