The Journal of the American Society of Brewing Chemists rarely fails to be a highly entertaining read, and the latest issue is no exception. Most of the articles are far too technical for the layman to grok; Microkhan’s eyes certainly glaze over at the mere mention of “alpha-acids isomerization yield”. But the issue’s lead piece, by a quintet of Japanese researchers working for both Niigata University and Sapporo Breweries, is nothing short of pure genius.
The researchers set out to measure, with amazing precision, the strength required to swallow various types of beer. Their test subjects were a lucky bunch, assuming they didn’t mind all the electrodes connected to their gullets:
The sensation in the throat while drinking is important for beer. To evaluate this feeling, we developed a noninvasive biometric system for measurement of the swallowing motion while drinking. The system measures movement of the Adam’s apple and provides an electromyogram (EMG) of the throat musculature and swallowing sounds by simultaneously employing pressure sensors, EMG electrodes, and microphones, all mounted on the throat surface. As analytic parameters, we used the period of larynx heave, throat muscular activity, and intervals of swallowing sound.
Their conclusion? Brewers should strive for beers that produce a “short laryngeal movement time.” Obviously.
minderbender // Apr 3, 2009 at 1:06 pm
If it helps, alpha acids are the predominant source of bitterness in beer. Different varieties (and crops) of hops contain different percentages of alpha acids. However, alpha acids are not water soluble, so it is necessary to “isomerize” them by boiling them in the wort (the solution of water and malted barley that becomes beer once yeast is added).
So if I had to guess, I’d say that “alpha-acids isomerization yield” has to do with the final concentration of alpha acids in the wort (and hence the beer), depending on the form in which hops or hop extract is added. There has been a shortage of hops recently, so I’m guessing brewers care a lot about getting a high yield.
Brendan I. Koerner // Apr 3, 2009 at 1:09 pm
@minderbender: Thank you so much for the skinny on alpha acids. Getting learned comments such as this really brightens my day.
I’ve read a lot about the hops shortage, but haven’t really seen much of an impact on retail prices. I guess brewers have their ways of making do with fewer choice ingredients. The wonders of chemistry…
Jordan // Apr 4, 2009 at 12:44 pm
One of my favorite research articles ever is an archeology/analytical chemistry paper about 3000 year-old pottery and bronze vessels form China that had been used to hold alcohol. Most interesting was that the bronze vessels had corroded in such a way that their contents were hermetically sealed. If you read the paper carefully, at one point the authors admit that they tried some of that ancient booze.
Best. Bar story. Ever.
http://www.pnas.org/content/101/51/17593.abstract?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=wine&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT (Requires PNAS access for the full text)
Brendan I. Koerner // Apr 4, 2009 at 6:28 pm
I’ve actually got a post skedded that’s along these lines. Pegged to new research re: millet agriculture in neolithic Western China. Stay tuned…