桂花不同品种开花过程中香气活性物质的变化

Changes of Aroma-active Compounds in Different Cultivars of Osmanthus fragrans During Flowering

以12个桂花品种盛花期的花瓣为材料,用气质联用法检测到59种挥发物,其中占主导地位的是萜烯类化合物。选择相对含量均高于0.05%的21种挥发性物质进行主成分分析,12个桂花品种可分成3类,花色为黄色或金黄色的金桂和四季桂(6个品种)为一类,花色为白色或浅黄色的银桂(3个品种)为一类,花色为橙色或红色的丹桂(3个品种)为一类。黄色桂花中以‘柳叶金桂’香气活性物质贡献率最高,达56.75%;白色桂花中以‘厚瓣银桂’贡献率最高,达51.91%;橙色桂花中以‘镉橙丹桂’贡献率最高,达58.88%。以此3个品种为代表材料,用气相色谱—嗅闻技术测定了其开放过程中香气活性物质的变化。结果表明,3个品种在铃梗期都以释放具有罗兰香/木香/果香型的物质为主。初花期到盛花期,橙色花的‘镉橙丹桂’以释放花香型物质为主,白黄色花的‘厚瓣银桂’以释放香草香型物质为主,黄色花的‘柳叶金桂’以释放紫罗兰香/木香/果香型物质为主;到了末花期,‘镉橙丹桂’与‘柳叶金桂’中都是青草香/清新香型的物质占主导地位,而‘厚瓣银桂’中依然是香草香型物质居多,这可能是银桂香气更持久的原因。

The flower petals of 12 Osmanthusfragrans cultivars in full flowering stages were used for Gas Chromatograph - Mass Spectrometer （GC - MS） analysis. The results showed that there were total 59 volatiles detected in 12 cultivars. The volatile compounds of sweet osmanthus were dominated by terpenoids. According to the sum of relative content of main volatiles compounds （〉 0.05%） obtained in principal component analysis （PCA）, sweet osmanthus were clustered into three groups. In yellow color flowers, O. fragrans ＇Liuye Jingui＇ has been found to have the highest cumulative explained variance ratio, which is 56.75%; in white-yellow color flowers, O.fragrans ＇Houban Yingui＇ has been found to have the highest cumulative explained variance ratio, which is 51.91%; and in orange color flowers, O. fragrans ＇Gecheng Dangui＇ has been found to have the highest cumulative explained variance ratio, which is 58.88%. In addition, we selected these three representative osmanthus cultivars with different flower color and fragrance to detect the content of aroma-active compounds during flowering by Gas Chromatography- Olfactometry （GC- O） analysis. The results showed that the three cultivars of O. fragrans released aroma-active compounds with Luolan/woody/fruity odors in the initial flowering stage. From the initial flowering stage to the full flowering stage, O. fragrans ＇Gecheng Dangui＇ with orange color released aroma-active compounds with floral odors~ O. fragrans ＇Houban Yingui＇ with white-yellow color has obvious herbal odors; and O. fragrans ＇Liuye Jingui＇ with yellow color showed more prominent violet/woody/fruity odors. In the final flowering stage, both O. fragrans＇ Gecheng Dangui＇ and O. fragrans ＇ Liuye Jingui＇ showed more prominent obvious green/fresh odors, while O. fragrans ＇ Houban Yingui＇ still has more obvious herbal odors, which may be the reason why people feel this fragrance releasing more constantly.