Residual Sweetness

Last night we bottled the Mow Cop Stout. It’s a long-winded process – it took two of us practically all evening to bottle and label the beer. But they do look rather good, if I say so myself!

We tasted the stout, and whilst it has not conditioned yet we could get a reasonable idea what it will be like. Surprisingly like Guinness actually – with that rich dark burnt flavour left in the mouth that you’d expect.

What surprised us though was the sweetness, or lack of it. The fermentation finished at a rather high final gravity of 1.021, which means there is a lot of unfermented “residual sugars” left behind by the yeast. This is caused by the types of sugars present in the beer. If there are a lot of large, complex, unfermentable sugars then you end up with a high final gravity (and associated lower alcohol content). And generally you’d expect the beer to taste sweet, which is great for some styles. We thought we were going to make a sweet stout (rather than a dry stout like Guinness), but in fact the sweetness and body was surprisingly like Guinness.

Why? Well I understand that it really does depend on what sort of unfermentable sugars are left in your beer. Some taste sweeter than others. In our case, the hydrometer tells us there are a lot of residual sugars, but our tongues do not. No matter – we’ve high hopes that it will be a lovely brew.