Wednesday, November 7, 2007

Addition by Subtraction

Ever since I have been doing 10 gallon batches of home brew I have been splitting each batch into two equal-sized partitions. In doing this, I can use two different yeast strains on the same recipe and compare the final results.

Almost 5 weeks ago I brewed what is termed a "heather ale". This is a historical Scottish style of beer in which heather tips are used in place of hops. The use of hops in brewing is a relatively recent development in the grand history of beer. Some even say the first beer contained heather.

Problem: I had neglected to rack this beer to a secondary fermenter for far too long. I kept putting it off. I like to time my brewing so that I can syphon a week-old beer off of the yeast (and into the secondary fermenter) and immediately syphon a freshly brewed beer on to the yeast cake. I had planned to ferment an imperial milk stout on the yeast cakes of the heather ale, but I could never make the time, didn't have the equipment, etc.

Yesterday, I gave up on reusing this yeast. I decided I would just rack the beer into secondary and pitch some fresh yeast when I brew the imperial milk stout. I didn't want to risk off-flavors associated with leaving the beer on the yeast for an extended period of time.

The two yeast strains I used were White Labs Irish Ale Yeast (WLP004) and Wyeast Scottish Ale Yeast (1728). I began to siphon the beer off the Irish Ale yeast, I took a sample for taste and to take the final gravity reading (it was 1.010). Tasted great, no off-flavors. Had a delightfully smooth and creamy mouthfeel with a finish that is both biscuity and flowery.

Then I did the same for the beer on the Scottish Ale yeast....

Something was wrong, the aroma was sour. I took my sample out and continued to siphon the beer into the secondary fermenter. Once I was finished I sat down and tasted it. It smelled of sweet vinegar and cherries! The taste was tart and sour with a touch of sweetness. The beer is contaminated with some sort of organism. Which one it is, I'm not sure. The taste is very similar to that of Flemish-style sour ales such as Verhaeghe Duchesse De Bourgogne.

I'm trying to figure out how half the batch became contaminated. This little mistake will still be bottled and aged (possibly on oak chips), I'll probably enter this happy accident into some home brew competitions as a Flanders red and see how it fairs.

Here are the front and back labels I cooked up for the heather ale. I used a picture my friend over at We Are Cartographers took of my traversing Holyrood park in Edinburgh, Scotland.

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