Volatile/ Essential Oils Flashcards
What are volatile oils
are odoriferous substances (usually liquid).
•are of plants and sometimes animal origin (civet and musk deer oil)
•vaporize when exposed at ordinary temperature.
Are also referred to as ethereal or essential oil.
What are the characteristics of volatile oils
They are liquids
•made of complex mixtures of odoriferous principles/compounds
•They are volatile at ordinary temperature and easily evaporate when exposed to air.
•they give a temporary translucent strain when smeared on paper
- Are of vegetables or plants origin
- Frequently associated with other substances such as gums and resins
- They tend to resinify on exposure to high temperature, light and oxygen
- They differ entirely in both chemical and physical properties from fixed oils.
What are the three classes of volatile oils based on origin
- Natural oils: are obtained from plant and are not modified physically or chemically afterwards.
- Artificial oils: are obtained using processes of enriching the essence with one or several of its components.
- Synthetic oils: are usually produced through synthesis of the components. Eg vanilla, lemon and strawberry essences used as fragrance and taste enhancers
All official volatile oils are of vegetable origin.
True/false
True
What part in a plant is volatile oils stored
-Oil cell
–Glandular trichomes
–Secretory cavities
–Secretory canals
What part in animals is volatile oils stored
For animals in odorous sacs
How are mustard and almond volatile oils produced
the enzymatic hydrolysis of their glycosides
Eg. Almond: Amygdalin (cyanogenetic glycoside)
emulsin (enzyme)
glucose + benzaldehyde + HCN
Uses of volatile oils
As Flavoring agents (e.g. oil of lemon)
Industrial deodorants
As carminatives
–e.g. peppermint oil
as starting materials for the synthesis of other compounds (e.g. oil of turpentine).
As counterirritants
•As antioxidants
•In aromatherapy
Insecticides- Limonine and menthol
Medicinal uses of volatile oils
Anti-septic and preservative
➢High phenol content
•as gargles and mouthwashes
eg thymol oil
•Anti-spasmodic
–Eg. Ginger, Lemon balm, Rosemary, Peppermint, Caraway oils
•Anti-bronchitis and Mucolytic.
–Administered as inhalants (e.g. eucalyptus oil)
•As anthelminthic or worm-expellers/killers.
What does the chemical composition of VO depend on
origin, climatic conditions, and plant species.
What are the constituents of the individual VO it may have
may be
•of terpene (made of isoprene units) or aromatic origin
•cyclic or aliphatic in structure
•Hydrocarbon (isoprenes), oxygenated hydrocarbon or in few cases heterocycle.
The odour and taste is mainly determined by … ?
The Oxygenated constituents
The absence of even one component may change the aroma of VO
TRUE/FALSE
True
Every member of the mixture is essential to the odor and flavor.
Are the oxygenated constituents soluble in water and alcohol and which solvent is it more soluble in?
The oxygenated constituents are to some extent soluble in water but more soluble in alcohol.
What are the two biochemical pathways involving different enzymatic reactions of the biosynthesis of VO
Terpene derivatives (terpenoids) formed via the acetate-mevalonic acid pathway and derived from isoprene units (C5) bonded in a chain. •Aromatic compounds formed via the shikimic acid-phenylpropanoid route
Physical properties of Essential oils
They possess characteristic odours.
2.Essential oils are liquid and volatile at room temperature.
3.They have high refractive indices.
4.Most of them are optically active.
5.less dense than water (exceptions is sassafras, clove, or cinnamon oils).
6.are immiscible with water, but sufficiently soluble to impart their odour to water.
–The so called aromatic waters are dependent on this slight solubility.
7.They are soluble in alcohol and dissolve in alcohol to produce tincture
The plant material is boiled with water and the vapour is passed through a condenser, collected and the oil separated from the water.
Water distillation
The plants are placed on a perforated base or sieve and steam generated elsewhere is passed through it. The volatile component volatilise and escape with the water vapour, passed through a condenser, collected and the oil separated from the water.
