A few weeks ago I wanted to explore a pale ale that I hadn’t brewed before. I decided to take it easy on myself and get the recipe from Brew Your Own’s 150 Classic Clone Recipes edition, and I settled on a steam beer. Technically I can’t brew a steam beer because I have a direct-fired kettle, but I’ve never been one to let details get in the way of a brew day.
Pretty straightforward ingredients: pale malt, crystal malt, and one hop in three additions. But then there’s a yeast I’ve never used before, California Lager, and there’s the relatively high fermentation temperature (for a lager yeast) of 64 degrees.
My OG and volume were almost spot-on at 1.052 and 11 gallons, respectively. I let the temperature of the wort stabilize overnight at around 66 degrees before oxygenating and pitching the yeast starter, which had been been on the stir plate for about two days before I let it settle overnight. Signs of fermentation were obvious 12 hours later, at which point I moved them into a freezer set to 64 degrees.
I did a forced ferment test on this batch, pouring off some of each carboy into an Erlenmeyer flask and setting on the stir plate, unrefrigerated. When I checked the gravity after a few days at 80 degrees, it was only down to 1.018, which is far above the expected final gravity. I wasn’t sure what to think of that.
The bubbles that form on top of the fermenting wort never went away, even weeks after fermentation started. I let the temp come up to 68 over the course of the third week, but still the bubbles remained. Finally I racked into serving kegs today and was able to conveniently check the gravities. One carboy, the one whose bubbles were the “stickiest” and most abundant, was still around 1.018. That half of the batch was also very clear. The other carboy was around 1.014, and had a cloudier appearance.
Sampling at different points in the transfer process might have made a difference in clarity, but I wouldn’t expect it to make a difference in attenuation. Why did the same batch of yeast starter and the same wort produce two different beers?