ORIGINAL ARTICLES
Analysis of Floral Scent Compounds and Classification by Scent Quality in Tulip Cultivars
2013 Volume 82 Issue 4 Pages 344-353
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2013 Volume 82 Issue 4 Pages 344-353
Floral scents of tulip (Tulipa L.) cultivars are highly diverse, ranging from citrus, honey, or grassy to medicinal. To clarify the diversity of the quality of tulip floral scents, we analyzed the scent compounds of 51 tulip cultivars with characteristic scents. The major scent compounds were five monoterpenoids (eucalyptol, linalool, d-limonene, trans-β-ocimene, and α-pinene), four sesquiterpenoids (caryophyllene, α-farnesene, geranyl acetone, and β-ionone), six benzenoids (acetophenone, benzaldehyde, benzyl alcohol, 3,5-dimethoxytoluene (DMT), methyl salicylate, and 2-phenylethanol), and five fatty acid derivatives (decanal, 2-hexenal, cis-3-hexenol, cis-3-hexenyl acetate, and octanal). Tulip cultivars were classified into nine groups according to the composition of major scent components and sensory assessment of a living flower: group 1, anise; group 2, citrus; group 3, fruity; group 4, green; group 5, herbal; group 6, herbal-honey; group 7, rosy; group 8, spicy; and group 9, woody.
Ever since tulips (genus: Tulipa) were introduced into Europe from Turkey in the middle of the sixteenth century, thousands of hybrids have been bred. In The Classified List and International Register of Tulip Names, 5600 tulips, including nearly 130 wild species, are listed, and 2600 tulip species are cultivated all over the world (Kunishige, 2002; van Scheepen, 1996). In Japan, cut flowers of about 400 tulip cultivars grown in the greenhouse are marketed from December to March. In April, many tulips add color to spring gardens, and tulip festivals are held in flower parks at many locations in Japan. Tulips, the flowers of spring, are one of the most popular flowers in Japan.
Tulip hybrids vary widely in color and shape and are classified into 15 divisions, according to when they bloom, their height, and the shape of the flower. On the other hand, little is known about tulip scent, and only about 50 cultivars in the tulip list are identified as fragrant tulips (van Scheepen, 1996). In fact, there is great variation in odor strength, although floral scents are emitted by most cultivars.
Tulip floral scent compounds have been analyzed in hexane extracts from the petals of 11 cultivars (Ikeda et al., 1994, 1996; Nakagawa et al., 1995), but data reflecting the scent of a living flower were not obtained. The emitted floral scent of tulips varies considerably ranging from citrus, honey-like, or green to medicinal. To clarify the diversity of the quality of tulip floral scents, we analyzed the emitted scent compounds of 51 tulip cultivars with characteristic scents.
Twenty-nine tulip cultivars were grown in a field at the Horticultural Research Institute of Toyama Prefectural Agricultural, Forestry and Fisheries Research Center or NARO Institute of Floricultural Science under natural conditions, and flowers of these cultivars were cut. Twenty-two cultivars were marketed cut flowers and were used after flowering in a laboratory at about 20°C (Table 1).
| DL*1 | Angelique | T | Harutenshi | DL | Orange Princess*2 |
| SE | Apricot Beauty*2 | DH | Hatsuzakura | DH | Orange Queen*2 |
| FR | Barbados*2 | SL | Ile de France*2 | SL | Pink Diamond*2 |
| L | Ballerina*2 | T | Jan van Nes*2 | L | Pretty Woman*2 |
| DE | Bellona*2 | DH | Kikomachi | SL | Prince of Nippon |
| SL | Beniyutaka | T | Koiakane | SL | Sakura |
| SL | Benizukin | DH | Koki | DH | Shirayukihime |
| T | Capri*2 | T | Lady Margot*2 | T | Strong Gold*2 |
| T | Carnival de Rio*2 | DE | Largo*2 | DH | Tender Beauty*2 |
| SE | Diana | T | Leen van der Mark*2 | T | Tonami City |
| T | Desire | SL | Magier | DL | Upstar |
| DL | Finola*2 | T | Merry Widow*2 | F | Usugesho |
| SE | General de Wet | DE | Monsella | DE | Viking*2 |
| DH | Golden Apeldoorn*2 | DE | Monte Carlo*2 | L | Wedding viel |
| DH | Goromaru | DE | Montreux | SL | Wisteria Maid |
| DL | Harunoawayuki | SL | Murasakizuisho | T | Yukitsubo |
| DL | Harunohimatsuri | T | Orange Bouquet | L | Yumenomurasaki |
An absorbent (Twister, a magnetic stir bar coated with a partitioning phase of 100% polydimethylsiloxane; Gerstel Inc., Mülheim, Germany) was used for collecting floral scents. A Twister was clipped to the inside of a petal so it would not touch the anthers and the petals. The whole flower was covered with a transparent wrapper (Saran Wrap; Asahi KASEI, Tokyo, Japan) and the Twister absorbed the scent compounds for two hours (Fig. 1). Collected samples were stored in a tightly closed container until analysis.
