CFC Flavor Extraction & Isolation Techniques 1 — Questions and Answers
Question 1: Which extraction technique uses carbon dioxide above its critical temperature and pressure to extract flavor compounds without leaving solvent residues?
- Supercritical fluid extraction (SFE) (Correct answer)
- Steam distillation
- Liquid-liquid extraction
- Soxhlet extraction
Correct answer: Supercritical fluid extraction (SFE)
Supercritical fluid extraction using CO₂ above 31.1°C and 73.8 atm produces a solvent-free extract since CO₂ is a gas at ambient conditions.
Question 2: In steam distillation of essential oils, the principle that allows compounds with boiling points above 100°C to co-distill with water is best explained by:
- Dalton's law of partial pressures (Correct answer)
- Henry's law of gas solubility
- Raoult's law of vapor pressure lowering
- Graham's law of effusion
Correct answer: Dalton's law of partial pressures
Dalton's law states that the total vapor pressure equals the sum of each component's partial pressure, allowing the mixture to boil below 100°C even if individual boiling points are higher.
Question 3: Solid Phase Microextraction (SPME) is classified as a:
- Non-exhaustive, equilibrium-based technique (Correct answer)
- Exhaustive, partition-based technique
- Continuous flow distillation method
- Pressurized solvent extraction method
Correct answer: Non-exhaustive, equilibrium-based technique
SPME is non-exhaustive because it equilibrates a coated fiber with the sample matrix without extracting all analytes, making it useful for headspace and direct immersion sampling.
Question 4: Cold pressing is the preferred extraction method for citrus peel oils primarily because it:
- Avoids heat-induced degradation of thermolabile terpenoids (Correct answer)
- Produces higher yield than steam distillation
- Removes all non-volatile impurities automatically
- Works well for extracting water-soluble flavor compounds
Correct answer: Avoids heat-induced degradation of thermolabile terpenoids
Mechanical cold pressing preserves heat-sensitive aroma compounds such as limonene and linalool that would degrade or rearrange under the thermal conditions of distillation.
Question 5: Enfleurage is a traditional flavor/fragrance extraction technique that relies on:
- Absorption of volatile compounds into odorless fat at ambient temperature (Correct answer)
- Distillation of flower petals with water vapor
- Soaking plant material in cold alcohol
- Pressing petals under hydraulic pressure to collect juice
Correct answer: Absorption of volatile compounds into odorless fat at ambient temperature
Enfleurage traps delicate floral volatiles by laying petals on fat (pomade) that absorbs the aroma compounds, after which the saturated fat is washed with alcohol.
Question 6: When performing liquid-liquid extraction (LLE) of flavor compounds from an aqueous food matrix, which solvent property is most critical for good selectivity?
- Log P (partition coefficient) matching the target analytes (Correct answer)
- High boiling point to allow reflux
- Miscibility with water to ensure homogeneous contact
- Low surface tension for improved wetting
Correct answer: Log P (partition coefficient) matching the target analytes
The log P of the extraction solvent determines how well it partitions lipophilic versus hydrophilic flavor compounds, directly governing extraction selectivity.
Question 7: Which adsorbent is most commonly used in headspace trap (dynamic headspace) collection for flavor analysis due to its thermal stability and low artifact generation?
- Tenax TA (Correct answer)
- Activated charcoal
- Silica gel
- Alumina
Correct answer: Tenax TA
Tenax TA (poly(2,6-diphenyl-p-phenylene oxide)) is preferred for headspace trapping because it efficiently adsorbs volatiles, releases them cleanly during thermal desorption, and produces minimal background artifacts.
CFC Flavor Extraction & Isolation Techniques 1
Which extraction technique uses carbon dioxide above its critical temperature and pressure to extract flavor compounds without leaving solvent residues?