Originally Posted by sniemeyer
What factors do you use to control the sweetness of your beer?
I assume that any difference between the actual attenuation and the limit of attenuation will increase sweetness, as this indicates the presence of residual unfermented sugars. To increase sweetness in this manner, I assume you would choose a less attenuative yeast that flocculates earlier, thus leaving the fermentation incomplete, or by under-pitching. But this seems like a pretty unpredictable process that would be difficult to get exactly right (for instance if you are trying to hit a specific final gravity).
The other factor commonly mentioned is fermentation temperature. But this is a little confusing, because shouldn't higher fermentation temperatures just increase the percentage of unfermentable vs. fermentable sugars -- i.e. creating a more dextrinous beer? Dextrins, I believe, are not actually sweet; they contribute to the body of the beer, so I am unclear as to why fermentation temperature would influence sweetness, if it actually does so.
A third factor would be the type of malt used. Crystal and Munich, for example, are supposed to contribute sweetness. In what way do they do so? Do they just contribute unfermentable but non-dextrinous sugars? -- i.e. sugars that are perceived as sweet but are not fermentable?
My #1 way to control sweetness is the recipe, next is choice of yeast strain, then mash temp, and finally fermentation conditions. The last two may flip flop.
If I want some residual sweetness in a beer I look to get that from specialty malts (and some from Vienna or Munich). It is difficult to make a beer with much residual sweetness using just pilsner or pale malt, no matter what temperature(s) you mash at. By mashing higher, you can get more oligosaccharides in the wort, but once you get above a 3 sugar chain, they don't taste sweet at all, and most of the shorter chain oligosaccharides are fermentable by yeast. There might be a slight increase in sweetness. By way of analogy, using mash temps to control sweetness
is like using a step stool to clean your gutters. It gets you closer to where you want to be, but not all the way there. Now get yourself a ladder (alter the recipe) and you can get exactly where you want to be. Mash temps are a tool one could use on the job, but there are much better ones to use.
My mash temps are chosen primarily to control mouthfeel/body of the beer. My Kolsch and Helles have almost identical recipes, but I mash them differently (and use different yeast of course). One is light and crisp, the other much fuller in body. I wouldn't consider either one sweet tasting.
As to the choice of yeast, I use one strain of yeast that typically will finish around 1.008 and another strain that likes to finish around 1.014 with a similar recipe, yet the lower OG beers always taste sweeter. I this case I believe this particular yeast is producing a non-fermentable sweet tasting compound. If you want sweetness, use a yeast with a low attentuation.
One can also get yeast to crap out early and give a high FG. One could do this and then force carb to get a sweeter beer. There is the danger of bottle bombs if bottling though.
One question I have, and may address some of the confusion, is how do dextrins affect perceived bitterness? Do they at all? We are all familiar with residual "sugars" counteracting hop bitterness. I used the term "sugar" as a catchall to include sweet tasting compounds that might not actually be sugars. I'm a bit suspicious that dextrins, while not sweet themselves, still might be able to counteract some hop bitterness, probably not a well as sugars though. Maybe they directly compete for binding sites on the taste buds. If this is the case, then mashing high can reduce bitterness, but not because mashing higher made the beer is sweeter. The mis-assumption is that because the bitterness is less, it must be because mashing high resulted in more sweetness in the final beer.