Wednesday, June 20, 2007

Le Salon de MitMoi IV: Beer "The Test"

Would you/could you discuss the correlation between pure water for brewing vs water quality in our watershed?

The Burton Water Example

The Burton area in England is noted for producing pale ales and IPAs (such as Bass). The water in this region is very hard, resulting from the prevalence of gypsum minerals. Normally we think of hardness values around 100 as moderately hard, and values as high as 200 as hard. The hardness in Burton waters is off the scale in comparison, and is typically over 800 mg/L as CaCO3. Because gypsum is the dominant mineral, these waters are also characterized by sulfate as the dominant anion (rather than bicarbonate). The fact that the birthplace of pale ales and IPAs happened to occur in an area with unique water chemistry has sparked the interest of many brewers, and has led many to conclude that very hard waters rich in sulfates are not just a coincidence, but are essential ingredient in a proper pale ale. The mineral profile of Burton waters is said to both enhance and refine the bitterness of these beers.

If you talk to a brewer that brews a pale ale or IPA, it would not be unusual to find that he or she is aware of this association with Burton water, that they believe that a high hardness associated with sulfate is important to the flavor profile of the beer, and they may even add “Burton Salts” (powdered gypsum) to their pale ales because they are convinced it makes a difference. I know one brewer that is so convinced of the flavor nuances contributed by Burton Salts that he will discuss them at great length, concluding that the sulfate in particular lends a drying finish to the beer. He believes that this dry finish leaves his customers thirsty for another sip, and helps him sell more beer.

When I hear a story like this, I think “Aha! We can formulate a testable hypothesis about the importance of Burton salts on the flavor profile of Pale Ales!” ( . . . have I mentioned that science is another obsession of mine?).

Consider the following experiment: Brew three beers with exactly the same IPA recipe, except that one of the three is brewed with water matching that of Burton (with a hardness of 850 mg/L) and the other two are brewed with local water (here in Syracuse the water hardness tends to be around 110 mg/L). If the minerals in Burton water affect the flavor, then the beer brewed with Burton water should taste different. Simple, right? Comparison of the Burton-batch with the other two batches will determine what those differences are and how important they are. We need two batches brewed without Burton salts to help identify the normal variation between batches. So the Burton batch not only should taste different, but those differences must be greater than the normal batch-to-batch variation between otherwise identical beers, if we are to conclude they are significant.

Serve these beers at your next tasting party and see if anyone can tell them apart (I’m sure you all have regular tasting parties, don’t you?, they’re loads of fun). Of course, to make the comparison meaningful no one can know which beer is which, including the host. Naturally, this leads us to the double-blind triangle test (oh come on, you’ve read this far don’t give up now). Lets say I make these three beers, one of them with Burton water, and label them with three random labels (lets say Larry, Curley, and Moe). At this point I know which of these three beers is the Burton beer, but I don’t tell anyone else at the tasting. Next, I have one of the guests replace my labels (Larry, Curley, and Moe) with different labels also selected randomly (such as Red, Blue, Green, or whatever), and pour them into three glasses for each guest, which are also labeled Red, Blue, and Green. The test is now double blind and no one knows which beer is which. The rest of the test is simple - everyone tastes all three beers and determines which beer they think is most different from the other two and why. Selections are made on an anonymous ballet without discussion. After everyone has made a selection, we compare labels to find which beer is which, and count how many people choose each beer. If there are no differences between the three, you’d expect that random chance would result in 33% of the participants picking the right beer as being different. If the Burton beer really tasted differently, significantly more than 33% of the participants would have to identify it as the one that is different.

I’ve conducted this experiment twice, the first time with 35 participants and the second time with 12. Both times people could not identify the beer brewed with treated water more often than dictated by chance. From these results I conclude that Burtonized water is not really as important as is commonly believed.

Experiments are also planned to test the importance of regional water chemistries on the characteristics of stouts in Dublin, and pilsners in Pilsen, among others.

Just to be clear, these results do not mean that water chemistry isn't important. There are many ways in which water chemistry can create problems. Some examples:

  • Water with too high a pH (especially if buffered by high alkalinity) can create problems in the mash, including poor enzyme activity, and extraction of harsh tannins from the barley husks. It is possible that moderately high alkalinity may be alleviated by using more heavily roasted grains (this is the point that will be followed up in the Dublin water experiment).
  • Water high in iron and sulfide (sometimes this is a problem with well water in particular) is likely to produce off flavors in the finished beer.
  • Chlorination in municipal tap water can often create detectable off-flavors in a finished beer.

My own precautions against all of these issues is to use a clean, reliable potable water source, monitor the pH of the mash and runoff during the sparge, and remove chlorine by carbon filtration.

Um, what was the question again?

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