Aromatherapy Essential Oil Extraction Methods 2 — Questions and Answers
Question 1: What does 'rectification' mean in the context of essential oil production?
- Testing essential oils for purity and adulteration
- Re-distilling an essential oil to remove unwanted or hazardous components (Correct answer)
- Blending multiple oils into a standardized single product
- Adding a carrier oil to reduce an essential oil's concentration
Correct answer: Re-distilling an essential oil to remove unwanted or hazardous components
Rectification is the process of re-distilling an essential oil to remove undesirable components, such as the removal of certain camphor fractions for safety reasons.
Question 2: Which extraction method produces a 'concrete' as an intermediate product before yielding an absolute?
- Steam distillation
- CO2 extraction
- Solvent extraction (Correct answer)
- Cold pressing
Correct answer: Solvent extraction
Solvent extraction first produces a concrete (a waxy semi-solid mixture of waxes and aromatic compounds), which is then washed with alcohol to yield an absolute.
Question 3: Rose essential oil produced by steam distillation is commercially known as:
- Rose absolute
- Rose otto (attar of roses) (Correct answer)
- Rose concrete
- Rose CO2 select
Correct answer: Rose otto (attar of roses)
Rose essential oil obtained by steam distillation is called rose otto or attar of roses, distinguishing it from rose absolute which is produced by solvent extraction.
Question 4: What is the primary advantage of CO2 supercritical extraction over conventional steam distillation?
- It has a significantly lower cost of production
- It requires faster extraction times
- It extracts at lower temperatures, preserving heat-sensitive aromatic compounds (Correct answer)
- It requires substantially less plant material per batch
Correct answer: It extracts at lower temperatures, preserving heat-sensitive aromatic compounds
CO2 supercritical extraction operates at lower temperatures than steam distillation, preserving heat-sensitive compounds and producing an extract truer to the original plant's natural chemistry.
Question 5: Which solvent is most commonly used in the first stage of solvent extraction of aromatic plant material?
- Water
- Hexane (Correct answer)
- Ethyl alcohol only
- Acetone
Correct answer: Hexane
Hexane is a common hydrocarbon solvent used to dissolve aromatic compounds from plant material in solvent extraction, after which it is removed to leave a concrete.
Question 6: What does the term 'expression' describe as an essential oil extraction method?
- The distillation of roots and woody plant material
- The mechanical pressing or scraping of plant material to physically release oils (Correct answer)
- The use of alcohol to draw out aromatic compounds from plant matter
- The sublimation of volatile aromatic compounds from dried herbs
Correct answer: The mechanical pressing or scraping of plant material to physically release oils
Expression (cold pressing) mechanically presses or scrapes plant material—typically citrus rinds—to physically release the essential oil without heat or solvents.
Question 7: Which analytical test is best suited to verify that no solvent residues remain in a solvent-extracted essential oil?
- Specific gravity measurement
- Optical rotation test
- Gas chromatography-mass spectrometry (GC-MS) (Correct answer)
- Evaporation test on blotter paper
Correct answer: Gas chromatography-mass spectrometry (GC-MS)
Gas chromatography-mass spectrometry (GC-MS) can detect trace solvent residues and fully verify the chemical composition of an essential oil sample.
Aromatherapy Essential Oil Extraction Methods 2
What does 'rectification' mean in the context of essential oil production?