Instrumentation & Calibration Flashcards

In gas chromatography–olfactometry (GC-O), what does the human assessor do?

Answer: Sniffs the column effluent to describe odor-active compounds

In GC-O, assessors sniff the separated compounds at an odor port to find which ones are odor-active.

Which GC-O technique serially dilutes an extract until an odor can no longer be detected?

Answer: Aroma Extract Dilution Analysis (AEDA)

AEDA assigns flavor dilution factors based on the highest dilution at which an odorant is still perceived.

What is the main limitation of an electronic nose compared with a trained human panel?

Answer: It detects volatile patterns but cannot directly report perceived odor quality

E-noses classify volatile fingerprints by sensor response, but they must be trained against sensory data to mean anything about perception.

Electronic nose sensors often drift over time. What is a common way to correct this?

Answer: Measure reference standards regularly and apply drift correction

Regularly running reference samples allows drift to be detected and mathematically corrected.

For GC-MS identification of an aroma compound, which combination gives the most confident identification?

Answer: Matching mass spectrum and retention index to an authentic standard

Confirmed identification needs agreement in mass spectrum, retention index, and ideally odor against an authentic reference compound.

An internal standard is added to samples before GC analysis mainly to:

Answer: Correct for variation in extraction and injection

An internal standard corrects for losses and injection variability, which improves quantitative accuracy.

Headspace SPME is often used before GC analysis of food aroma because it:

Answer: Extracts volatiles without solvent

Solid-phase microextraction pulls volatiles from the headspace onto a coated fiber without solvent.