No matter how tight your brewing budget, there's one high-end tool that you can afford. Used properly, it will greatly improve the quality of your beer. It's a sophisticated, versatile device that can help you accurately evaluate your beer. That tool is you. By using your senses and acting as your own objective taster, you can improve your homebrewing skills.
We use all five of our senses when we evaluate beer. That is because the appearance (sight), aroma (smell), taste, mouthfeel (touch), and even the sound (hearing) beer makes when you pour it in the glass are all key components of the sensory quality of beer.
There's a sixth sense, too. Sometimes called the "common chemical sense," the trigeminal nerve (found in the mouth) responds to irritants. It is also stimulated by components in beer such as carbon dioxide and astringent phenols.
Our sensory equipment is the ideal tool for quality assurance. It is reliable, sensitive...and cheap. In general, human sensitivities to chemical stimuli - the compounds in beer with a taste or smell or the ones that act as irritants - are normally distributed. That means most of us have more or less the same sensitivity to the bitter taste of isohumulones or the floral smell of Chinook hops.
A few people have particularly low or high sensitivities. And there are compounds for which some individuals may be anosmic (can't smell them) or agueusic (can't taste them), in the same way as some individuals are color blind. But these compounds are relatively few and are not typically found in beer. So relax, because on average when it comes to tasting or smelling most of the compounds found in beer, we all pretty much play with the same (sensory) deck of cards.
Know Your Own Mind
What makes a person a good taster is experience – the size of the sensory database accumulated in memory. In other words, how many beers did that person "taste" - not "drink" - over the years? Once you have tasted several beers with diacetyl, it becomes easy to pick out the buttery smell associated with it in your own beers. The same goes for most off-flavors such as the skunky character of lightstruck beers or the apple/cardboard smell of oxidized beers.
Also important are the ability of the person to concentrate and the person's motivation. Don't let human psychology play tricks on you. As a homebrewer, you might be your own worst enemy because you tend to lose your objectivity when you taste your own beers. So much effort goes into brewing your own that it will taste good to you - regardless. Train yourself to become an objective taster, and don't be afraid to get a second opinion every once in a while. The comments and suggestions of others can help make you a better (more objective) taster.
There is a simple way to train yourself to use your senses for quality assurance (or damage control) purposes. The technique is called descriptive analysis or flavor profiling. It produces a sensory ID for each beer by identifying the key sensory attributes in the beer and quantifying them on an intensity scale.
Descriptive panels in the large professional brewing industry go through the following steps:
- First, the panel gets together and, under the guidance of a panel leader, generates terms describing the sensory attributes of the product under study (for example, specialty lagers), with a few representative samples.
- The experimenter then tries to develop reference standards for each of these attributes to "anchor" or "calibrate" the panel. Indeed, it is important to have all judges on the panel rate a given attribute in the same way across the beers. Each sensory concept, whether diacetyl, skunky, dry hop, or bitterness, must be clear to all the judges on the panel.
- Once the scorecard (list of attributes) is finalized, judges are trained to rate the intensity of these attributes with representative samples for the category. This can take weeks, because the panel evaluation must be consistent and reproducible before the judges carry out the actual descriptive analysis.
- When they are ready, judges evaluate the beers in the category for all the attributes, usually in duplicate or triplicate. The data is analyzed using complex statistics such as analysis of variance or multivariate statistics.
So why do you need to know all this? Because you can carry out your own informal descriptive analysis on the beers you brew, alone or with your friends, for comparison and quality assurance purposes.
A World of Flavors
First, familiarize yourself with the Beer Flavor Wheel, developed jointly by British and American brewing scientists in the late '70s. The Flavor Wheel (the mother of all wheels, don't let those wine people tell you otherwise) is a fairly good compilation of flavor attributes typically found in beer. It will help you put words to the sensations you perceive when you taste beer.
Now, if you are not familiar with some of the characteristics in the wheel, no need to panic. The Beer Attributes table is a list of typical beer sensory attributes and their definitions. The Beers Standards table tells how to prepare reference standards for them. Most standards can be prepared by spiking a base beer with the item representative of the attribute (e.g., butter extract for the diacetyl/buttery character).
Buy a case of neutral, clean domestic lager beer to serve as the base beer, and add the items shown in the Beer Standards table. When you taste these standards, you conceptualize the attributes they demonstrate by "abstraction" and/or "generalization."
