©2024, Randy Mosher/New Brewer magazine
Beer simply thrills the senses. No other beverage has more depth and variety or offers a greater range of sensations. Based on its chemistry, it is by far the most complex beverage on earth. Exciting as it is for enthusiasts, having some tasting expertise makes it even more rewarding. For the brewer, beer is a very challenging product to make and evaluate; tasting skills are mandatory for the job.
There are all kinds of expert tasters in beer: brewers, QA panelists, reviewers and judges. Each have different, overlapping skills. Some seem to have extraordinary powers to pick out the subtlest nuances or conjure an emerging recipe idea in the mind without brewing a drop. What makes these people so special and are they really all that different from the rest of us? After five years of intensely studying the science of tasting, I have some ideas.
Are we any good at this?
Here’s the science: we think we’re terrible, but we’re actually not. You might say, “Well, sure, people are fine, but not me.” I have friends who insist they’re mostly insensitive to smells and tastes. Some may have deficits like allergies or sinus issues, but honestly, few have put much effort into it.
Taste and mouthfeel are frontline defenses against danger as well as potent motivation for eating, so they’re highly protected, varying little from person-to-person. The one exception is bitterness. With 26 receptors and multiple copies including genetic variations affecting sensitivity, we all vary a bit. You’ve probably heard about “supertasters,” whose differences are based on one or possibly two bitter receptors tweaking our sensitivity to bitter compounds in vegetables like broccoli. Because these genetic mutations seem to be linked to some other characteristics, supertasters are also more sensitive to the trigeminal burn of alcohol, chile and other irritants. About 21% of the population qualifies, while another 26% or so are considered “non-tasters,” with the remaining 53% in the middle. By the way, these characteristics have absolutely nothing to do with smell sensitivity.
In terms of smell, humans are often denigrated as being much poorer than bears or dogs. Compared to mice, it’s true we have only a third as many working receptor types, but we have way more copies. It’s a fair bargain, because their extra receptors involuntarily control their behavior, while our cognitive brain does these tasks with far more flexibility—and free will. Each creature has its own lifestyle, and its sensory systems are adapted perfectly to it.
Besides, we are actually pretty capable. We’re super-sensitive to food odors, and may be the only creatures on the planet that can smell the odors of cooking. Tested at scent-tracking, blindfolded participants on all fours have done pretty good at following a zigzag chocolate-drenched trail across a grassy field, swinging their heads side-to-side to find the way forward.
Smell is by far the most variable sense. With nearly 400 olfactory receptor types, there’s massive opportunity for genetic variations. Smell works by creating patterns of responses to odorous chemicals. The olfactory bulb clarifies these and presents them to the brain for identification. The brain then searches memory for a match, and when it’s located in memory it comes tagged with value, context and other qualities from previous encounters. The receptor pattern is just a tool for recognition, and the actual patterns of our olfactory receptors’ responses to chemistry never enter the brain. For most smells differences in response patterns don’t matter all that much, since what we share is the concept of, say a ripe peach. As a result, we don’t much notice differences in everyday life.
While most odors are composed of multitudes of different chemicals, some odors stimulate very few or even a single receptor. When one of them is less than fully functional, it can make us less sensitive, perhaps by a factor of 1,000. Such chemicals seem to be especially common in problematic “off-flavors” in beer and other products, with about one in twenty sensory panelists being insensitive to buttery diacetyl, for example.
One final reassurance. While perfumers and sommeliers may appear to have superhuman powers, the research confirms that they start out pretty much like the rest of us, although perhaps with more enthusiasm. Their expertise is hard-won, with years of self-study or apprenticeship required to become certified experts in their realms. Tellingly, their subject knowledge is not very transferable. Groups like wine experts generally do little better than average when tested on everyday smells or unfamiliar specialties like coffee. The biggest obstacle sometimes is thinking something becoming an expert is impossible for you. It’s not.
