Aroma components of different flower organs of two Dendrobium Sw. varieties

Abstract

[Objective] This paper compared differences in floral components and its main aroma components in two Dendrobium Sw. varieties, in order to provide scientific foundation for cultivating new varieties of fragrant Dendrobium Sw.

[Method] D. parishii with strong fragrance and Dendrobium Zhenzhu with light fragrance were selected as research objects, headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was utilized to analyze the types and relative content of aroma components in different flower organs (sepals, lips, petals, and gynostemium).

[Result] A total of 96 volatile components in 7 categories were detected, with only 4 components in common (1-hexanol,4,7-dimethyl-4-octanol, trans-2-octen-1-ol and hexanal) between the 2 varieties. A total of 37 volatile compounds were detected in 4 different flower organs of D. parishii, including 11 aldehydes, 8 ketones, 5 alkenes, 4 alcohols, 4 esters, 2 alkanes and 3 other compounds, with 14 shared components. The main components of sepals were hexanal (28.09%), trans-2-nonenal (14.00%) and 2-pentadecanone (13.66%), while the main components of petals were hexanal (24.50%), trans-2-octenal (13.23%) and 2-pentylfuran (12.69%). The main components of the lips were 2-pentadecanone (29.04%), 2-tridecanone (12.71%) and hexanal (10.48%). The main components of gynostemium were the same as those of the lips, but the contents were different. The relative contents of 2-pentadecanone, hexanal and trans-2-nonenal were high, indicated strong fragrance. A total of 63 volatile compounds were detected in 4 different flower organs of Dendrobium Zhenzhu, including 26 olefins, 15 alcohols, 7 esters, 3 alkanes, 4 ketones, 2 aldehydes and 6 other compounds, with 11 shared components. Among them, the olefins presented the highest relative content, which mainly in D-limonene, γterpinene, caryophyllene and β-myrcene, formed a clear and sweet aroma. The major components in petals were D-limonene (20.04%), 1-hexanol (12.56%) and caryophyllene (10.93%); those in sepals were D-limonene (40.60%), β-myrcene (7.81%) and 3-carene (7.63%); those in lips were D-limonene (22.92%), 1,3,3-trimethyl-tricyclo [2.2.1.0 (2,6)] heptane (18.99%) and (Z)-3,7-dimethyl-1,3,6-octadecane triene (10.92%); those in gynostemium column were D-limonene (48.59%), α-pinene (12.62%) and β-myrcene (11.75%).

[Conclusion] There are great differences in the number and relative content of volatile components between D. parishii and Dendrobium Zhenzhu, and the composition of aroma components is complex; 2-pentadecanone is the main aroma component in the floral organs of D. parishii, and D-limonene is the main aroma component in the floral organs of Dendrobium Zhenzhu.

Abstract

摘要：【目的】 对比2种石斛花香成分的差异及其主要香气成分, 为培育香型石斛新品种提供科学依据。 【方法】以 浓香型紫瓣石斛和清香型珍珠石斛为试验材料, 采用顶空固相微萃取结合气相色谱—质谱联用 (HS-SPME-GC-MS) 技术对不同花朵部位 (萼片、唇瓣、花瓣和蕊柱) 的香气成分种类及相对含量进行分析。 【结果】2种石斛检测到7类、96 种挥发性成分, 共有成分仅4种 (正己醇、4,7-二甲基-4-辛醇、反式-2-辛烯-1-醇和己醛) 。紫瓣石斛4个花器官中共检 测到37种挥发性化合物, 包括醛类11种、酮类8种、烯类5种、醇类4种、酯类4种、烷类2种及其他类3种, 共有成分14种; 萼片主要成分是己醛 (28.09%) 、反式-2-壬烯醛 (14.00%) 和2-十五烷酮 (13.66%), 花瓣主要成分是己醛 (24.50%) 、反 式-2-辛烯醛 (13.23%) 和2-戊基呋喃 (12.69%), 唇瓣主要成分是2-十五烷酮 (29.04%) 、2-十三酮 (12.71%) 和己醛 (10.48%), 蕊柱主要成分与唇瓣相同, 含量有所差异; 化合物中2-十五烷酮、己醛和反式-2-辛烯醛相对含量较高, 香 味浓郁。珍珠石斛4个花器官中共检测到63种挥发性化合物, 包括烯类26种、醇类15种、酯类7种、烷类3种、酮类4种、 醛类2种及其他类6种, 共有成分11种; 其中烯类相对含量最高, 烯类以D-柠檬烯、γ-松油烯、石竹烯和β-月桂烯为主, 香味清甜; 花瓣主要成分是D-柠檬烯 (20.04%) 、正己醇 (12.56%) 和石竹烯 (10.93%), 萼片主要成分是D-柠檬烯 (40.60%) 、β-月桂烯 (7.81%) 和3-蒈烯 (7.63%), 唇瓣主要成分是D-柠檬烯 (22.92%) 、1,3,3-三甲基-三环［2.2.1.0 (2,6) ］ 庚烷 (18.99%) 和 (Z)-3,7-二甲基-1,3,6-十八烷三烯 (10.92%), 蕊柱主要成分为D-柠檬烯 (48.59%) 、α-蒎烯 (12.62%) 和 β-月桂烯 (11.75%) 。 【结论】紫瓣石斛和珍珠石斛挥发性成分数量及相对含量存在明显差异, 香气成分组成较复杂; 2-十五烷酮是紫瓣石斛花器官的主要香气物质, D-柠檬烯是珍珠石斛花器官的主要香气物质。