Unit 2

Question 1

Essential oils

Answer 1

• aromatic, volatile substances extracted from a single botanical source by distillation or expression
• found in leaves, flowers, seeds, plant stems, twigs, tree, bark, resin, fruit pulp and peel

Question 2

8 characteristics of essential oils

Answer 2

1) aromatic
2) volatile
3) very powerful
4) flammable
5) soluble in oil
6) liquid
7) non greasy
8) expensive

Question 3

Steam/water distillation

Answer 3

• most common method of extraction
• plant material is placed in first part of a still
• it is either mixed with water which is then heated to produce steam or steam under pressure is passed through the plant material
• heat causes essential oil in plant to break down and evaporate
• the mix of steam and oil vapor passes into a cooled pipe and condenses
• liquid passes into a collecting vessel where the oil and water separate making it easier to decant the oil

Question 4

7 methods of extraction

Answer 4

• steam/water distillation
• expression
• solvent extraction
• carbon dioxide extraction
• hydro diffusion
• enfleurage
• maceration

Question 5

Hydro diffusion

Answer 5

• similar to distillation expect it percolates down through the plant material instead of up
• when cooled at the bottom of the tank, the oil either floats or sinks
• advantage is that it is faster than distillation which results in less damage to the oil due to shorter period of time

Question 6

Expression

Answer 6

• oils of citrus fruits are contained in tiny sacs in the peel
• oils are extracted by pressure
• the fruits pulp and pith are removed and peel is squeezed to release its oil
• used to be done by hand

Question 7

Solvent extraction

Answer 7

• method used when the aromatic essence is difficult to obtain by distillation
• might damage the delicate fragrance of plant

Question 8

Resinoid (benzoin, myrhh)

Answer 8

• when the bark of a tree or a bush is cut it seems to bleed

Question 9

Concrete

Answer 9

• when a plants essential oil is damaged by hot water or steam

Question 10

Absolutes (rose, jasmine)

Answer 10

• after extraction concretes are usually treated further to obtain what is known as the above
• a liquid which is thicker and more concentrated than a pure essential oil
• used in small amounts

Question 11

Enfleurage

Answer 11

• old extraction process that produces a waxy substance similar to concrete known as pomade
• labour intensive therefore expensive
• only works with flowers which carry on producing essential oils after they have been harvested

Question 12

Adulteration

Answer 12

• changing an expensive pure oil to make it go further and in some cases make more money

Question 13

Methods of testing oil quality

Answer 13

• sensory testing
• gas chromatography
• Infa red
• optical rotation

Question 14

What causes spoilage of essential oils

Answer 14

• extended storage periods
• incorrect storage in light, heat and air
• causes oil to chemically break down and alter the effects through processes such as oxidation or hydrolysis
• changes can also make oil hazardous

Question 15

Quickest oil to degrade

Answer 15

• cold pressed citrus oils

Question 16

Shelf life

Answer 16

• 2 years
• rose absolute can improve with age and last up to 5 years

Question 17

Synergy

Answer 17

• to work together
• when 2 or more oils work together they produce more of an effect than they do alone

Question 18

Other factors affecting the quality of oils

Answer 18

• soil quality
• rainfall
• temp
• climate
• altitude
• location
• methods of harvesting
• part of plant used
• method of extraction
• storage conditions
• any adulteration