Let’s break it down
So what physiological and psychological tasks do tasters master to become proficient? Nature and nurture have provided us with a baseline of capabilities, fortified over the years by various kinds of learning.
The first and most fundamental characteristic is threshold: how little of a compound can you actually smell? In tasting situations this is generally presented as a task to choose which of three samples differs from the other two. It’s a purely sensory task; neither recognition nor language are required. Each chemical has an average human detection threshold in a particular matrix (like beer water, etc.); these vary by many orders of magnitude between chemicals. We humans show a range of sensitivity to them based mostly on the genetics of our receptors.
It seems simple, but a threshold is actually quite a complex metric. While it is a kind of a baseline, thresholds don’t correlate well to how intensely odors are perceived at higher doses. Also, in order to cover a wide range of concentrations we actually recruit many different receptor types at higher quantities than at lower ones, and their response patterns must be learned over time, which we unconsciously do.
The second step, recognition, goes beyond the odor-receptor interactions and moves into the brain. At this point, the response pattern finds a match in memory. This is just “I know this,” without involving language—something scientists call “the tip of the nose” phenomenon, where we can’t quite put a word to a familiar smell. Recognition largely involves the brain’s limbic system where memories and hedonic valuation are processed, although there’s a cognitive component too. We have two memory systems: the purely sensory one involved here and a semantic one involving categorization and language. Sometimes, discrimination between odors is needed, involving what neuroscientists call “pattern separation.” Using this neural tool, we can focus on the object of interest against a background—just think of your attention as an illuminating spotlight.
Finally, it’s identification time. This cognitive process puts a name, context and more to the sensation. It’s a challenge. The sense of smell, since the beginning of life on earth, is designed to move us towards or away from the odor of interest; words rarely help with that. Because identification is mainly a cognitive process, it’s something that can be learned; this is what really differentiates the experts from the rest of us. In addition to identification, it also involves categorization and meaning. In wine expertise, its semantic structure is based on prototypes: varietals first, then location and then vintage and weather, plus other attributes. In beer, we tend to classify by styles, although experienced brewers also can also translate sensory impressions into ingredients and processes.
How are the experts different?
There’s been quite a bit of study on this topic, especially regarding wine experts. A few general things have come to light. First, their absolute sensitivity, in terms of thresholds, is little better than the general public, and is little improved by experience. As a mostly physiological process, it’s mostly unresponsive to learning.
Expert tasters learn to use proper technique and approach every taste with the right frame of mind, which does improve performance. But the biggest gains with experience are in recognition, which relies heavily on our sensory-specific memory system, and even more so in naming and contextualizing. Expert sensory impressions transcend qualitative descriptors, and are accompanied by a trove of subject-relevant semantic information, learned piece-by-piece over time. Novices however, tend to stick to hedonic terms in their descriptions.
A lot of what makes expert knowledge different is categorization. Humans are extraordinarily good at this, and the possibilities seem unlimited. Think of each recalled memory as having one or more records like index cards with identity, value and context, often of incredible specificity. In wine, a sniff and a sip can call up a memory of not only the grape variety or blend, but the country, region, geology, side of the river, sunny or shady side of the hill and possibly even the estate and the year in which the grapes grew.
It is believed that experts have a highly active sensory memory. This may result in a heightened vividness of imagery, not limited to one or two senses. Novices typically have high vividness only for visual experiences, with smell and other senses lagging behind.
Olfactory learning may be a bit of a “use it or lose it” situation. Olfactory stimulation has been shown to alter and expand our complement of olfactory receptors, and even help with recovery from smell loss driven by COVID or similar causes. There’s also a lot of evidence that this kind of learning leads to visible changes in the brain within just weeks. Studies have shown more gray matter in certain parts of the brain and in the olfactory bulb, as well as increased brain activity in frontal regions when scanned by fMRI. As a result, experts are believed to use their processing more efficiently and with less effort, and are more able to successfully direct their attention to the task at hand.
