Olfactory perception is a key mechanism of wine tasting, as smelling the wine tells one a great many characteristics of a given wine which contribute significantly to the overall wine tasting experience. Do experts possess greater olfactory perception than novices? Studies have shown that experts possess greater ability to identify, discriminate, and recognize through olfactory mechanisms than novices, though at the same time showing that olfactory sensitivity is the same between the two groups. In other words, experts and novices are both able to smell the wine at the same threshold level, however experts are better able to tease apart the complex nuances of the wine than novices.
Many believe that this ability to recognize and identify more odors in wines by experts is due to education and practice, as a result of repetitive exposure to many different styles of wine. In fact, studies have shown that repetitive exposure to certain odors can increase olfactory sensitivity, so it could be hypothesized that wine experts have a lower olfactory perception threshold than novices. Studies have also found that each nostril behaves slightly different from one to the other, leading some to believe that perhaps wine experts have a greater ability to utilize this more sensitive nostril than novices.
Mechanistically, there is a significant difference in sensitivity and perception depending upon exactly how one inhales. When one inhales normally, only 15% of the air coming in passes over the epithelium in the nasal cavity. Since odor is perceived when gas is exchanged from the air into the epithelial cells, one should aim to maximize the amount of air passing over these cells for greater gas transfer.
How does one do that?
By sniffing instead of simply inhaling normally, one is significantly increasing the amount of air entering the nasal cavity, thereby significantly increasing the amount of gas exchanged at the air/epithelial boundary. This ultimately increases the olfactory systems’ ability to detect volatiles and other odors. Interestingly, the mechanisms of sniffing and normal smelling are activated by different parts of the brain, therefore it can be argued that experts are better able to activate the portion of the brain than novices, which may or may not be a factor of experience.
Try smelling your wine by simply breathing in normally. Then, after a brief break, try smelling the wine again by sniffing rapidly for the same length of time as prior. Do you notice a difference?
The goal of the study presented today aimed to examine the differences in olfactory perception between wine experts and novices, and to determine if there is a difference in perception based on nostril location (left or right) and if there is a difference in this nasal lateralization between experts and novices.
40 participants were split up into two groups and age-matched: wine experts and wine novices. Each group had an equal number of males and females, to look for possible gender differences. Experts were recruited from the French County Institute of Wine and Taste. The average age of the expert group was 50 years and 3 months (standard deviation of 12 years), and the average age of the novice group was 51 years and 6 months (standard deviation of 11 years). All participants claimed normal smell sensitivity and no history of chemical exposure that would potentially damage olfactory perception ability.
Wines used in the study were Savagnin 2005 (12.8% alcohol; Benoit: Pupillin, France), Morgon 2007 (12.5% alcohol; Gauthier: Villié-Morgon, France), and Riesling 2007 (12.5%; Lorentz; Bergheim, France). A dilution series was prepared for each wine using deionized water. The full series included 20 steps, with step 1 being the most dilute wine (i.e. mostly water with a little wine) and step 20 being the most concentration (i.e. mostly wine with a little water). 50mL of each dilution was placed into black wine glasses (to eliminate the variable of color/vision). A 50mL glass of deionized water was used as the negative control.
The experiment was divided into three different sessions over the course of three weeks.
- Session 1: Right nostril testing using Riesling and left nostril testing using Morgon.
- Session 2: Right nostril testing using Savagnin and left nostril testing using Riesling.
- Session 3: Right nostril testing using Morgon and left nostril testing using Savagnin. The third session also included a butanol control sensitivity test.
Each session lasted 1.5 hours with a 15 minute break in between right and left testing.
After each session, participants were asked to score irritant properties and overall enjoyment of the wine on a 0-10 scale. For irritant properties, 0 was not irritant and 10 was strongly irritant. For overall enjoyment, 0 was very unpleasant and 10 was very pleasant.
During each session, whichever nostril was not being tested was plugged. The sessions consisted of force-choice trials: each trial consisted of 2 glasses; one being the negative control (water) and the other being one of the wine dilutions. Participants were asked to identify by smell which glass contained the wine. Testing of each wine began at the most dilute concentration, so as to avoid olfactory receptor adaptation. Each wine concentration was tested 3 times. Threshold was determined when a participant correctly identified the glass containing wine three times at two consecutive concentration levels. According to the authors, the probability of guessing correctly was 1 out of 64.
- Butanol detection tests showed there was no significant effect of expertise, gender, or nostril location.
- Novices had lower wine detection thresholds than experts.
- In other words, novices were more sensitive to detecting if a glass contained wine or water than experts.
- There was no significant effect of gender or nostril location for any of the wines.
- Novices had a lower detection threshold in the left nostril than experts.
- There were no significant differences between experts and novices in regards to the detection threshold of the right nostril.
- The detection threshold for the Savagnin wine was lower than the other two wines for both groups and either nostril.
- Novices scored wines as more irritating than did the experts.
- There was no significant gender or nostril effect, nor was there any significant interaction between group and nostril.
- Novices scored wines as less pleasant than did the experts.
- There was no significant gender or nostril effect.
- Experts rated wines as more pleasant than did the novices using the right nostril.
- There were no significant differences with the left nostril.
What do these results mean?
The results of this study found that novices appear to have greater sensitivity to wine than experts when using the right nostril, though there were no differences between the groups using the left nostril. In regards to irritation, novices found the wine to be more irritating to the nose than did the experts. In regards to overall pleasantries, novices found the wine to be less pleasant overall than did the experts, and experts also found the wine even more pleasant using their right nostril.
According to the authors of this study, these results indicate that there is a more important lateralization aspect to wine tasting for novices than there is for experts. In other words, one side of the nose is more sensitive to novice tasters than experts, who have the ability to sense wine equally in both nostrils. This result actually turned out to oppose the original hypothesis of this study, which stated that experts would have greater olfactory sensitivity to wine than novices. The authors suggest that this result may be due to the fact that experts are trained to use both nostrils evenly, whereas novices will detect the wine better on whichever nostril is more sensitive to odor cues.
Other studies have found that olfactory sensitivity may not be a requirement for wine characteristics identification, but that the development of cognitive strategies and attention to detail is what sets the two groups apart. The current study did not examine this hypothesis, though it could potentially explain the results found therein.
I have no formal training in this area of neuroscience (other than what I’ve read in papers) so I could be light years out of the ballpark, but one idea that I was thinking was that perhaps these results could be explained by experience and time. Specifically, perhaps the odor of wine is so novel for beginners that they can tell pretty quickly if there is something slightly “off” about the glass that they smell. Of course, when I say “off”, I don’t mean to say that the wine was bad, but that it is different than the water or other beverages they are used to smelling.
Perhaps with wine experts, the novelty of the general wine odor has since worn and they have been relatively desensitized in that regard. I would like to see a study that followed an individual from “wine novicehood” to “wine expert”, all the while measuring olfactory sensitivity and odor perception/identification throughout the entire course of development. This would obviously be a long-term study, but I would think there could be a fair amount of interest to participate in this type of study.
I would also like to see the study repeated with a larger sample size, as at the current size of 20 participants per group, the results may not be generalizable to the greater population as a whole.
What about you all? How would you interpret the results of this study? There’s a lot more work to be done, so there could be many different interpretations worthy of further research. Please tell us what you think by commenting!
Source: Brand, G., and Brisson, R. 2012. Lateralisation in wine olfactory threshold detection: Comparison between experts and novices. Laterality 17(5): 583-596.