By Kate Prengaman
From a dark, malty stout to a bitter pale ale, there are a lot of flavors to taste in beer. But, it can be hard to understand and appreciate these flavors unless you understand the science of how we taste.
“We tend to be somewhat oblivious,” Jon Roll said during a presentation at the first Wisconsin Science Festival in September. A University of Wisconsin professor of Bacteriology, Roll teaches classes in beer brewing. By learning about taste, he said, “I became much more aware of things I was not aware of before. I had more appreciation of the differences.”
Roll’s presentation at the science festival was built around a beer tasting that drew 40 participants interested in the science of tasting (and, of course, drinking beer). They sat down in front of trays full of labeled little white cups, filled with mysterious liquids that were definitely not beer.
Roll explained the basics of the taste tests on everyone’s plates. The tongue only tastes the five primary flavors; sweet, salty, sour, bitter, and umami. Umami is the savory flavor, found in things like soup broth, cheese, and MSG. All the other complexities of what we call “taste” is really aromatics, we taste through smell.
When the tongue tastes something, it is really working to detect the nutritional value of potential foods, according to a recent paper published in Science. The sweet and umami flavors cue us into energy and protein rich foods, so we find these tastes very appetizing. Strong bitter or sour flavors can indicate poisonous or spoiled foods. We typically dislike these. The brain does most of this food analysis subconsciously.
“Many of your senses work together, one affects the others subconsciously,” said Jeff Sindelar, a meat specialist at UW.
At the science festival, Sindelar explained that people often associate the taste of juicy meat with a tender texture. However, tests show that juiciness and tenderness are not related, we just associate them subconsciously.
The class tried to taste consciously. They drank salty water, sour water and a bitter brewed tea, trying to feel on their tongues which region of taste buds was responding to each stimulus. They nibbled bitter and sweet chocolates. Noses pinched closed, they rubbed gum drops against their tongues. Without the sense of smell to provide a hint or cinnamon or mint, the tongue just tasted the sugar. These simple tests are just the beginning of complex taste training that beer experts go through.
This ability to do and understand this type sensory analysis is very important for brewers, Roll explained. There are common problems in the brewing process that can create a variety of “off-flavors” in the beer. To go back in the process a fix the mistake, brewers have to know what chemical compound is creating the off-flavor. They train themselves to identify these compounds by drinking beer purposely spiked with a common chemical culprit, so they form conscious associations between off-flavors and specific chemicals.
To track down how a certain chemical appeared in the beer, the students in Roll’s brewing class do a lot of scientific sleuthing. This way, they understand how to alter the brewing to prevent the off-flavors. At this point, he explains, human taste is still the most sensitive instrument we have for detecting trace amounts of certain things in our food and drink.
When the class finally turned their sense of taste onto some beer samples, they sipped carefully; trying to detect the subtleties of flavor. Joe Pulizzano, a professional brewer, explained that good beer has a progression of flavors. For him, the fun of brewing is in the science of creating complexity.
“My favorite is a porter, I make it complex. I like a thick beer, well balanced, with a progression of aromas; caramel, burnt, and coffee.”