Another differentiator is vocabulary. While there are many ways to characterize sensory impressions, each discipline has its own lexicon allowing all the practitioners to use the same terms. These can be a challenge, as it’s been shown that words can overshadow sensations. Reading a book and memorizing the sensory glossary first may actually make your journey harder, not easier, as each of us has specific sensory memories we use to characterize particular aromas based on our life experiences. For me, I had read that acetaldehyde smelled of green apple, so for years I looked for the Jolly Rancher® without success. One day, a smell triggered a visual memory of the bottom of a lawnmower that had just run over some overripe apples. Bingo! Later, I learned the other clues: pumpkin guts, latex paint, flower shop. So don’t get ahead of yourself. Get your nose in stuff as much as you can. You can easily learn the “right” terms later.
Do you know what you don’t know?
We’re all different, but do you know how unique you actually are in terms of tasting? If you’ve been on the scene for a while and participate in regular tasting sessions or competition judging, you may have some idea. Chances are you have at least one weakness. If everyone sitting around the table but you is getting diacetyl, you may be one of the five percent blind to it. There are some tests for thresholds, but to fully calibrate yourself would be quite an odyssey that you couldn’t do by yourself. On the flip side, you may have some minor super-powers. I’m blessed/cursed with extra sensitivity to musty/moldy—I’m the guy you want sniffing the wine cork in the restaurant, but please don’t serve me beets.
Smell has been described as the “mute sense,” in that it’s not always front and center as vision and hearing are. The lesson here is that it’s extraordinarily responsive to attention. With its own secret language, it just blasts raw sensory data into your emotional brain with no clues to help decode it. You have no choice but to engage smell on its own terms. Let it take you where it wants to, and use that information to bridge to recognition, then identification. Those weird memories have real meaning. It can be a bit meditative, but listen to your inner taster: it’s never wrong. Think about tasting as a mindset where a number of things need to happen. Get yourself relaxed, clear your mind, focus your expectations only as much as you need to, then fully engage with your senses.
Most of us don’t practice enough. Could you blind-identify blueberries vs. blackberries? Half the population can’t even identify a banana without seeing it. A fun event is to come back from the grocery store with a bunch of different fruits, herbs and spices, and put them in opaque cups with coasters for lids. Lift and sniff, without peeking. How many can you get? I often say that driving around with your car windows open at lunchtime and smelling what’s cooking qualifies as a tasting exercise.
Tasting and creating: a word on technique
As brewers we need to successfully engage both in tasting and in the act of flavor creation. These are just two sides of the same coin. Our brains helpfully package taste, smell, mouthfeel, vision and more into a single experience called flavor. As a taster, you have to try to unbundle things as much as you can. On the other hand, you have to appreciate that all the little, single things you put together into a beer will be perceived holistically, so it’s the sum of it all that really matters.
A proper approach to tasting can really help you get the most out of that glass in front of you. A sniff is actually a neural event that synchronizes brain waves between the olfactory bulb and the olfactory cortices, making olfaction faster and more effective. Try to just do what seems natural—small, gentle sniffs are best. Also be aware of the importance of retronasal olfaction, in which vapors from the swallowed liquid is gently exhaled through the nose, lips closed. The reverse airflow actually switches the brain’s wiring, giving you quite a different take. The retronasal will be processed as a multimodal flavor sensation more than it is a smell. And the liquid will have changed, too. Since our mouths are teeming with active chemistry, compounds are lost, gained and transformed during the few seconds of a taste. Also attend to the way the taste changes over perhaps 30 seconds or so—it’s all important.
On the creating side, one useful skill to cultivate is odor mental imagery. This was previously dismissed as an impossibility, but it turns out that chefs, perfumers, flavorists and brewers can do this quite well. Being able to create a multisensory image of a beer in your head saves you a lot of time when you’re working through different ideas.
Acquiring real expertise involves a lot of moving parts and pieces and takes a real investment of time and effort over the long haul. It can seem like a very high hill to climb, but the trip is pleasurable and exquisitely rewarding. Best, there’s always a beer at your side.