Study On The Volatile, Characteristic Floral Fragrance Components Of Chinese Cymbidium

The main and characteristic fragrance components that defined Chinese cymbidium, C. faberi, C. ensifolium, C. Kanran, C. goeringii and tropical orchids, Phalaenopsis , Brassia and more, were studied using gas chormatography/mass spectrometry (GC/MS) method, by the qualitative and quantitative analysis.In this study, sampling methods which were suitable for analysis the fragrance components in cymbidium was screened and established. Through analysis and comparison the differences of volatile components among Chinese cymbidium representatives, and the differences between Chinese cymbidium and tropical orchid, characteristic fragrance components in Chinese cymbidium were definited preliminary. Moreover, the affects of extraction time, extraction temperature, different florescence and flower color in determining the cymbidium volatile components and the differences of components were analyzed and compared.The following conclusions were made from the above studies.1. According to the characteristics of fragrance intensity and volatility in cymbidium, three collecting methods, Solid Phase Microextraction (SPME), Thermal Desorption Cold Trap injector (TCT) and Purge and Trap(P&T), were compared by experiments, with determination of SPME being given priority to TCT as effective method collecting for volatile components of cymbidium. In this study, the affects of fibers, extraction time on analysis fragrance components of cymbidium were analyzed and compared. The optimum extraction condition was: extracting 60min by 100μmPDMS fiber.2. The differences of volatile components, among Chinese cymbidium and between Chinese cymbidium and tropical orchid, were analyzed. Through collecting, detecting diverse samples, the results showed that 99 kinds of volatile components were present in Chinese cymbidium, in which ester compounds were with high relative content. As well as 113 kinds of volatile components were detected in tropical orchid, terpenoid compounds with rich species and high relative content.It is important that methyl jasmonate, cyclopentaneacetic acid, 3-oxo-2-(2-pentynyl)-, methyl ester and compound C were widespread with high relative content in Chinese cymbidium, but they were not detected in tropical orchid. This phenomenon pointed out that ester compounds were the main or important factors which created the fragrance discrepancy between Chinese cymbidium and tropical orchid, and they may be the characteristic fragrance components.3. There are obvious difference in the flower color of populations of wild C. faberi and C. Kanran in nature. The wild C. faberi has colors in green, yellow-purple, yellow-green, purple and others. The C. Kanran has colors in green, purple and others.. In this study, the preliminary analysis and comparison were made on the volatile components of same species Chinese cymbidium with different color.1) The volatile components in yellow-purple and green flower C. faberi were analyzed by using SPME-GC/MS at normal temperature. The results showed that there were 25 components in yellow-purple C. faberi and 23 components in green C. faberi, as well as 17 components in both color flower C. faberi, 8 kinds of special components in yellow-purple C. faberi, and 6 kinds of special components in green C. faberi. There were no significant differences in the main volatile components between the two species of C. faberi., However,ocimene and geranylacetone were found more in yellow-purple C. faberi, Z,Z,Z-1,4,6,9-nonadecatetraene and methyl-2,5-octadecadiynoate were found more in green C. faberi.2) The volatile components in four different color flower C. faberi were analyzed by using TCT-GC/MS. Endo tricyclo[5,2,1,0(2,6)] decane, methyl jasmonate A, methyl jasmonate B, farnesol, 2-propyl-1-pentanol and etc, a total of 48 components were detected in yellow-purple C. faberi. Farnesol, methyl jasmonate B, endo tricyclo[5,2,1,0(2,6)] decane, ocimene, isophorone, 2-propyl-1-pentanol and etc, a total of 40 components were detected in green C. faberi. Isophorone, cyclopentaneacetic acid, 3-oxo-2-(2-pentynyl)-, methyl ester, farnesol, methyl jasmonate B and etc, a total of 31 components were detected in yellow-green C. faberi. Farnesol, 2-propyl-1-pentanol, endo tricyclo[5,2,1,0(2,6)] decane, methyl jasmonateB, ocimene, linalool and etc, a total of 24 components were detected in purple C. faberi. The differences of the relative contents of limonene, longifolene, farnesene, and others, were not obvious. On the contrary, there were obvious differences in relative contents in isophorone, farnesol, linalool, and ocimene.3) The volatile components in