The Silent Enemy of Sensory Enjoyment – Olfactory Fatigue

George F Manska, CR&D Arsilica, Inc.

What is it?  Olfactory fatigue, also called olfactory adaptation also referred to as nose-blindness, is a phenomenon in which olfactory receptors decrease in sensitivity due to prolonged odorant exposure, resulting in the inability to perceive, differentiate, or identify aromas. Olfactory fatigue is a dynamic, adaptive, protective mechanism which prevents sensory overload from continuous exposure. It allows the olfactory system to adapt to constant background odors while maintaining sensitivity to new or changing odors, constantly on the vigil to detect potential dangers (fire, poison) or opportunities (Gram’s apple pie).

Mechanisms of Olfactory Fatigue:  Several mechanisms are involved in olfactory fatigue:

• Receptor Desensitization: Olfactory receptors in the nasal epithelium detect specific odor molecules. Prolonged exposure to the same odorant results in receptors become less responsive to that specific odor.
• Neural Adaptation: Signal transmitting sensory neurons become less responsive to the same odor signal over time.
• Central Processing: As brain receives repetitive odor signals, it reprioritizes to focus on changing sensory information, contributing to the perception of reduced sensitivity.
• Peripheral Factors: Depletion of neurotransmitters and refreshing nasal epithelium mucous layer.

Signs of Olfactory Fatigue:  Ethanol (alcohol) is an anesthetic and numbs olfactory receptors.  Olfactory fatigue occurs without awareness, is painless and gradual, with no warning signs.  It’s seldom discussed at tastings, and few know it exists, even though we have all experienced it.  Few are concerned, “I never noticed it.  If I don’t know it’s there, it’s not an issue.”  Many deny, “My nose is good, I’ve been drinking (type of spirit) for a long time and never bothered me.”  Three questions indicate you are most likely in some stage of olfactory fatigue.

• Why don’t I smell anything?
• Why can’t I identify this aroma?
• Why does every sample smell the same?

Memory Distracts:  Of course, the next question asked is “It’s (type of spirit, e.g. bourbon).  What should I smell?”  Experiential memory comes to the rescue by recalling your last (name of spirit type) tasting and the attending aromas, and you begin to search for them.  Now you are no longer evaluating the sample in front of you, but attempting to validate a spirit you are familiar with while nosing a new, different spirt. 

Ignorance and Denial is Proportional to ABV:  High ABV (alcohol by volume) of spirits (40%+), is too much nose-numbing, pungent, anesthetic for the human olfactory to handle.  Wine tasters have frequent bouts of olfactory fatigue.  Wine ABVs have increased some over the years from 5-9%  to 8-16%, with fortified wines up around 22%.  Wine tasters seem to be open about nose blindness.  It is a common occurrence during tastings and competitions, and wine store tastings, yet no one seems ashamed to mention they are experiencing nose blindness.  

Spirits drinkers are another story, as machismo permeates whiskey clubs, clouding objectivity, punctuated by the fact that four times the alcohol is present in spirits as opposed to red wine.  Spirits drinkers are reluctant to admit they have an aroma detection problem when it occurs, even when tasting cask strength spirits.  Does olfactory fatigue occur in spirits drinkers?  You bet it does, on steroids

These factors strongly suggest that spirits, with their higher ABV and concentrated aromas, lead to olfactory fatigue.  Olfactory fatigue and volatile compounds go hand-in-hand.  More volatile compounds = more numbing of ORNs (olfactory neuron receptors), lead to quicker onset.  The chart clearly points to ethanol as the most volatile culprit.

How do we avoid olfactory fatigue and enhance smell-ability?

• Stop using tulip glasses, they shove concentrated ethanol up your nose, obscuring aromas and flavors.  Use a tumbler, or better still, a glass designed to avoid olfactory fatigue such as NEAT (in full disclosure, invented by the author).  Drinking 40% ABV spirits from a glass designed for 22% fortified wine copita creates a nose-bomb
• Walk away, go outside, get a fresh breath of air, don’t smoke, blow your nose, don’t return for 4 minutes.  The only way to reset your nose is to allow the mucous layer to replace and wash the ethanol molecules away. 
• Forget about coffee bean myths, smelling your armpit or the crook of your arm, and smelling salts.  Nothing but time away from the exposure will allow the mucous layer on the epithelium to reset.

Did you come to a tasting to drink, or to enjoy the nuances the distillers created in their spirits?  Discipline and an open-rimmed glass will enhance the experience.

Note: Enrolled NEATNEWS subscribers are entitled to 10% discount on all purchases and free
shipping over $55 for as long as you are enrolled. Coupon code: ILUVNEAT

Bio:  George F Manska, CR&D, Arsilica, Inc.

Qualifications:  Published sensory science researcher, entrepreneur. BSME, NEAT glass co-inventor

Mission: Replace myth and misinformation with scientific truth through consumer education.  

Comments Welcome – Contact:  george@arsilica.com, phone 702.332.7305. 

More Information: www.theneatglass.com/shop