Sampling floral scent of tulip. A, a Twister was fixed to the petal with a clip; B, the whole flower was covered with a transparent wrapper.
The trapped volatiles were analyzed using a GC-MS apparatus (Agilent 5973; Agilent Technologies, Wilmington, DE, USA) coupled to a Thermal Desorption System 2 (Gerstel Inc., Linthicum, MD, USA) (Oyama-Okubo et al., 2011). The thermal desorption conditions were heating from 30°C to 220°C at 60°C·min−1, holding for 10 min at 220°C, and cryofocusing at −50°C in the cold injection system (CIS; Gerstel Inc.). Following thermal desorption from a Twister, the CIS was heated to 300°C at a rate of 12°C·s−1 in splitless mode to transfer the analytes to a gas chromatograph (GC) equipped with a capillary DB-WAX column (30 m length, 0.25 mm i.d., 0.25 μm film thickness; Agilent Technologies). Helium was used as the carrier gas at a flow rate of 1.0 mL·min−1. The temperature of the oven was set to 45°C for 2 min, then increased by 3°C·min−1 to 220°C, and kept at this temperature for 10 min. Interface and ion source temperatures were 280°C and 250°C, respectively. Ionization was performed in electron impact mode at 70 eV, and a mass scan range of 30–350 m/z was monitored. Volatile compounds were identified using the Wiley 9th/NIST 2011 library search system provided with the GC-MS software (Agilent Technologies) and crosschecked by comparing the mass spectra and retention times with authentic samples analyzed under the same conditions.
Sensory assessment of scent compounds and living flowersThe sensual features of major scent compounds comprising each flower scent were derived by referring to Burdock (2010), Nakajima (1995), and Nakamura (1987). The sensual features of 3 fresh flowers of each cultivar were evaluated by the authors before sampling emitted volatiles. Odor description terms of fresh flowers were derived by referring to Hikichi (2003) and Horiuchi (2006).
Classification of tulip floral scentsMajor scent compounds were divided by their odor descriptions, and the ratios of scent compounds for each group were added. Then, tulip cultivars were divided by the sum of values and sensory assessment of each cultivar.
We selected 51 cultivars of tulip that have characteristic floral odors. About 130 scent compounds ranging from terpenoids and benzenoids to fatty acid-derivatives were detected. The major scent compounds were five monoterpenoids (eucalyptol, linalool, d-limonene, trans-β-ocimene, and α-pinene), four sesquiterpenoids (caryophyllene, α-farnesene, geranyl acetone, and β-ionone), six benzenoids (acetophenone, benzaldehyde, benzyl alcohol, 3,5-dimethoxytoluene, methyl salicylate, and 2-phenylethanol) and five fatty acid derivatives (decanal, 2-hexenal, cis-3-hexenol, cis-3-hexenyl acetate, and octanal) (Table 2). Major scent compounds were divided into 8 groups (anise, citrus, fruity, green herbal, rosy, spicy, woody) based on their odor descriptions (Table 3). Then, based on the total amount of ratios of scent compounds for each group and sensory assessment of floral scent of a living flower, the scents of tulip cultivars were classified into 9 groups (Table 4). In addition, total emitted amounts were shown by the peak area in a GC-MS chromatogram for quantitative comparison of floral scent compounds (Fig. 2). The details of each group are as follows.
