Judging Beer Aroma and Flavor

One of the most challenging aspects of beer judging is assessing aroma and flavor. Appearance is relatively easy. A description of color (light straw, golden amber, copper, ruby, chestnut brown, walnut brown, nearly black, or ebony), clarity (clear, slightly hazy, cloudy), followed by a description of head (thick and chunky, tan and creamy, thin veil that dissipates quickly), and lacing (no lace, intricate patterns, spidery, spotty, distinct lines with each sip, or long legs) can be verbalized and observed. A table of six people could all look at the beer and agree with the appearance.

Aroma and gustation are more subtle. These are chemical in nature, making them much more difficult to interpret. Human beings have the ability to distinguish at least 10,000 distinctly different smells. In research on Scent and Fragrances, [Springer-Verlag, Berlin Heidelberg, 1994], G. Ohloff stated, “The olfactory sense is able to distinguish among a practically infinite number of chemical compounds at very low concentrations.” With this in mind, the ability of beer judges to detect and describe the same profiles in beer seems virtually impossible.

How we perceive smell

The olfactory nerve detects the aroma, translates it into nerve impulses, and transmits it to the olfactory bulb within the brain. The brain records those impulses and assigns a description to what it interprets as a particular aroma. Unfortunately, the impulses of intensity and the translation performed by each human brain enter the realm of ambiguity when interpreted. One person may describe a phenolic aroma as clove-like, while another describes it as hot-and-spicy. A third may describe the same odor as smoky. Their olfactory nerves may be picking up these aromas at differing rates; depending on the structure and concentration of nerves, they may also pick them up in different intensities. This is easy enough to understand – some of us have thick hair, others have no hair; some have perfect vision, while others need glasses. The same is true of the system that governs the complex olfactory structure. Some people cannot detect diacetyl, described by many as popcorn butter, butterscotch, or rancid grease.

The olfactory system also includes our largest cranial nerve, known as the trigeminal nerve. This nerve interprets sensations in the face, teeth, mouth and scalp, and governs the motor process for the “chewing” muscles. Trigeminal sensations of cold (found in menthol in low to moderate concentrations), heat (menthol in high concentrations), irritation (chlorine gas), burning (hot chili powder or mace), tingling (whisky or vodka), or other vibes that cause muscular response are found in conjunction with 70% of odor stimulation.

In addition to this intangible interpretation of aroma, the human olfactory sense undergoes a phenomenon called adaptation. After constant stimulation of a volatile compound, the receptors in the nose become accustomed to the aroma, and perception is dramatically diminished. Studies indicate this can occur in the amount of time it takes to chew and swallow one mouthful of food. Aromas that mask others can also alter how they are perceived – aromas such as perfume, freshly brewed coffee, newly painted surfaces, or fumes from passing traffic.

How we perceive flavor

Although the theory of tongue-mapping has persisted within many ranks of sensory specialists, newer theories suggest that the tongue, the soft palate, and the epithelium of the pharynx and epiglottis are able to detect a “continuum of percepts similar to color vision.” Past interpretations of research suggested that we detect sweet, salty, sour, bitter and umami sensations on specific areas of the tongue in greater and lesser degrees. Newer research includes the fatty acids (linoleic acid), metallic sensations (blood), spiciness (black pepper), and astringency (tannins), while also expanding the sensation of taste to include aroma, texture, and temperature.

Perception and intensity of taste can be affected by many factors including: genetic make-up, hormonal levels, aging, zinc deficiency, medication, temperature within the oral cavity, diminished olfaction due to colds or allergies, tumors on the temporal lobe, and neurological impairment due to illness or disease.

Although Japanese researchers include “kokumi” or the sensation of mouthfeel as a component of taste, beer judges assess this as a separate category. Since mouthfeel is more mechanical and chemical, it seems easier to interpret than those two sensations - aroma and flavor - that are strictly based on chemistry. Mouthfeel is a feeling of thinness, thickness, or dryness. It includes effervescence that dances across the tongue, slickness, cloying sweetness, alcoholic warmth, a quick finish or long, lingering aftertaste.

Although all these factors can be assessed individually, the overall impression that results from the smooth blending of these complex profiles may be the difference between technically correct and world class.