valerianol, beta-eudesmol, epi-gamma-eudesmol and elemol
Amyris balsamifera (Rutaceae)
Amyris oil or ' Westindian sandal wood oil' is obtained by steam distillation of the wood from this tree belonging to the rue family. It grows in the Caribbean area and along the Gulf of Mexico. The oil has nothing to do with sandalwood oil, the odour is different and not nearly as attractive, although it is pleasantly woody with a balsamic touch. It is much cheaper than sandalwood oil and is used as a fixative in perfumes.
Amyris oil is rich in sesquiterpene alcohols (over 80 %), e.g. valerianol, eudesmol and elemol [6].
15-pentadecanolide
12-R-(+)- and 12-S-(-)-methyl-13-tridecanolide
Angelica archangelica (A. officinalis) (Umbelliferae)
Angelica is a stout umbellifer, about a meter high, the leaves with much dilated, clasping bases and the umbels being almost spherical. It is an old Nordic domestic plant, beloved as told by its name. In Norway, for example, it grows beautifully in the mountains near ice and melt-water.
The seeds and root of Angelica contain several macrocyclic musks, e.g. 15-pentadecanolide and
12-methyl-13-tridecanolide [37]. If you squeeze a few seeds between your fingers and wait for a moment, the fine fragrance of these macrocyclic lactones will appear. 15-Pentadecanolide is one of the most important musks in perfumery. Today it is made by organic chemical synthesis by the Swiss company Firmenich under the trade name Exaltolide ®. It is widely used as a fixative and a synergist, mostly in low concentration (< 5 %) where its influence is discrete but effective. Natural oil of angelica is used in the liqueur Chartreuse.
In Denmark, Sweden and Norway angelica is also called kvan.
trans-anethole
Pimpinella anisum (Umbelliferae)
Anise, probably a native of Asia Minor, has been cultured since antiquity. It is a slender annual umbellifer with small white flowers (enlarged on the photo). Anise oil is steam distilled from the seeds. It is a colourless or slightly yellow liquid with a powerful odour characteristic of trans-anethole, which is present at a concentration of 87-94 % [146].
Anise oil is a classical ingredient in several types of brandy and liqueur - Anisette, Pernod, Ricard, Ouzo, Arak, Sambuca, etc.
Anise brandy contains fairly high levels of anise oil. When mixed with water it becomes turbid, because the lowered alcohol concentration makes the anise oil insoluble, precipitating as an emulsion. Eventually the oil will coalesce into droplets at the surface.
Anise oil is so often used as a flavour in liquorice sweets that most people will say that anise oil smells of liquorice in spite of the fact that it is the other way about.
Anise oil was formerly produced in many countries, mainly in eastern Europe, but it has now been largely replaced by the less expensive star anise oil, which also contains a high percentage of anethole. See also sweet cicely.
L-asparagine
asparagusic acid as a possible precursor of smelly human urinary metabolites
major odorants from
cooked white asparagus
Asparagus officinalis (Liliaceae) Queen of vegetables
Asparagus is a perennial herb with strongly reduced leaves that are small and pellicle-like. Instead the needle-shaped, finely branching twigs arranged in bunches have completely taken over the task of photosynthesis. Asparagus is growing wild in several subspecies from the European Atlantic coast through the Mediterranean countries to western Siberia. It thrives in sandy soil near coastlines.
Cultured varieties of asparagus have been grown i horticulture since antiquity. The horizontal rhizome produces sturdy, soft and savoury shoots during early summer. They are delicious raw, or they may be briefly cooked. White asparaguses are obtained by hoeing. After cutting the shoots, the rhizomes soon make new ones, but cutting must be stopped by the end of June in order to let the plants recover. Asparagus is legitimately called the queen of vegetables.
Asparagus sap is rich in the amino acid L-asparagine which contributes an umami character. It was the first amino acid to be isolated (as its monohydrate), in 1806 from asparagus - hence its name. Moreover, asparagus contains some free sugar, and the green, slightly pea-like flavour of raw asparagus is partly caused by 2-alkyl-3-methoxy-pyrazines [163]. The characteristic flavour of cooked white asparagus has four dominant odorants: 1,2-dithiacyclo-pentene, vanillin, 2-acetylthiazol and dimethyl sulfide [164].
However, the main reason for including asparagus here is the strange phenomenon sometimes called "asparagusuria". Most people observe a distinct and powerful odour from their urine shortly after having eaten asparagus (fresh or cooked). The effect is noticeable very quickly - from 15-30 minutes after the meal. From the viewpoint of a chemist's nose, organic sulphur compounds might be responsible, and this is indeed the case. Waring et al. found the following strongly odoriferous compounds in asparagus-urine headspace: methanethiol, dimethyl sulfide, dimethyl disulfide and 2,4-dithiapentane [165]. Moreover, S-methyl thioacrylate and S-methyl-3-(methylthio)thiopropionate have been detected in the urine. The nature of the biological precursors are still disputed, but a possible candidate is asparagusic acid (1,2-dithiolane-4-carboxylic acid) present in asparagus in rather high concentration. Understanding of the phenomenon of "asparagusuria" has been complicated by observations indicating that not all people produce the smelly derivates, and that not all people, even if they do, have the same ability to smell them [166].
phenethyl cinnamate
Populus balsamifera (Salicaceae)
Most people nowadays think of washing hair by the word 'balsam'. Botanically, however, a balsam is a resin rich in essential oil. East American balm poplar is found in many parks in northern Europe. Around the time of foliation,
the trees can be smelled at a long distance - a green-balsamic, slightly salicylic and fruity-cinnamic odour. The buds are sticky from a balsam having phenethyl cinnamate (m.p. 67 ºC) as one of its main odoriferous components [6]. The Indians called this balsam 'taccamahacca', and used it for various purposes. It is still used ('Balm of Gilead resin') in a few cosmetic products. See also birch.