| Angelique | Apricot Beauty | Barbados | Ballerina | Bellona | Beniyutaka | Benizukin | Capri | Carnival de Rio | Diana | Desire | Finola | General de Wet | Golden Apeldoorn | Goromaru | Harunoawayuki | Harunohimatsuri | Harutenshi | Hatsuzakura | Ile de France | Jan van Nes | Kikomachi | Koiakane | Koki | Lady Margot | Largo | Leen van der Mark | Magier | Merry Widow | Monsella | Monte Carlo | Montreux | Murasakizuisho | Orange Bouquet | Orange Princess | Orange Queen | Pink Diamond | Pretty Woman | Prince of Nippon | Sakura | Shirayukihime | Strong Gold | Tender Beauty | Tonami City | Upstar | Usugesho | Viking | Wedding veil | Wisteria Maid | Yukitsubo | Yumenomurasaki | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Monoterpenoids | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Eucalyptol | —* | 14.7*2 | — | 0.6 | — | — | — | — | — | — | — | — | 3.0 | 12.0 | — | — | — | — | — | — | — | — | — | — | 9.2 | 60.8 | — | 15.9 | — | 16.7 | 19.3 | — | — | — | — | 5.8 | — | 9.7 | 27.7 | — | — | — | 0.8 | — | — | — | 23.1 | 1.3 | — | — | 3.0 |
| Linalool | — | 32.0 | 13.2 | — | — | 18.7 | 1.0 | — | — | — | 51.8 | — | 0.6 | 14.3 | — | — | — | — | 2.9 | 2.7 | — | — | 0.3 | 19.4 | 32.9 | — | — | — | — | — | 0.3 | — | — | — | — | 8.3 | 3.2 | — | — | — | — | 0.5 | — | — | — | — | 6.1 | — | — | — | — |
| Linalool oxide | — | — | — | — | — | — | — | — | — | — | 12.4 | — | — | — | 2.3 | — | — | — | — | — | — | — | — | 0.3 | 0.7 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| d-Limonene | — | 14.0 | — | — | — | 1.4 | 0.6 | — | — | — | — | — | 1.8 | 19.0 | — | 6.5 | 1.3 | 2.7 | 0.2 | 3.1 | — | — | — | 2.3 | 10.3 | 20.0 | — | 13.1 | — | 7.8 | 9.7 | — | 4.3 | — | 4.1 | 12.6 | — | — | 18.2 | 0.3 | — | — | 0.4 | — | — | — | 14.8 | 4.8 | 3.2 | — | 3.1 |
| trans-β-Ocimene | — | 0.2 | 60.0 | — | 0.9 | 49.7 | 5.1 | — | 83.6 | 0.2 | 0.4 | 39.7 | 4.5 | 1.4 | — | — | 28.3 | 15.4 | — | 5.6 | 0.6 | 0.6 | 68.5 | 0.9 | 0.6 | — | 84.4 | — | 36.2 | — | 0.3 | 0.3 | — | 76.9 | 4.2 | 2.5 | 3.5 | — | — | 45.1 | 45.0 | 48.8 | 0.7 | — | 0.9 | 82.7 | 2.1 | — | 32.0 | — | 12.3 |
| α-Pinene | — | 13.7 | — | — | — | — | — | — | — | — | — | — | 2.3 | 12.7 | 1.1 | — | — | — | 5.7 | — | — | — | — | 2.7 | 25.4 | 12.4 | — | 4.7 | — | — | 2.8 | — | — | — | — | — | — | — | 19.8 | — | — | — | 0.6 | — | — | — | — | — | 1.2 | — | 1.1 |
| α-Terpineol | — | 8.9 | — | — | — | — | — | — | 7.6 | — | — | — | 2.5 | 2.1 | — | — | — | — | — | — | — | — | — | — | 9.9 | 1.4 | — | 11.0 | — | — | 20.6 | — | — | 0.4 | — | 1.7 | — | — | 9.1 | — | — | — | — | — | — | — | 14.1 | — | — | — | 1.4 |
| Others | — | 2.4 | 7.2 | 3.0 | 0.9 | 14.3 | — | — | — | — | 6.4 | 3.0 | 2.0 | 5.0 | — | — | 2.7 | 0.5 | — | 3.8 | — | — | 24.8 | 6.7 | 3.6 | 3.2 | 4.9 | 5.9 | 2.0 | — | 2.6 | 0.4 | — | 4.5 | — | 5.2 | — | — | 0.7 | 10.0 | 4.1 | 8.9 | 0.1 | — | — | 11.8 | 3.1 | 0.2 | 4.2 | — | — |
| Sesquiterpenoids | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Caryophyllene | — | 1.1 | 6.4 | — | 7.4 | — | — | 1.9 | — | — | 0.8 | 0.8 | 0.9 | 2.4 | — | — | — | 9.7 | — | 25.7 | 3.8 | 0.4 | — | 1.4 | — | — | — | — | 0.4 | 4.1 | 1.3 | 7.4 | 2.1 | 0.9 | 1.1 | — | 2.0 | — | 1.9 | 4.1 | — | — | 0.6 | 19.7 | 4.0 | — | 0.0 | 1.0 | 0.9 | 1.4 | 4.7 |
| α-Farnesene | — | — | — | — | — | — | 47.3 | — | — | — | — | — | 8.0 | — | — | — | — | — | 0.4 | — | — | — | 2.1 | — | — | — | — | — | — | — | — | 1.0 | — | — | — | — | — | — | 0.9 | 0.9 | 25.9 | — | 1.2 | — | — | 3.3 | 0.5 | 0.3 | 43.1 | — | — |
| Geranyl acetone | — | — | 4.0 | — | 2.2 | — | 29.7 | — | — | — | 1.7 | — | 3.6 | — | — | — | — | — | 1.2 | 2.5 | — | — | — | — | — | — | — | — | — | — | — | 1.0 | — | 0.3 | — | — | — | — | — | 1.6 | 2.7 | 5.5 | — | 45.0 | — | — | — | — | — | — | — |
