Under fermented, but still tastes good...

[MathMan]

My recent extract brew began at 1.060 and ended at 1.022; I tasted it and it tasted exactly as expected! I went ahead and kegged it but I guess I've just never known exactly why I'm supposed to expect 75%ish attenuation.

So, why is 75% attenuation expected and/or required? Is it just for the alcohol? Or maybe a bit of a taste difference? Thanks in advance!

 

[drathbone]

Higher attenuation would lead to more alcohol and less malt (sugar).

 

[Yooper]

Attenuation is a hard one! You've asked a very hard question, believe it or not!

So many things go into the attenuation you'll actually get from the yeast. Ingredients (beers with lots of crystal malts won't finish as low as beers with more fermentable sugars), yeast strain, temperature, yeast health including pitching rate, mash temperature, etc.

In general, some yeast strains will ferment to a slightly lower FG than others. But in the case of my oatmeal stout, it finishes at 1.020 because of the ingredients and not just the yeast strain.

A good way to predict probable FG is to look at the recipes, ingredients, yeast strain, and so on and come up with your best guess. I have some beers that will give me 65% attenuation, some which will give me 85%! So, it's important to look at the whole picture.

Sometimes beer styles will help- a 1.007 cream ale (which has simple sugars from corn and/or rice) will be good! A 1.007 sweet stout (which should have plenty of residual sweetness from dark malts and lactose) would not!

 

[MathMan]

Well, I'm glad to hear that it isn't an easy answer at least. The beer is a brown ale which takes notes from Abita Turbodog. So, some pale extract and a pound of chocolate malt finished off with Wyeast Irish Ale. Mabel that makes the question easier to answer, maybe not. Thanks for your responses!

 

[MathMan]

Sorry, that's a pound of Crystal 80 and a half pound of Chocolate malt. Still a lot of Chocolate, but not nearly as much as a lb.