May 202119Wed

Yeti’s almost ready!

SG 1.016 19.6℃ cold-crashing

I’m unsure about bottling this today as planned because there are some weird things going on with the fermentation that I’ve not seen before.

The bulk of fermentation activity seems to have slowed around 9 May to the point where there isn’t enough heat being produced to trip the ferment fridge into action, and temperature has been fluctuating gently very near to room temperature, which for the most part was around 19℃.

Yeti Imperial Stout, 15 days into Primary

Then something happened on 17 May which caused a sufficient temperature increase to trigger the cooler, which was set at 19℃ with a 1℃ ± threshold, so cooling starts at 20 and heating starts at 18℃. The gravity has also been bouncing up and down since then but I suspect that’s more due to the variations in temperature.

The question is, what’s causing the temperature to rise and trigger the cooler, three times in two days? There’s also some occasional airlock activity each time I open the door, as if fermentation is still underway. I can’t believe that’s the case after such a long period of stable gravity, and I don’t want to leave it too much longer, basically because I want to use my fridge for another brew, so I’m hoping that the worst-case scenario is over-carbonated beer and not an infection of some kind.

Having taken a gravity sample just now (and naturally a cheeky taste) I’m fairly confident there’s no infection – in fact it tastes bloomin’ lovely! Gravity looks to be 1.016 which makes for 7.5% ABV. Not quite the 9.7% I was hoping for, but still fairly respectable.

Instead of bottling it today I’m going to cold-crash it for a couple of days, just to see what I can convince to drop out. Bag Thing fitted, dials set to 4℃.