| Dihydro-β-ionone | — | — | — | 14.4 | — | — | — | — | — | — | — | — | 2.2 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| β-Ionone | — | — | — | 41.3 | — | — | — | — | — | — | — | — | 24.3 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 4.6 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Others | — | 2.1 | — | 2.3 | — | 0.7 | — | 1.4 | — | — | 0.6 | 3.3 | 0.5 | — | — | — | — | 1.4 | — | 5.7 | — | 0.1 | — | — | — | — | — | 2.2 | — | — | 1.3 | 0.1 | — | — | 1.1 | — | — | — | 0.7 | 9.5 | — | — | 0.2 | 2.0 | 1.0 | — | 0.8 | 0.2 | 1.9 | — | — |
| Benzenoids | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Acetophenone | 1.9 | — | — | — | — | — | — | — | 1.6 | — | — | — | — | 1.7 | — | — | 0.3 | — | 0.4 | — | — | 0.1 | 0.9 | 0.7 | — | — | — | 4.1 | — | — | 1.2 | — | 0.6 | — | — | — | — | — | 1.2 | — | 3.7 | — | — | — | 0.4 | 0.6 | 1.5 | 0.1 | — | 33.2 | 6.8 |
| Benzyl acetate | — | — | — | — | — | — | — | — | — | 0.3 | — | — | — | — | — | 7.1 | 0.3 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1.2 | — | 2.3 | — | — | — | — | — | — |
| Benzaldehyde | 1.8 | — | — | — | — | — | — | — | 0.7 | 3.9 | — | 1.5 | — | 4.3 | 0.5 | 2.8 | 0.3 | 0.8 | 5.0 | — | — | 4.0 | 0.1 | 0.6 | — | — | — | 1.4 | 0.5 | 10.3 | 6.7 | 1.1 | 23.3 | — | — | 8.7 | — | 1.7 | 0.5 | — | 0.9 | 2.5 | 1.9 | — | 1.4 | — | 6.1 | 0.2 | — | 1.4 | 0.9 |
| Benzyl alcohol | 15.8 | 1.8 | — | — | — | — | — | — | — | 2.3 | — | 7.5 | — | — | 2.7 | — | 22.6 | 8.3 | 0.4 | — | — | 1.0 | — | — | — | — | — | — | — | — | 12.5 | 1.9 | 11.3 | — | 2.3 | 1.1 | — | — | — | — | — | 0.3 | 20.3 | — | 11.7 | — | 7.2 | 4.3 | — | 5.6 | — |
| 1,2-Dimethoxybenzene | — | — | — | — | — | — | — | — | — | — | — | — | 0.5 | — | — | — | — | — | 0.3 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| 1,4-Dimethoxybenzene | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0.5 | 7.0 | — | 1.7 | 0.5 | — | — | — | — | 2.3 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0.8 | — | — | — | — | — | — | — |
| 3,5-Dimethoxybenzoate | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 2.2 | — | — | 3.7 | — | 2.4 | — | — | — | — | 0.7 | — | — | — | — | — | — | — | — | — | — | — | — | 1.7 | — | — | — | — | — | 3.9 | — | — | — |
| 3,5-Dimethoxytoluene | — | — | — | — | — | — | — | 93.6 | — | — | — | — | 1.5 | — | — | 38.3 | 19.4 | — | 21.4 | — | 91.5 | 57.6 | 0.1 | 36.9 | — | — | — | — | 38.5 | — | — | — | 0.3 | 0.6 | — | — | — | — | — | 19.8 | — | 29.2 | — | — | 0.3 | — | — | 48.0 | — | — | 0.6 |
| Ethyl benzoate | — | — | — | — | — | — | — | — | — | 1.0 | — | 3.0 | — | — | 0.8 | 2.6 | — | 1.6 | — | — | — | — | — | 0.3 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1.0 | — | 1.0 | — | — | 0.4 | — | — | — | |
| Methyl benzoate | 11.0 | — | — | — | 0.5 | — | — | 1.3 | 0.9 | 16.8 | — | 2.9 | — | — | 3.1 | 1.6 | 2.8 | 11.6 | 9.5 | 4.8 | — | 1.1 | — | 1.0 | 1.3 | — | — | 1.4 | 1.0 | 0.7 | 0.3 | 11.6 | 0.6 | 0.3 | — | 0.8 | 12.5 | — | — | — | — | 1.2 | 9.6 | — | 12.8 | — | 6.9 | 7.7 | — | 5.2 | 6.4 |
| Methyl salicylate | 22.4 | — | — | — | — | — | — | — | — | 8.1 | — | 18.9 | — | — | 14.0 | 11.8 | 16.3 | 33.8 | 21.9 | — | — | 3.2 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 19.7 | — | 36.4 | — | — | 16.3 | — | 40.7 | 42.7 |
| Phenylacetaldehyde | — | — | — | — | — | — | — | — | — | 5.4 | — | — | — | 0.7 | — | — | — | — | 0.3 | — | — | 0.4 | — | — | — | — | — | — | — | 6.7 | 3.0 | 3.0 | 2.0 | — | — | 3.1 | — | — | — | — | — | 0.8 | — | — | — | — | 1.5 | 0.6 | — | — | — |
