Flavor Extraction & Isolation Techniques Flashcards

Microwave-assisted extraction (MAE) of flavor compounds is based primarily on which heating mechanism?

Answer: Dielectric heating of polar molecules and water within the plant matrix

Microwave energy causes rapid dielectric heating of polar molecules (especially water) inside the plant matrix, rupturing cell walls and releasing intracellular flavor compounds into the extraction solvent very quickly.

Ultrasound-assisted extraction (UAE) of flavor compounds improves extraction efficiency primarily through:

Answer: Acoustic cavitation that disrupts cell walls and increases mass transfer

Ultrasound creates acoustic cavitation—rapid formation and collapse of microbubbles—that generates intense local pressure and temperature, physically disrupting cell walls and enhancing solvent penetration and mass transfer.

Preparative HPLC is used to isolate pure flavor reference standards primarily because it offers:

Answer: High resolution separation with scalable throughput and fraction collection capability

Preparative HPLC uses larger-diameter columns with higher flow rates and automated fraction collectors to isolate milligram to gram quantities of pure flavor compounds that can then be used as authenticated reference standards.

When selecting an organic solvent for extracting aroma compounds from a complex food matrix, which pair of properties is most important to evaluate first?

Answer: Selectivity for target analytes and low boiling point for easy removal

Selectivity ensures target aroma compounds are efficiently extracted with minimal co-extractants, while a low boiling point (e.g., diethyl ether, pentane) allows solvent removal by gentle evaporation without concentrating the extract thermally.

Stir bar sorptive extraction (SBSE, e.g., Twister®) offers a significant advantage over SPME for flavor profiling because it:

Answer: Provides a much larger volume of sorptive phase, improving sensitivity for trace aroma compounds

SBSE's polydimethylsiloxane (PDMS)-coated stir bar contains 50–250 times more sorptive phase than a SPME fiber, resulting in proportionally higher analyte enrichment and lower detection limits for trace flavor aroma compounds.

In the context of flavor isolation, the term 'exhaustive extraction' means that:

Answer: Essentially all of the target analyte is removed from the sample matrix into the extract

Exhaustive extraction techniques (like Soxhlet or PLE) aim to quantitatively transfer nearly 100% of the target analyte out of the matrix, enabling accurate quantification, in contrast to equilibrium (non-exhaustive) methods like SPME.

Which factor most critically determines the partition of a flavor compound between the SPME fiber coating and the sample headspace during static headspace SPME?

Answer: The distribution constant (Kfs) between the fiber coating polymer and the headspace gas

The fiber-headspace distribution constant (Kfs) quantitatively describes how strongly a compound partitions into the PDMS or other polymer coating relative to the gas phase, directly determining extraction efficiency and sensitivity.