CSA CSA Flavor Science & Sensory Chemistry 2 — Questions and Answers
Question 1: The detection threshold of a flavor compound is defined as the minimum concentration at which what percentage of a trained panel can correctly identify it above chance?
- 50% (Correct answer)
- 25%
- 75%
- 100%
Correct answer: 50%
By convention, the detection threshold is the concentration at which 50% of assessors can detect the stimulus above chance, often determined via a psychophysical dose-response curve.
Question 2: Which phenomenon explains why prolonged exposure to a single aroma causes a temporary decrease in its perceived intensity?
- Sensory adaptation (Correct answer)
- Cross-adaptation
- Masking
- Fatigue carry-over
Correct answer: Sensory adaptation
Sensory adaptation is the temporary reduction in receptor responsiveness following continuous or prolonged exposure to a stimulus, causing the perceived intensity to diminish.
Question 3: Which class of volatile compounds, formed by the reaction of alcohols and organic acids, is largely responsible for fruity aromas in wines and spirits?
- Esters (Correct answer)
- Aldehydes
- Ketones
- Terpenes
Correct answer: Esters
Esters such as ethyl acetate and isoamyl acetate are formed by esterification reactions during fermentation and aging, contributing the fruity notes characteristic of wines and spirits.
Question 4: The OAV (Odor Activity Value) of a compound is calculated as:
- Concentration ÷ Detection threshold (Correct answer)
- Detection threshold ÷ Concentration
- Log(Concentration) × Threshold
- Concentration × Perception threshold
Correct answer: Concentration ÷ Detection threshold
OAV = concentration of the compound in a food divided by its detection threshold; compounds with OAV > 1 are considered likely contributors to the overall aroma profile.
Question 5: Bitterness suppression by salt (NaCl) is a well-documented taste interaction. What is the primary mechanism proposed for this effect?
- Sodium ions block bitter taste receptor channels (Correct answer)
- Chloride ions bind quinine directly
- Salt elevates salivary pH neutralizing bitter acids
- Sodium reduces saliva viscosity
Correct answer: Sodium ions block bitter taste receptor channels
Sodium ions are believed to suppress bitterness by blocking amiloride-sensitive ion channels and possibly by directly inhibiting T2R bitter receptor signaling at the taste cell level.
Question 6: Which technique is used in flavor chemistry to determine which specific volatile compounds most significantly contribute to a food's aroma by combining GC-MS with olfactometry?
- GC-O (Gas Chromatography-Olfactometry) (Correct answer)
- SPME-MS
- HPLC-DAD
- Electronic nose (e-nose)
Correct answer: GC-O (Gas Chromatography-Olfactometry)
GC-O combines separation by gas chromatography with simultaneous sniffing at the detector port, allowing trained assessors to identify and rate specific aroma-active compounds as they elute.
CSA CSA Flavor Science & Sensory Chemistry 2
The detection threshold of a flavor compound is defined as the minimum concentration at which what percentage of a trained panel can correctly identify it above chance?