| 2-Phenylethanol | — | — | 2.8 | — | — | — | — | — | — | 36.7 | — | — | 2.3 | — | — | — | — | — | 1.2 | 2.9 | — | 7.1 | — | — | — | — | — | — | — | 44.6 | 10.2 | 48.6 | 2.6 | — | 17.1 | 1.1 | — | — | — | — | — | 0.8 | — | 1.6 | — | — | 1.9 | — | — | — | — |
| Others | 8.6 | 0.5 | — | — | 0.4 | — | — | — | — | 2.9 | — | 10.1 | 11.3 | — | — | 19.7 | 4.1 | — | 0.3 | — | — | 0.6 | 0.3 | — | — | — | — | 3.5 | — | 0.5 | 2.1 | 10.6 | 0.7 | — | 1.2 | — | — | — | — | 5.4 | — | — | 5.9 | — | 12.9 | — | 2.4 | 5.4 | 1.0 | 12.6 | — |
| Fatty acids derivatives | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Decanal | — | — | — | 12.4 | 38.3 | 1.5 | — | — | 0.9 | — | — | — | 3.2 | — | 3.5 | 1.3 | — | 0.2 | 4.4 | 1.6 | — | 1.7 | — | 2.4 | — | 0.6 | — | — | — | — | — | 0.4 | 7.2 | 0.9 | — | — | — | — | 0.9 | 1.0 | 1.9 | — | 8.7 | 1.7 | 3.9 | — | 0.8 | — | — | — | — |
| 2-Hexenal | — | — | 1.8 | — | — | — | — | — | — | 0.2 | 0.6 | — | — | 12.4 | 7.9 | — | — | 2.9 | 4.0 | 0.0 | — | — | — | 4.5 | — | — | — | — | 8.2 | — | — | — | 2.4 | — | 20.1 | 31.7 | 15.4 | 82.1 | — | 0.5 | 3.0 | — | 1.9 | — | 0.4 | 1.1 | — | 0.8 | 1.7 | — | — |
| cis-3-Hexenol | 21.1 | 4.0 | — | 7.9 | — | 7.7 | — | 0.7 | 0.8 | 4.2 | 2.6 | — | 19.1 | — | 5.3 | 9.6 | — | 5.6 | 1.7 | 4.7 | — | 4.2 | — | 1.5 | 5.0 | — | 10.8 | 16.2 | 2.5 | — | 0.6 | 3.7 | 2.5 | 13.0 | — | 1.2 | 49.4 | — | 11.6 | — | 0.5 | — | 1.8 | 0.8 | — | — | 0.6 | 1.2 | 0.6 | — | — |
| cis-3-Hexenyl acetate | 8.6 | 2.6 | — | — | — | — | 6.1 | — | — | 15.8 | 16.3 | — | 1.3 | — | 28.8 | — | — | 0.2 | 4.0 | — | — | 0.1 | — | — | — | — | — | 1.7 | — | — | — | — | 1.3 | 0.2 | — | — | — | — | 3.4 | — | — | — | 3.3 | — | 1.1 | — | — | — | — | — | — |
| Nonanal | — | — | — | 5.3 | 6.6 | 3.9 | — | — | 0.9 | — | — | 1.1 | — | 1.6 | 1.7 | — | — | — | 0.6 | — | 1.7 | 0.8 | — | 0.5 | — | 0.7 | — | — | — | — | — | — | 0.6 | — | — | 1.1 | — | — | — | — | 1.3 | — | 5.1 | — | — | — | 0.8 | 0.4 | 2.0 | — | 1.8 |
| Octanal | — | — | 1.1 | 9.6 | 27.1 | — | 1.3 | — | — | — | 0.3 | 2.4 | 1.2 | 0.8 | 11.3 | — | — | 0.3 | 2.7 | 4.3 | 2.5 | 2.9 | 0.9 | 6.5 | — | — | — | 2.6 | — | — | 0.4 | 0.7 | 17.0 | 1.6 | 3.4 | 1.0 | — | — | 1.2 | 0.4 | 0.6 | — | 5.6 | — | 0.4 | — | 1.3 | — | — | — | 1.2 |
| Others | 1.8 | 1.9 | 2.2 | 3.3 | 11.1 | 1.4 | 1.2 | 1.2 | — | 1.8 | 5.4 | — | 1.8 | 9.1 | 11.9 | 1.8 | 1.1 | 4.9 | 6.4 | 7.3 | — | 5.4 | 0.6 | 2.9 | 1.2 | — | — | 2.5 | 9.6 | 8.6 | 3.7 | 4.3 | 20.1 | 0.2 | 9.5 | 9.7 | 13.2 | 6.6 | 0.4 | 1.5 | — | — | 9.3 | 2.9 | 8.2 | — | 3.8 | 1.0 | — | — | 1.1 |
| Hydrocarbons | 5.5 | — | 1.4 | — | 4.5 | 0.9 | 1.7 | — | 2.2 | 0.3 | 0.7 | 5.7 | 1.7 | — | 5.3 | — | 0.6 | 0.3 | 2.4 | 2.2 | — | 3.4 | 0.9 | 6.2 | — | 0.6 | — | 11.5 | 0.3 | — | 1.4 | 3.7 | 1.0 | — | — | — | 0.8 | — | 1.7 | — | 10.5 | — | 0.1 | 24.5 | 0.7 | 0.5 | 0.7 | 2.1 | 8.3 | — | 10.1 |
| Others | 1.6 | — | — | — | — | — | — | — | — | 0.1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 31.5 | — | — | — | — | — | — | — | 0.3 | — | 0.4 | — | — | — | — | — | — |
| Type | Compounds | Descriptions* | Threshold values*3 | Odor Classification |
|---|---|---|---|---|
| Monoterpenoids | Eucalyptol | Characteristic camphoraceous odor and fresh, pungent, cooling taste. | 1 to 64 ppb | Herbal |
| d-Limonene | Pleasant, lemon-like odor. | 4 to 229 ppb | Citrus | |
| Linalool | Typical pleasant floral odor. | 4 to 10 ppb | Fruity | |
| trans-β-Ocimene | Warm herbaceous odor. | n/a | Herbal | |
| α-Pinene | Charastristic odor of pine. | 2.5 to 65 ppb | Herbal | |
| α-Terpineol | Characteristic lilac odor with a sweet taste reminiscent of peach on dilution. | 280 to 350 ppb | Herbal | |
