Bioactive Volatile Compounds from Plants - American Chemical Society

Chapter 19

Volatile Constituents of Roses Characterization of Cultivars Based on the Headspace Analysis of Living Flower Emissions I. Flament, C. Debonneville, and A. Furrer

Downloaded by CORNELL UNIV on June 28, 2012 | http://pubs.acs.org Publication Date: April 6, 1993 | doi: 10.1021/bk-1993-0525.ch019

Research Laboratories, Firmenich SA, P.O.B. 239, CH-1211, Geneva 8, Switzerland The present work is based on the comparative headspace analysis of twenty-seven varieties of living roses. A classification of the volatile constituents into six functional groups including the most abundant and characteristic chemicals is proposed: hydrocarbons, alcohols, aldehydes and ketones, esters, aromatic ethers and other miscellaneous functions. A presentation of the analytical results is given in the form of a stylized flower (exogram): this graphical illustration allows at one glance a symbolization and recognition of odoriferous flowers or any other scenting living plant material. Nature, and in particular the plant kingdom, consists of a complex assembly of production units providing many thousands of odoriferous substances. For insects and humans, the flower is certainly the part of the plant which is the most attractive to the senses of sight and smell. Classical extraction by solvents or vapor distillation of petals inevitably results in the irreversible degradation of a considerable number of their constituents and the isolation of an adulterated perfume. Such concentrates are evidently used for perfume creation but their analysis is not representative for precise analytical work, as the composition is very different from that of the natural starting material. In contrast, dynamic headspace analysis of living flowers is a gentle and convenient technique which allows the enrichment of the most delicate "essences", and the separation and identification of their individual components. Used successfully as early as 1977 for the analysis of jacinth (1) or gardenia (2) volatiles, the method has undergone a tremendous expansion throughout the eighties and is now considered as a routine technique in almost all laboratories working on volatile constituents of odorants (3-9) (5) (6) (7) (8) (9). It is normal that the "mystical and magic" rose, due to its perfectly divine perfume, was the first to become the object of numerous classical analyses, the purpose being to identify the most noble and subtle of its odoriferous components. The task was not straightforward, demonstrated by the fact that, at the turn of this century, only eight constitutionally defined substances had been discovered in rose essence. In 1953 only 20 compounds were known and in 1961 the number had increased to 50. From the start of the sixties, modern analytical techniques resulted in an acceleration in the identification of the volatile components: 200 by 1970 and 400 by 1990. One of the most complete analyses was published by Kovats in 1987 (10) but the story of rose analysis is marked by milestones corresponding to the identification of minor characteristic volatile constituents. For example, the NOTE

: This chapter is dedicated to the memory of Dr. Alan F. Thomas. 0097-6156/93/0525-0269$06.00/0 © 1993 American Chemical Society

In Bioactive Volatile Compounds from Plants; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1993.

270

BIOACTIVE VOLATILE COMPOUNDS F R O M PLANTS Table I. Main constituents of some rose varieties

Cultivar® SOMA MHLLAND MONICA

(1)

(2)

(3)

43.1

(4)

(5)

(6)

(8)

(9)

(10)

(11)

20.9 22.3

21.5

Rosa rugosa rubra Rosagallica Rosamuscosapurpurea

53.9 41.8 29.9 20.6

C H A T E L A I N E de LULLIER

26.1

Rose à parfum de I Hay

23.0

23.2

M A R G A R E T MERRIL C O N C O R D E 92 B A R O N N E de ROTHSCHILD

39.5 48.8 45.1

Rosa damascena Downloaded by CORNELL UNIV on June 28, 2012 | http://pubs.acs.org Publication Date: April 6, 1993 | doi: 10.1021/bk-1993-0525.ch019

(7)

32.9

29.7

YONINA SUTTERS G O L D C O C K T A I L 80 SUSAN A N N ELISABETH of G L A M I S NUAGE PARFUME HIDALGO SYLVIA YOUKISAN GINA LOLLOBRIGIDA PAPAMEOJLJ\ND WHITE SUCCESS

