Thursday, August 12, 2010

Beer Stats!

Extremely unmanly of me is the fact that I don't really find sports statistics interesting. Sports stats are a common default male conversation for which I usually have nothing to contribute. However, I do enjoy watching sports, and by sports I mean hockey, provided I am consuming beer. Next time I'm at the pub enjoying a nice india pale ale and someone starts on about Crosby vs Ovechkin giving me an earful of numbers, I think I'll try to switch the conversation to numbers that really matter: Beer stats. Your pint vs mine.


To many drinkers, this is the only number that matters, the higher the number the less you need to consume to feel the effects of the ethanol produced from the fermentation process. Alcohol/volume (abv) is a worldwide standard and is usually the only beer stat you can find on the container. It is simply the amount of ethanol expressed as a percentage of volume. Conventionally brewed beer, using a conventional yeast and a single fermentation step is in the 2% to 12% abv range (almost always in the 4-6% range). Higher alcohol content can be achieved using alcohol tolerant yeast strains, adding sugar during fermentation and by fractional freezing that produces so called ice beers. The process of fractional freezing involves cooling the fermenting liquid until ice crystals float to the surface then removed. This process removes water thus increasing the ratio of ethanol to water and therefore increases the abv. If you really want the Sidney Crosby of beer abv you could try a $800 bottle of The End of History by Brew Dog. Maximum Ice (7.5% abv) drinkers will be impressed with The End of History's 55% abv.

Degrees Plato
The coolest sounding statistic, degrees Plato, unfortunately isn't very useful when comparing pints you are drinking as it is mostly a stat useful during the brewing process to determine the final abv. Degrees Plato is the %w/w sugar ie the grams of sugar per 100g of wort. Since sugars are consumed and converted to ethanol during fermentation, and thus not what was origonally put into the wort, the determination of degrees Plato of beer is usually determined using measurements of specific gravity. Specific gravity is the ratio of the density of the wort or beer to the density of water. Specific gravity is used instead of direct density measurements as at a standard temperature and pressure specific gravity is more easily measured using an instrument such as a hydrometer. The difference in specific gravity between the starting wort and the finished beer can be used to calculate the ethanol produced during fermentation since decreased dissolved sugar and increased alcohol decreases the specific gravity.

Standard Reference Method
This is a quantification of beer colour. The standard refernce method (SRM) is 12.7 times the absorbance of filtered beer at 430nm. So the SRM is really only measuring "darkness" and not truly colour and it looses linearity at higher SRMs. There is a highly related system EBC which also uses an absorbance measurement at 430nm, and I'm unsure of which is in more common usage in Canada. There are some other more sophisticate systems to better quantify colour of beer. For example Tristimulus colour is determined by measurements at many different wavelengths and describe beer colour in a three dimensional colour space.
This is an especially cool stat for those that like uber dark beers. Nothing like bragging about your pint of Guiness with an impressive SRM of 40, until some guy with an Imperial Stout reminds you that his pint has an SRM of 70.

International bitterness units
Hops are added to beer as a flavouring and stability agent. Interestingly from kamel:
Incidentally, the hop alpha-acids also have antibacterial and anti-inflammatory properties. Thats why traditional India Pale Ales (not that Keith's crap) have a strong bitter, hop taste. Extra hops were added to help preserve the beer on its journey from Britain to India.
The determination of international bitterness units (IBUs) involves extraction of the bitter tasting hop alpha-acids and quantification using UV absorbance or HPLC. Since this involves sophisticated laboratory equipment there are alternative methods for the small scale or craft brewery. One involves adding hop alpha-acids to a beer of known IBUs, like Bud, until it has the same bitterness as the beer in question. While this method has the benefit of drinking lots of beer for replicate samples, it, and the IBU measurement itself, suffer from a disconnect between IBUs and perceived bitterness. Malty beers with the same IBU as a pale ale will be taste less bitter.

While I haven't seen quantification of beer carbonation, in beverages it is reported in grams/litre and can be determined by infrared absorption at 4.27 um. Such a stat would obviously only refer to an untapped keg or unopened bottle/can. Some beers are nitrogenated instead of carbonated, usually stouts and British ales. Again I have not seen a beer report an amount of nitrogenation, however this would be a useful and descriptive statistic.

More Stats
Kamel's great post about beer foam entitled, Good Head has some information on the composition of beer head. The denatured protein LTP1 is the main structural component of the head along with hop alpha-acids. This reeks of a need for quantification. This information along with carbonation/nitrogenation content would inform the drinker on proper pouring to ensure the best possible head.

Inspiration for this post was from discovering this very useful quantification of beer greatness as my current favourite beer, Tree Breweries Hop Head, prominently displays the fact that it measures 45 IBUs. I'm also enjoying Phillips Hop Circle IPA however I don't know it's IBU. This is unfortunate as I think beer stats are a great opportunity for brewers, especially craft brewers to advertise and quantify their uniqueness. Beer geeks want to know! Yes this might lead to more of the ridiculousness exemplified by Maximum Ice, and I would also say that there is a subjective quality to beer that perhaps would get lost in the numbers. But sports statistics are popular and sports geeks know that just like Ovechkin looks better on paper, Crosby's the real winner.


Kamel said...

Nice post. I do try to take note of the beer stats when they're available, in particular IBUs since I'm particularly fond of a bitter, hoppy beer. Some recent ones I've had are 21st Amendment Brew Free or Die IPA (7.0% ABV, 70 IBU) and the Dogfish Head 60 minute IPA (6.0%, 60 IBU). Dogfish head also does a limited edition 120 minute IPA that weighs in at a whopping 18%, 120 IBU! More locally, I had the pleasure of drinking HopCity's Barking Squirrel last week, but no numbers on that one.

I think having those kind of stats readily available (other than ABV of course) tends to be the sign of a craft brewer, since they know they're catering to a particular clientele.

Now I'm thirsty.