| Sesquiterpene | Caryophyllene | Woody-spicy, dry, clove-like aroma. | 64 to 90 ppb | Woody |
| a-Farnesene | Fruity, herbaceous odor. | n/a | Fruity | |
| Geranyl acetone | Green and rosy floral odor. Floral, fruity, fatty, green, pear, apple and banana nuances. | 60 ppb to 6.4 ppm | Fruity | |
| Dihydro-β-ionone | Odor similar to β-ionone with a leather note. | n/a | Fruity | |
| β-Ionone | Woody, berry characteristic violet odor. | 0.007 to 205 ppb | Fruity | |
| Benzenoid | Acetophenone | Characteristic bergamot-lavender odor and persistent sweet, and acid taste. | 170 ppb | Anise |
| Benzaldehyde | Characteristic odor and aromatic taste similar to bitter almond. | 100 ppb to 4.6 ppm | Fruity | |
| Benzyl alcohol | Characteristic pleasant, fruity odor and a slightly pungent, sweet taste. | 1.2 to 1000 ppb | Fruity | |
| 3,5-Dimethoxytoluene | Humid and fresh green note with a little phenolic and spicy character reminiscent of a flower shop *2. | n/a | Spicy | |
| Methyl benzoate | Fruity odor, similar to cananga. | 110 ppb | Fruity | |
| Methyl salicylate | Minty, spicy, sweet, wintergreen-like odor. | 40 ppb | Anise | |
| Phenylacetaldehyde | Sweet, floral honey rosy and slightly powdery odor with a hurmented note at 1.0%. | 4 ppb | Rosy | |
| 2-Phenylethanol | Characteristic rose-like odor and an initially slightly bitter taste. | 0.015 ppb to 3.5 ppm | Rosy | |
| Fatty acid derivatives | Decanal | Penetrating, sweet, waxy, floral, citrus, pronounced fatty odor. | 0.1 to 6 ppb | Citrus |
| 2-Hexenal | Pleasant, green, apple-like odor. | 30 ppb | Green | |
| cis-3-Hexenol | Intense, grassy-green odor. | 70 ppb | Green | |
| cis-3-Hexenyl acetate | Powerful, green, apple-like odor. | n/a | Green | |
| Nonanal | Strong, fatty odor developing an orange and rose note on dilution. | 1 to 8 ppb | Citrus | |
| Octanal | Strong, fatty, orange-like odor. | 1.4 to 6.4 ppb | Citrus |
| Group | Cultivars | Group of scent compounds (%) | Sensual features | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Anise | Citrus | Fruity | Green | Herbal | Rosy | Spicy | Woody | |||
| Anise | Harutenshi | 34 | 3 | 21 | 9 | 15 | — | — | 10 | Weak sweet odor with an anise nuance. |
| Tender Beauty | 20 | 20 | 33 | 7 | 2 | — | — | 1 | Weak sweet odor with an anise nuance. | |
| Upstar | 37 | 4 | 26 | 2 | 1 | — | 0 | 4 | Weak sweet odor with an anise nuance. | |
| Yukitsubo | 74 | — | 12 | — | — | — | — | 1 | Weak sweet odor with an anise nuance. | |
| Yumenomurasaki | 50 | 6 | 7 | — | 18 | — | 1 | 5 | Faint sweet odor with an anice nuance. | |
| Citrus | Apricot Beauty | — | 14 | 34 | 7 | 15 | — | — | 1 | Fresh sweet odor with a citrus note. |
| Barbados | — | 1 | 17 | 2 | 60 | 3 | — | 6 | Weak sweet odor with a citrus note. | |
| Bellona | — | 72 | 3 | — | 1 | — | — | 7 | Fresh citrus odor like an orange. | |
| Beniyutaka | — | 7 | 19 | 8 | 50 | — | — | — | Fresh citrus odor like a Japanese pepper. | |
| Golden Apeldoorn | 2 | 21 | 19 | 12 | 28 | 1 | — | 2 | Light jucy odor with a citrus note. | |
| Lady Margot | — | 10 | 34 | 5 | 45 | — | — | — | Cool and sweet odor. | |
| Fruity | Ballerina | — | 27 | 56 | 8 | 1 | — | — | — | Fruity sweet odor. |
| Benizukin | — | 2 | 78 | 6 | 5 | — | — | — | Fresh and juicy odor. | |
| Desire | — | 0 | 54 | 20 | 0 | — | — | 1 | Warm fruity odor. | |
| General de Wet | — | 6 | 39 | 20 | 12 | 2 | 2 | 1 | Fruity odor with an apple nuance. | |
| Koki | 1 | 12 | 21 | 6 | 4 | — | 37 | 1 | Fresh and fruity odor. | |