26.5 23.7

26.2 28.8

29.0

59.8 42.0 24.5 20.4 19.3 43.2

22.1 19.4

29.4

67.3 55.8 5 2.5 40.3 29.6

(1) Germacrene-D; (2) (£)-48-Dimethyl-13-7-nonatriene; (3) β-Caryophyllene; (4) Phenylethanol; (5) Geraniol; (6) Citronellol; (7) Hexanol; (8) (Z)-3-Hexenyl acetate; (9) Phenylethyl acetate; (10) Hexyl acetate; (11) Orcinol dimethylether. f

identification of carvone and eugenol methylether in 1949 (11), the structural elucidation and synthesis of rose oxide diastereoisomers in 1959-61 (12,13), the discovery of rose furan in 1968 (14) and of l-p-menthen-9-al in 1969 (15) and, last but not least, the isolation of ionones, dihydro-ionones, β-damascone and βdamascenone in 1970 (16). The importance of such minor components in flavors and fragrances has been highlighted by Ohloff (17). The present work is based on the headspace analysis of 27 varieties of roses, including classical roses and more recent hybrids (Trademark names® are capitalized). The analysis was performed by a technique previously described (18): adsorption on TENAX cartridges, subsequent thermal desorption, separation of constituents by gas chromatography on a wide-bore glass capillary column and identification by mass spectrometry (Finnigan MAT, ITD Mod. 800). Quantification was achieved by integration of the TIC (Total Ionization Current) diagrams. It has been shown by Kaiser (19) that the emission of volatiles in flowers is dramatically time dependent and that rhythmic changes of fragrance composition are observed during the course of diurnal cycles. On the other hand, Mookherjee (3, 20) has pinpointed the chemical differences in the smell between "living" and "dead" flowers: the composition of a picked tea rose is remarkably different from that of the corresponding living rose. For instance, (Z>3-hexenyl acetate which constitutes 20% of the living headspace volatiles, is drastically reduced to 5% in the picked flower, whereas the concentration of 3,5-dimethoxytoluene (orcinol dimethylether) is doubled. As will be shown below we have corroborated these observations, but the changes are strongly dependent on the species and are not always so important. To ensure reproducibility in measurements, sampling of headspace volatiles was systematically performed on living flowers with the same type of cartridge, during the same period of time (8-9 a.m. to 4-5 p.m.) and under an identical air flow.


19.

FLAMENT ET AL.


Table II.

Volatile Constituents of Roses

271

Distribution of functionalities in the headspace constituents of 27 cultivars

Cultivar®

R-H

R-OH

-COOR

Ar-O-

MONICA SONIA MEILLAND CHARLES de G A U L L E Rosa rugosa rubra Rosa muscosa purpurea MARGARET MERRIL Rose à parfum de VHay Rosa gallica WESTERLAND Rosa damascena CHATELAINE de LULLIER BARONNE Ε. de ROTHSCHILD SUITERS GOLD CONCORDE92 COCKTAIL 80 SUSAN A N N HIDALGO YONINA NUAGE PARFUME ELISABETH of GLAMIS JARDIN de B A G A T E L L E PRELUDE SYLVIA YOUKISAN GINA LOLLOBRIGIDA PAPA MEILLAND WHITE SUCCESS

56.3 46.1 40.7

1.8 21.1 3.4 81.0 70.5 62.5 56.5 47.5 45.7 37.9 37.6

5.8 7.2 21.2 3.8 11.2 6.4 23.1 28.1 29.3 45.5 23.0 91.1 75.5 73.2 70.9 59.7 58.1 55.8 48.8 48.6 34.2 30.9 0.7 5.0 18.6 16.2 20.0

13.8 2.3 1.7 0.6 0.4 13.7 0.1

9.6 7.1 2.8 11.1 0.1 0.4 0.2 1.8 2.4 2.4 1.0 0.4 2.5 1.1 4.5 7.1 22.8 7.3 11.6 5.2 5.4 1.4 14.1

7.9 4.1 7.7 24.4 2.4 5.7 21.1 20.4 0.2 29.2 0.3 11.5 31.5 3.7

2.9 0.8 23.1 0.5 14.4 13.9 16.3 3.6 29.7 30.2 17.3 6.1 10.8 17.4 67.3 58.8 53.7 44.8 30.1

