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Wednesday, February 16, 2011

New Blog: Beer Sensory Science

Back in November, I got an email from a new blogger who's work greatly interested me. The site is called Beer Sensory Science, and the "Beer Sensor" describes himself (I think it's a he) as a "sensory panel administrator at a regional American craft brewery." (For the sake of his employer, he's trying to stay anonymous.) The blog is focused on the nexus between science and the experience of consuming beer, a little-discussed, little-understood element of beer.

So, you get a description of the six most prevalent esters that contribute flavor in beer, such as:
Ethyl butyrate (aka ethyl butanoate): very common in beers. Threshold: 400ppb. Common levels in beer: 50-250ppb. Smells of tropical fruit, pineapple, Juicy Fruit bubble gum. Our panel has seen ethyl butyrate in: Alaskan Winter Ale, Hair of the Dog Blue Dot, Stone Levitation, Coors Blue Moon, Deschutes Twilight, Stone Belgian IPA.
Or this post, on the person-by-person variability of olfaction:

Some practical examples of this have been seen in the threshold tests I’ve performed with the panel regarding diacetyl. Some panelist’s thresholds are down below 30ppb, while others are well over 100ppb, and there are even 1 or 2 who may be totally anosmic to it (meaning they have no ability to detect it at any concentration).... Another example comes from the flavor standard “indole”, which has been known to elicit a floral jasmine-like aroma for a certain portion of the population, while the rest of the population smells fecal material.

Or this post on glycosides, currently my fave:

Glycosides are compounds which contain two parts: a sugar component which is in its cyclic (ring) form, and another component attached to the sugar at the number 1 (or “glycosidic” carbon). Some of these companion molecules can also be sugars, so sucrose, being a 2-sugar molecule (disaccharide) made of one glucose unit and one fructose unit attached through the appropriate carbon, is an example of one of these types of glycosides. The glycosides which appear to influence beer flavor are found in hops and have aromatic compounds bonded to the carbohydrates. In their combined state, the glycosides have no flavor; no sweetness and no aroma. However, once this glycosidic bond is broken the aromatic compound is free to volatilize into the headspace of the beer and ultimately into your nose.

Fascinating! Of course, since the Beer Sensor is a chemist, you get baffling information like this, too: "In beer, the substrates that react to form the variety of common esters are the numerous alcohols present (byproducts of amino acid and carbohydrate metabolism) and the various acyl coenzyme A molecules which are active participants in some of the metabolic processes of brewer’s yeast." Err, right.

In any case, it's a great site and one I'll be checking in on regularly. Have a look.

1 comment:

  1. Jeff, here's a related article out of the latest Scientific American. Thought it was interesting.