Sensory Evaluation is a common method of evaluating beer. Unlike other testing methods, which make use of various instruments and equipment, sensory evaluation is conducted by individuals and relies on their sensory perception. This evaluation can be used to assess such subtle aspects of beer as freshness, quality, craftsmanship, balance, conformity to style or brand, and drinkability.
During sensory evaluation, there are four different aspects of beer that come under scrutiny: appearance, aroma, flavor, and mouthfeel. The assessment of a beer’s appearance includes notes on its color, which can range from a light straw to black; its clarity, which can be transparent, veiled, cloudy, or opaque; and its foam. Various aspects of the foam are observed, including thickness, color, texture, and retention (how quickly it collapses), as well as the lacing that forms on the inside walls of the glass as the beer is consumed.
When evaluating aroma, there is a wide range of features presented for evaluation. Because beer is made from a minimum of four ingredients, and each of these ingredients can contribute a range of aromas, this often results in a very complex nose. Common descriptors used to characterize a beer’s aroma include grain, bread crust, caramel, toffee, molasses, chocolate, coffee, clove, coriander, pepper, grassy, banana, raisin, plum, grapefruit, pine, herbal, earthy, resinous, even “sweaty horse blanket” for some specialty beers such as gueuze. There are also brewing faults that can be detected in the aroma. Some examples include notes of corn, butterscotch, skunk, sulfur, vinegar, chemicals, or plastic.
The flavor of beer combines its taste and its aromas and is equally complex. It is also during this stage of evaluation that bitterness is first perceived. Because bitterness is most readily perceived at the back of the tongue and finish is an important aspect of beer, it is common practice to swallow beer during sensory evaluation in order to better assess these elements. Other taste sensations are often described as malty, sweet, sour, citrus, or acidic. Defects often reveal themselves as imparting flavors of wet cardboard, cat urine, mold, leather, vegetable, rancidity, metal, or astringency.
The final aspect of sensory evaluation, mouthfeel, relates to the texture of the beer. Notes are taken on its weight and body as well as other possible sensations such as warmth, astringency, or slickness. Carbonation levels and carbonation texture also play an important role in the mouthfeel of a beer.
Although sensory evaluation is not as objective or precise as some laboratory tests, which can yield numerical results, it is still often used in breweries, either on its own or as a complement to these other methods because it better reflects the consumer’s experience of the beer. Most brewers will taste their beers regularly, at various stages of the brewing process. In addition to this, many breweries have a quality control department, which will conduct sensory evaluation sessions in order to get a wider range of feedback.
There are a number of tools that can be used to assist in the sensory evaluation of beer. The most common of these tools is a beer evaluation sheet. There are many different styles of beer evaluation sheets, but most of them will provide guidelines for features a taster should look for and comment on while assessing beer. Another common tool is the Beer Flavor Wheel. Developed by Morton Meilgaard in the 1970s, the Beer Flavor Wheel provides a wide range of beer descriptors. These are divided first into those perceived by sense of taste and those perceived in the aroma. The descriptors are then organized into 14 categories, each of which contains between one and six descriptors. Meilgaard’s aim in creating this wheel was to establish a standard vocabulary for beer evaluation and to this day many organizations use his Beer Flavor Wheel as a reference tool.
No matter how many tools and guidelines are used, sensory evaluation can never be fully objective. Factors such as the taster’s diet, mood, experience, and personal preference, the tasting environment, and the time of day, as well as the sequence in which beers are served can all affect how a beer is perceived.
Brewers Publications, ed. Evaluating beer. Boulder, CO: Brewers Publications, 1993.