Headspace analytical results are usually presented as lists of compounds i n order of their retention times. W e rapidly realized that the critical analysis of such lists is tedious and impractical. Therefore we have preferred a classification o f the identified constituents into six groups according to their chemical functionality: hydrocarbons, alcohols, aldehydes and ketones, esters, phenols and aromatic ethers, and a sixth group including c y c l i c ethers together with miscellaneous compounds. Table I lists the rose varieties i n which one component exceeds 19-20%. Table Π indicates, for the 27 cultivars, the composition with regard to the 4 main functional groups T o symplify the presentation of the results we have chosen a graphical illustration o f a flower with six petals whose individual lengths are proportional to the functionalities of the volatile constituents (Figure 1). The quantities arc expressed in % o f the total amount of volatiles detected in the headspace. O n the basis of our systematic observation o f these "Exhalograms or Exograms" we would like to propose a classification of odoriferous roses consisting of several types:



272

BIOACTIVE VOLATILE COMPOUNDS F R O M PLANTS

Figure 1. "Exogram" showing the distribution of rose headspace volatile constituents according to their chemical functionalities.

Figure 2. Rose varieties of "hydrocarbon type".

Hydrocarbon Types The major functional group of these varieties is represented by terpenic, homoterpenic and sesquiterpene hydrocarbons. Among the varieties examined we found three cultivars whose volatile headspace contains hydrocarbons to the extent of more than 40% (Figure 2): MONICA (Tantau 1986). This rose presents very elegant buds with a copperorange yellow colour. The major volatile components are hydrocarbons: (E)-4,8dimethyl-l,3,7-nonatriene (22.3%), caryophyllene (21.5%), various sesquiterpenes (12.5%), and aromatic ethers (13.8%) (orcinol dimethylether, 10.5%). Some esters are also present: phenylethyl acetate (3.1%), (ZJ-3-hexenyl acetate (1.5%) and hexyl


19. FLAMENT ET AL.

Volatile Constituents of Roses

273

acetate (1.2%). Phenylethanol is only present in small quantities (1.3%). The olfactive contribution of β-ionone (2.0%) is evident


SONIA MEILLAND (syn. SWEET PROMISE, var. Meihelvet, Meilland 1973). This hybrid tea rose has China pink petals with salmon highlights and is distinguished by its pronounced fruity smell (Origin: "ZAMBRA" χ "SEEDLING"). The hydrocarbon group (46.1%) mainly consists of germacrene-D (43.1%) whereas phenylethanol (20.9%) and phenylethyl acetate (5.7%) are the principal alcohol and ester. Miscellaneous minor compounds such as hexanal (0.5%), (Z,)-2-hexenal (0.5%), decanal (0.5%) and anisole (0.6%) are important contributors to the overal odor. CHARLES DE GAULLE (var. Meilanein, Meilland 1975). The volatiles of this mauve-blue rose mainly consist of a multitude of sesquiterpene hydrocarbons (40.7%) including germacrene-D (8.9%), β-caryopyllene (2.1%) and γ-muurolene (2.7%). The typical smell can be explained by the presence of hexyl acetate (11.7%), (ZJ-3-hexenyl acetate (9.4%), a small quantity of citronellol (3.4%) but more probably by trace constituents such as anisole (0.9%) and rose oxides (1.5%). Alcohol Types without Orcinol Dimethylether. The classical "old" varieties of roses contain between 35% and 85% of essential alcohols such as phenylethanol, citronellol, nerol and geraniol, but the cumulative quantity of these alcohols and various esters remain between 75 and 85%. These varieties contain only small quantities of orcinol dimethyl ether. The following five varieties belong to this class (Figure 3): Rosa rugosa rubra. This variety characterized by large, simple red bordeaux petals has a headspace containing 81% of alcohols (phenylethanol: 53.9%, citronellol: 16.8%, geraniol: 5.6%). Only 2.1% of phenylethyl acetate is present. Among the typical trace constituents are benzaldehyde (0.6%), geranial (0.5%), nonanal (0.3%), decanal (0.2%), rose oxides (0.4%) and methyleugenol (0.6%). The "classical" rose smell of this variety is easily explained by the high "basic" alcohol content, with the honey, mild and warm notes of phenylethanol predominating. Rosa muscosa purpurea. This variety is not very different from R. rugosa rubra. It contains 70.5% of alcohols (phenylethanol: 29.9%, geraniol: 20.6%, citronellol: 16.3%). The phenylethyl acetate content is higher (7.8%). The presence of myrcene (6.6%) accounts for a more balsamic, resinous smell. Rose à parfum de l'Hay (Gravereaux 1901). This rose is characterized by red carmine petals and the presence of 56.5% of alcohols (phenylethanol: 23.2%, citronellol: 18.9%, geraniol: 12.5%). Richer in esters (23.1%) than R. mucosa purpurea it contains (ZJ-3-hexenyl (16.6%), citronellyl and neryl acetates which explains the green, fruity and geranium notes of its perfume. Small quantités (2.2%) of hydrocarbons (α-cubebene and (Ej-ocimene) are also present. Geranial (1%) contributes to the lemon smell. Isoamyl acetate (0.2%) and rose oxides (0.1%) are also detected. Rosa gallica. This classical rose, also known as Rose de Provins (var. officinalis) since the 16th century, has bright red petals. Containing 47.5% of alcohols (phenylethanol, 41.8%, nerol, 2.6%) it is relatively rich in esters (28.1%) (geranyl acetate: 18.1%, phenylethyl acetate: 7.7%) and contains a non-negligible quantity of sesquiterpenes (germacrene: 4.4%, bourbonene: 2.1%).