| Murasakizuisho | 1 | 29 | 35 | 6 | — | 5 | 0 | 2 | Weak fruity odor like an almond cake. | |
| Green | Angelique | 24 | — | 29 | 30 | — | — | — | — | Weak sweet odor with a green note. |
| Goromaru | 14 | 16 | 6 | 42 | 1 | — | — | — | Green odor like an apple. | |
| Orange Princess | — | 7 | 7 | 20 | 4 | 17 | — | 1 | Unpleasant sweet odor with a green note. | |
| Orange Queen | — | 15 | 19 | 33 | 10 | 4 | — | — | Week green odor with a citrus note. | |
| Pink Diamond | — | — | 16 | 65 | 4 | — | — | 2 | Faint green odor. | |
| Pretty Woman | — | — | 2 | 82 | 10 | — | — | — | Faint green odor. | |
| Herbal | Carnival de Rio | 2 | 2 | 2 | 1 | 91 | — | — | — | Fweet resin-like odor. |
| Finola | 19 | 4 | 12 | — | 40 | — | — | 1 | Weak resin-like odor. | |
| Koiakane | 1 | 1 | 3 | — | 69 | — | 0 | — | Resin-like odor. | |
| Largo | — | 21 | — | — | 75 | — | — | — | Fresh and sweet odor with a resin nuance. | |
| Leen van der Mark | — | — | — | 11 | 84 | — | — | — | Faint resin-like odor with a green note. | |
| Magier | 4 | 16 | 3 | 18 | 32 | — | — | — | Weak cool odor with a green note. | |
| Orange Bouquet | — | 3 | 1 | 13 | 77 | — | 1 | 1 | Weak sweet odor with a green note. | |
| Prince of Nippon | 1 | 20 | 1 | 15 | 57 | — | — | 2 | Weak fresh and cool odor. | |
| Shirayukihime | 4 | 4 | 29 | 3 | 45 | — | — | — | Weak resin-lke odor with a citrus note. | |
| Usugesho | 1 | — | 3 | 1 | 83 | — | — | — | Weak resin-lke odor with a citrus note. | |
| Wisteria Maid | — | 5 | 43 | 2 | 33 | — | — | 1 | Light sweet odor with a resin-like note. | |
| Herbal-honey | Monsella | — | 8 | 11 | — | 17 | 51 | — | 4 | Fresh and cool odor with a honey note. |
| Monte Carlo | 1 | 10 | 20 | 1 | 43 | 13 | — | 1 | Fresh and cool odor with a honey note. | |
| Viking | 2 | 18 | 27 | 1 | 39 | 3 | — | 0 | Fresh and cool odor with a weak honey note. | |
| Rosy | Diana | 8 | — | 23 | 20 | 0 | 42 | — | — | Rosy odor with a green note. |
| Montreux | — | 1 | 17 | 4 | 0 | 52 | — | 7 | Rosy odor. | |
| Spicy | Capri | — | — | 1 | 1 | — | — | 94 | 2 | Spicy and medicinal odor. |
| Harunoawayuki | 12 | 8 | 4 | 10 | — | — | 38 | — | Weak sweet odor with a medicinal note. | |
| Harunohimatsuri | 17 | 1 | 26 | — | 28 | — | 19 | — | Weak sweet odor with a medicinal note. | |
| Hatsuzakura | 22 | 8 | 19 | 10 | 6 | 2 | 21 | — | Weak sweet odor with a medicinal note. | |
| Jan van Nes | — | 4 | — | — | 1 | — | 91 | 4 | Spicy and medicinal odor. | |
| Kikomachi | 3 | 5 | 6 | 4 | — | 8 | 58 | 0 | Sweet spicy odor with a medicinal nuance. | |
| Merry Widow | — | — | 2 | 11 | 36 | — | 38 | 0 | Fresh and medicinal odor. | |
| Sakura | — | 2 | 3 | 0 | 45 | — | 20 | 4 | Faint sweet odor with a resin nuance. | |
| Strong Gold | — | — | 10 | — | 49 | 2 | 29 | — | Spicy and medicinal odor. | |
| Wedding veil | 16 | 5 | 12 | 1 | 1 | 1 | 48 | 1 | Weak sweet odor with a medicinal note. | |
| Woody | Ile de France | — | 9 | 10 | 5 | 6 | 3 | — | 26 | Faint woody odor. |
| Tonami City | — | 2 | 45 | 1 | — | 2 | — | 20 | Light sweet odor with a woody nuance. | |
Comparison of types and amounts of floral scent compounds absorbed on Twisters by tulip cultivars.
Group 1 had an aromatic, spicy, and sweet odor similar to western-style sweets and the odor was derived mainly from methyl salicylate. In addition, the odors of ‘Yukitsubo’, which had a high percentage of acetophenone, and ‘Tender Beauty’, which contained high levels of benzyl alcohol, smelled sweeter than others. The content of emitted scent compounds of ‘Yumenomurasaki’ was low and its scent strength was low.