Steam distillation
Flower petals containing the oils are spread over a thin film of fat placed on a glass plate. The essence passes into the fat until saturated. The oil saturated fat may be used as a pomade or the essential oil may be extracted using 70% alcohol. (extraction of oils used in perfumery)
Enfleurage
warm air passed through the flower and then through a spray of melted fat
Pneumatic method
flower gently heated in melted fat until exhausted, strain and cool the oil laden fat. oil may be extracted with alcohol and sold as flower perfume or oil recovered in the pure form.
Digestion method
used to extract oil from orange fruits. The fruit is place in a specially designed bowl with spikes. The organ is then rotated/tossed in the bowl. The oil cells are punctured by the spikes thereby discharging the oil
Scarification (ecuelle a piquer )
The material eg rind of citrus, is soaked in warm water and pressed in a clothing material.
Expression( cold pressing)
oil is extracted with organic solvent eg ethanol and the oil separated by distillation.
Extraction with solvents
How is Enzymatic hydrolysis (for glycosidic volatile oils e.g. mustard oil) done
Amygdaline(glycoside)/water/emulsin(enzyme)
= glucose+ cyanide + volatile oil (benzaldehyde)
What are the 6 chemical transformation processes in VO
- Oxidation
- degradation
- polymerization
- isomerization,
- cyclization, or
- dehydrogenation
What are the effects of chemical transformation of VO
Organoleptic and viscosity changes:
–development of unpleasant and pungent flavours,
–changes in colour of oils or
–changes in consistency due to resinification
- Also changes in composition
- Degraded oils may sensitize the skin leading to a hypersensitivity reaction or allergic contact dermatitis.
What are the four factors which affect stability of VO
Light- more light means auto/photo-oxidation which will destroy the oil
Temperature
Oxygen availability. This leads to air-induced oxidation reactions, main causes for spoilage. The reason oils must be closed with no space above it.
Metal contaminants: heavy metals from containers (copper and ferrous ions) promote autoxidation, in particular if peroxides are already present
It is natural or synthetic organic compound which may be non-crystalline or viscous liquid substance.
Resin
What are the 4 physical properties of resins
On heating they soften and finally melt.
•Insoluble in water and petroleum ether
•But soluble in alcohol, chloroform and ether.
•Resins burn with a characteristic, smoky flame.
What is the chemical composition of resins
Chemically, resins are complex mixtures of resin acids, resin alcohols (resinols), resin phenols (resinotannols), esters and chemically inert compounds known as resenes.
How may resins be grouped
Oleoresins associate with volatile oils
–gum-resins associate with gums
–oleo-gum-resins associate with oil and gum
•Glycosidic resins occur as glycosides
What are the 3 ways resins can be classified
- Taxonomical classification, i.e. according to botanical origin, e.g. Berberidaceae resins.
- Classification according to predominating chemical constituent; e.g. acid resins, resene resins, glycosidal resins; etc.
- Resins may be classified according to the associating component e.g. resins, oleoresins, oleogumresins, balsams.
Examples of resins
Resins: colophony, cannabis.
•Oleoresins: copaiba, ginger.
•Oleo-gum-resins: asafoetida, myrrh.
•Balsams: balsam of Tolu, balsam of Peru.
aromatic resinous substance with medicinal properties
•They contain cinnamic, benzoic acids, or/and their derivatives
Balsams
What does a true balsam contain
Benzoins, Liquid Storaque and the Balsams of Tolu and Peru.
aromatic exudates, such as Copaiba Oil and Canada Balsam, are wrongly called balsam. Because?
These are more or less essential oils, resins and oleoresins.
Uses of balsam
For their therapeutic and healing properties
•in the perfume industry as fixatives
•in the cosmetics industry and in cookery as preservatives and aromatizers.
Which VO are more dense in water
sassafras, clove, or cinnamon oils
