Volatile/ Essential Oils

Question 1

What are volatile oils

Answer 1

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.

Question 2

What are the characteristics of volatile oils

Answer 2

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.

Question 3

What are the three classes of volatile oils based on origin

Answer 3

• 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

Question 4

All official volatile oils are of vegetable origin.

True/false

Answer 4

True

Question 5

What part in a plant is volatile oils stored

Answer 5

-Oil cell
–Glandular trichomes
–Secretory cavities
–Secretory canals

Question 6

What part in animals is volatile oils stored

Answer 6

For animals in odorous sacs

Question 7

How are mustard and almond volatile oils produced

Answer 7

the enzymatic hydrolysis of their glycosides

Eg. Almond: Amygdalin (cyanogenetic glycoside)
emulsin (enzyme)

glucose + benzaldehyde + HCN

Question 8

Uses of volatile oils

Answer 8

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

Question 9

Medicinal uses of volatile oils

Answer 9

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.

Question 10

What does the chemical composition of VO depend on

Answer 10

origin, climatic conditions, and plant species.

Question 11

What are the constituents of the individual VO it may have

Answer 11

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.

Question 12

The odour and taste is mainly determined by … ?

Answer 12

The Oxygenated constituents

Question 13

The absence of even one component may change the aroma of VO

TRUE/FALSE

Answer 13

True

Every member of the mixture is essential to the odor and flavor.

Question 14

Are the oxygenated constituents soluble in water and alcohol and which solvent is it more soluble in?

Answer 14

The oxygenated constituents are to some extent soluble in water but more soluble in alcohol.

Question 15

What are the two biochemical pathways involving different enzymatic reactions of the biosynthesis of VO

Answer 15

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

Question 16

Physical properties of Essential oils

Answer 16

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

Question 17

The plant material is boiled with water and the vapour is passed through a condenser, collected and the oil separated from the water.

Answer 17

Water distillation

Question 18

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.

Answer 18

Steam distillation

Question 19

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)

Answer 19

Enfleurage

Question 20

warm air passed through the flower and then through a spray of melted fat

Answer 20

Pneumatic method

Question 21

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.

Answer 21

Digestion method

Question 22

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

Answer 22

Scarification (ecuelle a piquer )

Question 23

The material eg rind of citrus, is soaked in warm water and pressed in a clothing material.

Answer 23

Expression( cold pressing)

Question 24

oil is extracted with organic solvent eg ethanol and the oil separated by distillation.

Answer 24

Extraction with solvents

Question 25

How is Enzymatic hydrolysis (for glycosidic volatile oils e.g. mustard oil) done

Answer 25

Amygdaline(glycoside)/water/emulsin(enzyme) = glucose+ cyanide + volatile oil (benzaldehyde)

Question 26

What are the 6 chemical transformation processes in VO

Answer 26

* Oxidation * degradation * polymerization * isomerization, * cyclization, or * dehydrogenation

Question 27

What are the effects of chemical transformation of VO

Answer 27

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.

Question 28

What are the four factors which affect stability of VO

Answer 28

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

Question 29

It is natural or synthetic organic compound which may be non-crystalline or viscous liquid substance.

Answer 29

Resin

Question 30

What are the 4 physical properties of resins

Answer 30

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.

Question 31

What is the chemical composition of resins

Answer 31

Chemically, resins are complex mixtures of resin acids, resin alcohols (resinols), resin phenols (resinotannols), esters and chemically inert compounds known as resenes.

Question 32

How may resins be grouped

Answer 32

Oleoresins associate with volatile oils –gum-resins associate with gums –oleo-gum-resins associate with oil and gum •Glycosidic resins occur as glycosides

Question 33

What are the 3 ways resins can be classified

Answer 33

1. Taxonomical classification, i.e. according to botanical origin, e.g. Berberidaceae resins. 2. Classification according to predominating chemical constituent; e.g. acid resins, resene resins, glycosidal resins; etc. 3. Resins may be classified according to the associating component e.g. resins, oleoresins, oleogumresins, balsams.

Question 34

Examples of resins

Answer 34

Resins: colophony, cannabis. •Oleoresins: copaiba, ginger. •Oleo-gum-resins: asafoetida, myrrh. •Balsams: balsam of Tolu, balsam of Peru.

Question 35

aromatic resinous substance with medicinal properties | •They contain cinnamic, benzoic acids, or/and their derivatives

Answer 35

Balsams

Question 36

What does a true balsam contain

Answer 36

Benzoins, Liquid Storaque and the Balsams of Tolu and Peru.

Question 37

aromatic exudates, such as Copaiba Oil and Canada Balsam, are wrongly called balsam. Because?

Answer 37

These are more or less essential oils, resins and oleoresins.

Question 38

Uses of balsam

Answer 38

For their therapeutic and healing properties •in the perfume industry as fixatives •in the cosmetics industry and in cookery as preservatives and aromatizers.

Question 39

Which VO are more dense in water

Answer 39

sassafras, clove, or cinnamon oils