2. Group 2, citrusGroup 2 had a fresh and sweet odor like oranges and comprised 5 cultivars that had a high percentage of monoterpenes and ‘Bellona’, which had a high percentage of fatty acid derivatives. The former cultivars had a fresh, juicy, and sweet citrus odor derived from eucalyptol or trans-β-ocimene in addition to linalool. ‘Beniyutaka’, which contained 2-hexanal in addition to high levels of linalool and trans-β-ocimene, had an especially fresh citrus odor with a green note like a Japanese pepper. ‘Bellona’, which contained high levels of decanal and octanal, had an oily and sweet odor like orange peel.
3. Group 3, fruityGroup 3 had a fruity odor like berries and apples and the odor quality was divided into 4 types. ‘Benizukin’, which contained α-farnesene and geranylacetone, had a fresh and juicy fruit odor. ‘Ballerina’ and ‘General de Wet’, which contained a high level of β-ionone, had a fruity odor that was derived from β-ionone and decanal. The odor strengths of these cultivars were stronger than the cultivars with a high amount of scent compounds, such as ‘Koiakane’, although of the overall amount of scent compounds in these cultivars was relatively low. It is considered that β-ionone, the major scent compound of ‘Ballerina’ and ‘General de Wet’, has a low olfactory threshold. ‘Desire’ had a sweet odor derived from linalool. The major scent compound of ‘Koki’ was 3,5-dimethoxytoluene, but the odor was a fresh and juicy odor that was derived from linalool. This is likely due to the difference of the olfactory threshold between linalool and 3,5-dimethoxytoluene. ‘Murasakizuisho’ had a weak and sweet odor, similar to bitter almond, derived from benzaldehyde.
4. Group 4, greenMany tulip cultivars have a weak green odor. All floral scents of 6 cultivars of group 5 contained fatty acid derivatives that had a green odor. Most of them had a grass-like weak odor, but ‘Goromaru’, which contained a high level of cis-3-hexenyl acetate, which has a green apple-like odor, had a green apple-like odor.
5. Group 5, herbalMany cultivars of tulip have herbal odors distinct from the grassy odor group. Eight cultivars in group 6 had trans-β-ocimene as the major scent compound (ocimene-type) and 3 cultivars had eucalyptol, d-limonene, and α-pinene as the major scent compounds. Ocimene-type cultivars had an oily, not sweet and herbaceous odor. ‘Koiakane’ had a relatively high level of scent compounds (Table 2), but its floral scent was not strong because trans-β-ocimene has a warm herbaceous odor and is not very sweet. The three cultivars that contained eucalyptol had a cool and herbal scent.
6. Group 6, herbal-honeyGroup 7, ‘Monte Carlo’ and its sports, ‘Monsella’ and ‘Viking’, had a herbal odor with a honey note. These cultivars contained 2-phenylethanol and phenylacetaldehyde, which had a rosy honey odor in addition to eucalyptol.
7. Group 7, RosyTwo cultivars of group 3 had light and rosy scents. They contained higher levels of 2-phenylethanol than other cultivars and their odor originated from this compound.
8. Group 8, spicyThe cultivars of group 8 contained 3,5-dimethoxytoluene (DMT) that had a humid, medicinal and spicy odor. ‘Capri’ and ‘Jan van Nes’, in which DMT was the predominant scent compound, had a humid medicinal odor. ‘Kikomchi’ had a characteristic sweet odor–and contained the highest level of scent compounds among the evaluated cultivars (Fig. 2). Infact, the odor strength of ‘Kikomachi’ was sensed most strongly. ‘Harunohimatsuri’, ‘Merry Widow’, ‘Sakura’, and ‘Strong Gold’ emitted a high level of trans-β-ocimene in addition to DMT. They had an herbal odor soon after flowering, but with time a medicinal spicy odor derived from DMT became more noticeable. ‘Harunoawayuki’, ‘Hatsuzakura’, and ‘Wedding Veil’ contained a high level of methyl salicylate in addition to DMT and had a weak sweet odor with a medicinal note.
9. Group 9, woodyThe cultivars of group 9 had a faint woody odor derived from caryophyllene. The levels of their scent compounds were low relative to other cultivars (Fig. 2).
In this study, we classified the tulip cultivars into 9 groups according to their floral scent composition and the sensual features of a living flower. Roses were the first flowers to be classified based on their scent compounds (Yomogida, 1992), and their classification led to the breeding of modern roses for fragrance and contributed to the appeal of rose scent in flower markets. Similarly, our results may encourage additional efforts to breed fragrant tulips, which will increase their market value.
In addition, our study showed that DMT was one of the major scent compounds in the flowers of tulip cultivars. DMT is a major scent compound in Hybrid Tea roses and is used in the perfume industry as a “relaxing fragrance” (Okazaki et al., 2001). We anticipate that our findings may generate additional value from tulips by, for example, marketing the relaxing effect of tulip cut flowers and the use of tulip petal extracts, although it is necessary to verify the relaxing effect of the floral scent of tulip by DMT. Future work will be aimed at the derivation of floral scents among tulip cultivars and the analysis of scent compounds in wild tulip species.