This exercise is called "concept formation" in psychology. If you taste a standard consisting of the base beer spiked with a particular compound or item (e.g., butter extract for the diacetyl flavor note), you develop the diacetyl concept in your mind by "generalization." In some instances, however, it is difficult to find an item or substance that will adequately illustrate the sensory attribute. You must then find a commercial beer with the attribute. The commercial beer is contrasted with the base beer, which should be devoid of the attribute. By tasting both beers you then form the concept in your mind by "abstraction."
You are now ready to do some serious descriptive work. To practice, take commercial (preferably microbrewed) beers apart and identify and quantify their sensory attributes. Train yourself to recognize all the key sensory attributes of beer by tasting as many beers as possible (not at the same sitting!).
A Simple Tasting Method
By the way, how should you "taste" beer? I recommend doing it at a "typical" serving temperature (warmer for ales than for lagers), in a wine glass (the concave shape retains volatiles better), four to six beers at a time, with water and crackers close by to cleanse your palate, and with rest between samples.
- Observe the beer first. Check its color, clarity, and foam structure and stability.
- Smell the beer. Take brief sniffs (the CO2 can hit you rather hard, so avoid big, long whiffs) and concentrate! This is the step when most of the sensory information is collected. That's because the most important (and telling) characteristics of beer are olfactory notes.
- You can now taste the beer. Take a large enough sip. No need to swirl and swish the stuff around. Yes, you should swallow the beer. The taste buds (properly called taste papillae) at the back of your tongue are sensitive to bitterness, so you won't get the full bitterness in a beer unless you swallow it (and flush those papillae in the process). Also, trying to expectorate beer can be embarrassing (it gushes). And with a third of the alcohol of wine, beer does not get to you as quickly as wine does. But in time it will, so consume limited amounts when you taste and do a lot of sniffing.
What It Means
How are you going to use the information you collect when you taste your beers? Well, you must be able to relate sensory properties to brewing ingredients and processes. That's why knowledge and understanding of the brewing process is a condition to success.
For example, turbidity usually indicates some microbial presence. In some cases the microorganisms are meant to be there (some microbrewed beers with culture yeast sedimented
at the bottom of the bottle, for instance), but most often turbidity means the beer is contaminated. And if you can see the contamination, the beer is long gone. Indeed, you can usually smell a problem before you can see it.
- A phenolic (medicinal) smell in your beer means your yeast contains so-called wild (undesirable) yeast. Any of that yeast in your homebrewery should be discarded and replaced (unless you want to make German-style wheat beer).
- A sour taste or a lactic flavor typically warns of a contamination by lactic acid bacteria. If that happens, your yeast and/or your brewing process need some serious sanitation.
- An oxidized flavor signals problems with the bottling process (too much air was let in). Leave some yeast and sugar in the beer when you bottle (for a second fermentation) and the yeast will act as an oxygen scavenger.
The bitterness of your brews depends not only on how much hops you add to the boiling wort, but also which varieties of hops and how old they are. With time, hops get oxidized and lose some of their bittering power.
The head of foam on your beer is a function of the mashing process. Proteins from the grain's endosperm (the white center) and phenols from the grain's husk, which are extracted during mashing, are involved in foam formation and head retention.
And the list goes on... You can expand it by reading about brewing science and learning the biochemistry and microbiology of the brewing process. Three good books to try are Brewing by Michael J. Lewis (Chapman and Hall), Evaluating Beer (Brewers Publications), and Malting and Brewing Science, Volumes I and II by Briggs, Hough, Stevens, and Young (Chapman and Hall). The key is to be able to relate as many sensory attributes as possible to the ingredients and processes used to brew your beers. You want to reach the point where all you need for quality control purposes are your eyes, nose, and taste buds.
Now remember that beer does not age well. Microbial contaminants and oxygen are the two worst enemies of the brewer, especially the homebrewer who has few resources when it comes to controlling these two factors. (Don't take it personally, that's what makes homebrewing a real challenge.) Both contaminants and oxygen result in off-flavors in beer. The longer you wait to drink a contaminated or oxidized beer, the worse the off-flavors get! So don't take chances, and drink it while you can.
Jean-Xavier Guinard is an assistant professor in the Department of Food Science and Technology at the University of California, Davis. He is a sensory scientist with a strong interest in beer and brewing. He is the author of Lambic (Classic Beer Styles Series, Brewers Publications).