Sunday, July 7, 2013

An experiment of open fermentation!

Near the end of May of this year, two of the brewers at the brewery that I worked at, Saugatuck Brewing Company, decided to do some experimentation with wort. The wort was pulled from a beer that was brewed called “The Applause” or other wise known as “The Clap.” This beer was pitched with a wild yeast strain that was pulled from grapes that were picked from Fenn Valley Winery. After the yeast was pitched, there was extra wort after the beer was put into 5-gallon buckets and left to open ferment inside the brewery (the experiment that I reference). 
After only a just a few days a krausen developed on the wort, a sign of fermentation. To keep from infecting other beers in the brewery, the buckets were placed outside, under cover so that rain would not enter the buckets. On this past Thursday, these buckets were retrieved to see how they progressed. The first observable effect of open fermentation was that there were a lot of fruit flies (dead) and fruit fly larvae in the buckets. I decided to smell it and it had a very wonderful tart aroma to the beer. I hurried to find a cup to sample, while the other two brewers decided what to do. The taste was almost as amazing as the smell (minus the fact that I was drinking fly larvae with the now beer). A gravity reading was taken on the beer and it has a ABV of 5.5%. The beer was filtered through some cheese cloth into another bucket.

Later in the evening, I took one of the buckets and gathered some yeast to propagate. I took a sample in a plastic cup, because I didn't have any other vessel to gather it in. I took it home that night and put it into the refrigerator to deal with the next morning. 
The next morning, I pulled the yeast sample out of the refrigerator to warm it up a bit. I prepared a starter out of 200 grams of dry malt extract (DME) and 500 mL of water (to create a 1.040 specific gravity solution). I boiled the solution for a couple minutes and cooled it as quickly that I possibly could. While the starter was boiling, I used a spoon to scoop out as many dead fruit flies and larvae out of the yeast sample that I could. I poured the starter solution into a per-sanitized 1.9 liter growler, after-which I added the yeast to the growler. I put a bung on the growler and shook it up to oxygenate it as best that I could. I then added a airlock to the bung.
It will be interesting to see how this progresses. I will tempt to build this sample up more, by, decanting the liquid and adding more DME solution to it. Eventually I would love to make build a beer with this yeast!


  1. How did this experiment turn out?

  2. It was transferred to another container to get rid of the fruit fly larvae. We haven't done much with it. I kept the yeast and am in the process of building it up. We hope to inoculate other beer with the wild yeast and I am planning on doing a homebrew with the yeast as well.