alpha-vetivone, beta-vetivone, and khusimol
Vetiver
Vetiveria zizanioides (Poaceae)
Vetiver oil is steam distilled from the aromatic roots of the tropical
grass Vetiveria zizanioides, a robust grass as tall as a man
and a native to the Indian subcontinent. Vetiver oil has a long history
of use. Today, the main producers are Indonesia, Haiti and Reunion, but
the grass is cultivated in many tropical and subtropical countries. The
photo in the middle shows the roots ready for distillation. Vetiver oil
is a viscous amber-coloured oil with a characteristic rooty-green, precious-woody
odour of great tenacity.
Vetiver oil is dominated by a complex mixture of oxygenated sesquiterpenes.
The ketones alpha-vetivone (compare with nootkatone from grapefruit)
and beta-vetivone, which usually form more than 10 % of the oil, as well
as khusimol, ca. 15 %, and its derivatives, contribute significantly to
its odour [6].
Vetiver oil is used in luxury perfumes for persistent green-woody notes.
An even finer product, called vetiveryl acetate, is created by acetylating
the sesquiterpene alcohols present in the oil. It has an elegant, soft,
fruity-woody character. In classical perfumery, the oils of vetiver, patchouli
and sandalwood in
combination with a jasmine
and gardenia
complex was the base of the famous Crêpe de Chine note [3]. Vetiver
products are used in many modern men's colognes, e.g Vetiver (Guerlain
1959), and the newer Hugo Dark Blue (Boss 1999) and Azzura (Azzaro 1999).
Lately, vetiver grass has gained focus for quite another reason. Its very
excessive roots are effective in preventing soil erosion in the tropics
where the original forest has been destroyed.
Vetiver oil is also called vetivert, khus-khus, khas-khas or 'oil of tranquillity'
in India.
alpha-ionone and alpha-dihydro-ionone
3(Z)-hexen-1-ol and 2(E),6(Z)-nonadien-1-ol
Violet
Viola odorata (Violaceae) Sweet violet
Sweet violet is a native of the Mediterranean countries and Asia Minor.
From old ages it has been grown in gardens, and now it has spread to most
of Europe. It is flowering in early spring before foliation of the trees,
and it may form dense stands on the edges of forests, on slopes in parks,
etc., making itself known with the enchanting scent of the flowers.
In the vicinity of Hyères in southern France, cultured varieties
of V. odorata, called Parma violets and Victoria violets, have
been grown, not because of the flowers, but for the sake of their green
leaves. From these the expensive violet leaf oil is obtained (around 0.1
%), with an odour character completely different from that of the flowers.
The unique, fine, sweet fragrance of the violet flowers is dominated by
ionones (22 %), e.g. alpha-ionone and alpha-dihydroionone. Violet leaf
oil, on the contrary, is dominated by a number of secondary metabolites
from linolic- and linolenic acid, e.g. 3(Z)-hexen-1-ol, called leaf alcohol
(it has a very powerful odour like fresh cut grass), and 2(E),6(Z)-nonadienol,
called violet leaf alcohol (it has a very powerful cucumber-like
odour). Violet leaf oil has a sparklingly intense 'green' odour, being
much appreciated in fine perfumery [3].
The famous perfume Vera Violetta (Roger & Gallet 1892) showed the
first creative combination of natural violet leaf oil with synthetically
made alpha- and beta-ionone.
Etymology: Gr. ion, violet.
The perfumery-chemist Paul Bedoukian discovered in the 1960s during experiments with acetals of alkynals that 2-nonynal dimethyl acetal has a powerful odour resembling that of violet leaf oil. This compound is marketed by Bedoukian Research Inc. under the name of Parmavert ®.
2-nonynal dimethyl acetal, Parmavert ®
pentanal, 1-penten-3-ol and 1-ethyl-3-methyl-benzene from walnut flavor, and 5-hydroxy-1,4-naphthoquinone (juglone) from walnut husk
Juglans regia (Juglandaceae) Persian Walnut, Common Walnut
The walnut genus has about 20 species. Common walnut is a native of the region from Greece and the Balkan peninsula throughout southwest and central Asia and the Himalayas to southwest China. In Kyrgyzstan there are large walnut forests. The beautiful trees carry male flowers in drooping catkins, and female flowers in terminal clusters of two to five. The ripe fruit has a green, semi-fleshy husk around a hard, grooved shell surrounding the deeply folded seed. The related Pecan Nut, Carya illinoensis (Juglandaceae), is more oblong and has a smooth shell.
Walnuts are eaten as a delicacy all over the world, especially in salads (e.g. Waldorf salad), deserts and confectionery. They contain more than 50 % lipids with a high percentage of polyunsaturated fatty acids. It is well established that consumption of walnuts has benefits to health. For example, walnuts are high in omega-3-fatty acids and contain powerful antioxidants [138][139][140].
The high degree of unsaturation has an impact on the shelf-life of walnuts compared with other nuts, and is
behind the mild but characteristic walnut flavour (mostly perceived retronasally during eating). Tannins in the pellicle are responsible for the astringent taste as well as the brown color.
Elmore et al. analysed the headspace aroma compounds of walnuts from various locations and found that they were mainly lipid-derived aldehydes and alcohols, in particular hexanal, pentanal, 1-hexanol and 1-pentanol from linoleic acid breakdown, and 1-penten-3-ol from alpha-linolenic acid breakdown. Moreover, alkylbenzenes of molecular weight 120, in particular 1-ethyl-3-methylbenzene, were present. The proportions of these volatiles depended on the origin of the nuts [141].
Etymology: Germanic wal, foreign; Lat. jovis glans or juglans, Jupiter's nut; Lat. regia, royal.
P.S. Walnut leaves and husks contain a glycoside hydrolysing to a yellow compound called juglone, which is chemically 5-hydroxy-1,4-naphthoquinone. It is an allelopathic compound affecting the growth of other plants. Landscapers have long known that gardening underneath or near walnut trees can be difficult! Juglone finds use as a coloring agent in foods and cosmetics. It is also called Nucin.