different color flower C. Kanran were analyzed by using SPME-GC/MS at normal temperature. There were 22 volatile components detected in green flower C. Kanran and 18 volatile components in purple flower C. Kanran. The species of ester components in green flower C. Kanran were more than purple flower C. Kanran. The changes of the contents of 2,5-octadecadiynoic acid, methyl ester , Z,Z,Z-1,4,6,9-no- adecatetraene in green flower C. Kanran and 4,7-dimethyl-4-octanol, geranyl acetone in purple flower C. Kanran were maximal, it may be the main reason for the fragrance differences between different color C. Kanran.4. According to the affects of florescence, cymbidium fragrance releasing and other factors, C. faberi florescence were divided into five stages. SPME-GC/MS method was used to analyze the changes of volatile components at different blooming stages of yellow-purple C. faberi, green C. faberi and C. ensifolium. Moreover, the daily changes of volatile components in yellow-purple C. faberi were analyzed by using TCT-GC/MS method.1) The analysis results of yellow-purple C. faberi florescence indicated that: Ocimene andα-farnesene were the main fragrance components at bud stage. (E,E)-Farnesol, methyl jasmonate and compound C were the main fragrance components at half opening stage. At full opening stage, the relative content of(E,E)-farnesol> methyl jasmonate>ocimene were high. At the end of full opening stage, the relative content of(E,E)-farnesol>compound C>ocimene were high. There were 10 components detected in the at the decay stage, they were high in alkanes relative content and had variety of species, ester compounds were not detected. The synthesis and release of ocimene increased at half opening stage, that of geranylacetone increased after half opening stage. (E,E)-Farnesol had the highest content in the half opening stage, full opening stage and decay stage, it was an important componentin yellow-purple C. faberi fragrance was more.2) The analysis results of green C. faberi florescence indicated that: Trans-ocimene and linalool were the main fragrance components at bud stage. The relative content of compound C and methyl jasmonate was up to 70% at half opening stage. The relative content of ocimene and compound C reached to 60% at full opening stage. At the end of full opening stage, the relative content of farnesol and compound C reached to 50%.There were 8 compounds detected at the decay stage, which had little affects to the fragrance. The relative content of ocimene changed obviously with the florescence, it indicated that the synthesis and release of ocimene is highly correlated. Compound C, was existed in half opening stage, full opening stage, end of full opening stage as main component, and less affected by florescence, which was the main component in green C. faberi fragrance.3) The volatile components of C. ensifolium during different florescence: The variation of the total content of volatile compounds of C. ensifolium was as follow. Since bud stage, the total content of volatile compounds increased with time. The total content of volatile compounds became to descend after reaching the peak. However, the variation of the total content was not obvious at the 2nd and the 4th day. In the all blooming period, the contents of pentadecane and cineole almostly didn't change. It indicated that pentadecane and cineole didn't directly affect the fragrance of the flower of C. ensifolium. There were 5 kinds of esters,such as methyl jasmonate B,cyclopentaneacetic acid, 3-oxo-2-(2-pentynyl)-, methyl ester detected at half opening stage. The content of them had been asceding until the 4th day of florescence then started descending. 12-Oxatricyclo[4.4.3.0(1,6)]tridecane-3, 11-dione, Z,Z,Z -1,4,6,9-nonadec- atetraene were also the main volatile components. The content of the 3 volatiles reached to the peak at the 2nd day of blooming then started descending.4) The daily changes of the volatile components of C. faberi: At 15:00, the content of alcohols was higher than other times, while there was a higher content of volatility in esters at about 11:00. Two kinds of methyl jasmonate were detected, which were called methyl jasmonate A and B. They both had high content of volatility in the day. The content of volatility of methyl jasmonate A was higher in the morning than in the afternoon, while methyl jasmonate B was reverse to jasmonate A. There was no an obvious changes in the content of volatile of longifolene. The content of volatile of ocimene was 4-5 times in the morning than in the afternoon. The contents of aldehydes,ketones and other components were low in all of the volatile components of C. faberi, and the variations were not obvious.