274

BIOACTIVE VOLATILE COMPOUNDS F R O M PLANTS

Rosa damascena. Well known by the perfumers as the origin of Bulgarian rose oils, this classical variety can be included in the first group despite its higher content in esters than alcohols. In line with the other varieties of this group, the volatiles lack the presence of orcinol dimethylether. Alcohols represent 37.9% of the volatiles (phenylethanol: 14.1%, nerol: 11.9%, geraniol: 9.7%) and esters 45.5% ((Z)-3hexenyl acetate: 29.7%, phenylethyl acetate: 5.8%, hexyl acetate: 5.1%). The good balance between characteristic alcohols and esters (total: 83.4%) accounts for the quality of its essence. Geranial is present at a significant level (1.1%).


Alcohol Types containing Orcinol Dimethylether (Figure 4) M A R G A R E T MERRIL (Harkness 1978). This floribunda waxy white flower with a nuance of satin-like pink color is considered as the sweetest and most deliciously perfumed white flower (Origin: "SEEDLING" χ "PASCALI"). Very rich in alcohols (62.5%) its headspace surprisingly contains hexanol as the main constituent (39.5%), followed by citronellol (16.3%), phenylethanol (3.7%) and geraniol (2.3%). The principal ester is hexyl acetate (5.2%). Hydrocarbons are: βcaryophyllene (4.2%), β-pinene (1.6%) and limonene (0.5%). A small quantity of rose oxides (0.9%) is also present. WESTERLAND (W.Kordes 1969). Flower with pink petals, yellow at the base. The major group of volatiles is made up of alcohols (45.7%): nerol (17.2%), phenylethanol (14.3%) and geraniol (14.2%). Among the esters (29.3%) the presence of phenylethyl acetate (16.0%), hexyl acetate (4.6%), geranyl acetate (4.3%) and neryl acetate (2.7%) should be mentioned. Other minor but olfactively important constituents are: methyleugenol (2.9%), benzaldehyde (0.05%) and βionone (0.05%). CHATELAINE DE LULLIER (var. Meipobil, Meilland 1987). This large pink flower with silvery tones is nicely balanced withrespectto alcohols (37.6%), esters (23.0%) and aromatic ethers (23.1%); the main constituents being: phenylethanol (26.1%), citronellol (11.5%), phenylethyl acetate (9.0%), (Z)-3-hexenyl acetate (6.8%), geranyl acetate (2.3%) and orcinol dimethylether (23.0%). Ester Types "Ester" varieties are those whose total ester headspace content is higher than 30%. Nearly all of them contain moderate quantities of alcohols (

Bioactive Volatile Compounds from Plants - American Chemical Society

Recommend Documents