Comparative study of essential oil composition of leaves and rhizomes of Alpinia conchigera Griff. at different post- harvest drying periods

Abstract

Essential oils from the leaves and rhizomes of Alpinia conchigera Griff. dried for different times (0 (fresh), 1, 2, 3 and 7 days of drying, respectively) were isolated using hydrodistillation. The chemical composition of oils was analyzed by using GC and GC-MS. The identified components constituted 95.06, 94.51, 94.64 and 91.60% of the leaf oil and 47.71, 64.19, 49.96, 94.47 and 91.56% of the rhizome oil of fresh, 1, 2, 3 and 7 days drying samples, respectively. Thirty four components were identified, among which 31 had not been detected previously. The major constituents in fresh, one, two and three days dried leaves were cyclohexene, 1-methyl-4-(5-methyl-1-methylene-4-hexenyl), while for leaves dried for seven days were 1, 6, 10-dodecatriene, 7 and 11-dimethyl-3-methylene. β-pinene was the major component for fresh and two days dried rhizomes, while 1-methyl-4-(5-methyl-1-methylene-4-hexenyl) was the major constituent for one, three and seven days dried rhizomes. The post-harvest drying period had a positive effect on the oil yield of both leaf and rhizome. The highest oil yield was obtained from leaves dried for 7 days (0.300 v/w) and rhizomes dried for 3 days (0.162 v/w). This study suggests that the yield and content ofessential oils from the leaves and rhizomes of A. conchigera could be increased by drying leaves and rhizomes for 3 and 7 days, respectively. Key words: Alpinia conchigera Griff., essential oil, GC-MS, post-harvest drying, Zingiberaceae.