Put Diacetyl to Rest
It all started with an IPA. The first sip and I instantly spit it out. It was a buttered popcorn death bomb. Why did this happen? I guess the cold temperature in my home did not agree at all with my yeast. The real punch to the gut happened when I brewed a triple decoction pilsner. I spent an 8 hour brew day and 2.5 months of waiting for what would be the nectar of the gods. Unfortunately it was the return of the “Diacetyl Beast” part II.
Diacetyl can be a serious problem for many brewers. Diacetyl has the flavor of butter or butterscotch. It is a naturally occurring product of yeast fermentation, and healthy yeast will clean up this flavor while fermenting. Bacteria such as pediococcus and some strains of lactobacillus can also create this flavor. Creating a large yeast starter and ensuring proper fermentation temperatures are the best ways to avoid this flavor.
But what can you do if you have already fermented your beverage and the flavor persists? My immediate thought was pitch more yeast. After doing some deep internet searches , I found a process called krausening. Krausening is the same as creating a starter, but pitching the starter in right as it reaches peak fermentation. Seeing as I had two separate beers that needed fixing I decided to try an experiment. For the first starter I used 1118 champagne yeast. I knew this yeast was an absolute powerhouse and could eat through anything. 3 packs of yeast went into a starter. As soon as I saw foam on top I dumped it into my fermenter. For the other batch of butter beer I used US-05 the standard go-to American ale yeast. Two packs in a starter and a few hours later I pitched it into the fermenter. I wrapped both beers in a Fermwrap to keep them warm. and threw a blanket over them.
A week later I cold crashed and put them both on tap. The beer with the 1118 had no trace of diacetyl whatsoever. It was wonderful, but remained cloudy and would not clarify-thanks 1118. The US-05 beer cleared out fairly well for being an IPA. It still had a small amount of diacetyl off flavor, but far far less than when I started. The beer was at least drinkable by my standards. I’d like to experiment with more yeasts to see how they perform.