Methods Of Extraction

Question 1

EXPRESSION

Answer 1

Cold, mechanical process used for citrus oils as near surface of peel.
Involves squeezing & rasping.

Question 2

DISTILLATION

Answer 2

Hot process using water, steam or both together.

• plant material heated with water/steam
• steam produced condenses on cold surface & run off collected
• EO floats on surface and separated off
• water left is hydrosol/floral water.

Increasing pressure reduces temperature needed = less harm to EO

Question 3

DISTILLATION - COHABATION

Answer 3

Used in Rose EO (not absolute) - where distillate water is put back into distillation pot and re-distilled.

• Used to recover as much as possible of hydrophyllic components eg phenyl ethyl alcohol in roses (rose scent). EO from 2nd distillation contains 60% more of above.
• Both EOs from distillations are added together.

Question 4

DISTILLATION - FRACTIONAL

Answer 4

Used in Ylang Ylang EO production = YY extra, 1st, 2nd, 3rd grades.

Distillation stopped & started to allow distillate to be collected in batches or fractions.
Usually timed & separated by specific gravity measurements

Question 5

DISTILLATION - RECTIFICATION

Answer 5

Distillation used as a secondary/further process to purify - remove more of chemical constituents not wanted, eg safrole, bergapten or impurities

Question 6

AROMATIC EXTRACTIONS

Answer 6

Use solvents rather than water/steam & produce an absolute not an EO. Not organic as trace solvents left.
Used for fragile plant matter - eg Rose or Jasmine blossoms.
2 stage process:
1 - plant steeped in solvent (hexane) then distilled - leaves a sticky substance - a ‘Concrete’ if flowers, leaves, stems or a ‘Resinoid’ if dry plants eg roots.
2 - Dissolved in alcohol & chilled - precipitates unwanted matter - filtered. Alcohol removed by vacuum distillation (reduces temp) = leaves the absolute.

Question 7

CO2 EXTRACTION

Answer 7

• Uses CO2 as solvent as can reach hypercritical state (neither liquid or gas but properties of both).
• CO2 warmed & pressurised till hypercritical state reached - disperses like gas but excellent solvent properties.
• Added to plant material - extraction v. quick
• Filter to remove solid plant material
• Pressure & temperature reduced - CO2 returns to gas & evaporates from oil - leaving a pure EO.

Benefits - CO2 is inert - no chemical reaction w/ EO & no organic solvents so no residue in EO
But - expensive due to kit required to reach 200 atmospheres!

Question 8

ENFLEURAGE

Answer 8

• Blossoms laid on thin layer of fat spread on glass
• fat absorbs lipophylic components from flowers
• Keep replacing blossoms w/ fresh until fat is saturated w/ EOs = pomade
• can be used as is or processed to an absolute.
  
  • fat washed w/ hexane - dissolves EO, not fat
  • Ethanol used to wash product out of hexane
  • Ethanol evaporated to leave an absolute