What factors influence sweetness?
 

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?

Mash temperatures. Mash thickness. Easiest is mash temps. For a very sweet malty beer mash at 154 or higher. Dryer beers mash sub 150. Experiment with your favorite yeast and recipes to find the right balance. Mash thickness has some effect too but I dont recall exactly what it is.

I enjoy a sweeter beer and plan on mashing my Rogue Dead Guy clone at 152 to 154 to bring out a maltier character.

I think you are trying to talk about MASH temperature, not fermentation temp. You are right, higher mash temperatures create more unfermentable sugars in general. However, you are confusing unfermentable sugar with dextrins (which are more like starch than sugar). They are NOT the same. Dextrins have no taste in general, but the sugars are still sweet, although nothing like table sugar (eat some lactose and you'll know what I mean).

These are a few of the sugars and sugar-like carbohydrates that may or may not be fermentable depending on the strain of yeast under anaerobic respiration:
Cellobiose
D-Galactose
D-Glucitol
Glycerol
Inulin
DL-Lactate
Lactose
Maltose
D-Mannitol
Melezitose
Melebiose
Methly-alpha-D-glucopyranoside
Raffinose
L-Sorbose
Succinic Acid
Sucrose
Trehalose
D-Xylose
Xylitol

Even maltotriose is only very slightly sweet, and that is fermentable. Lactose of course is readily fermentable, just not to brewers' yeast.

That high mash temperatures create sweet beer is a homebrewer's myth that doesn't stand up to the slightest scrutiny.

Charlie Bamforth was on a Brewing Network show a while ago and recommended mashing in the 160s to make a low alcohol beer. Someone in the chat asked "won't that make the beer sweet?" and his reaction was basically "why the hell would you think that?"

Didn't Bamforth also say that he doesn't believe dextrins are responsible for mouthfeel? Or maybe it was 'wholly responsible' or something.

I have recently found that lower attenuating/higher floccing yeast that yields higher FG doesn't necessarily translate to increased mouthfeel. WY1968/WLP002 English Ale yeast doesn't leave a particularly full mouthfeel but is a very high floccer. While not a very scientific/controlled experiment, a guy in a small homebrew club split a 10 gal batch into 2 carboys and used Wy1968 in one and Wy1007 (German ale) yeast in the other. The German ale yeast batch had a noticably fuller mouthfeel but lower FG.

Yeah he said "we don't know what affects mouthfeel but we know it isn't dextrins" or something very close to that. It's amazing the stuff he'll say like everybody and their mother knows it that contradicts what every homebrewer "knows". The last time he was on he said that malt has enzymes that inhibit proteolysis such that you can't get much proteolysis in the mash (the inhibiting enzymes are not active at malting temperatures).

Meaning that protein rests are BS?

I thought he said it was because they were denatured during kilning but could be confusing this with something else.

Isn't a lower FG going to mean more alcohol? Alcohol is thinner than water, hence the term 'apparent attenuation' so if removing more solids (fermentable sugar vs dextrins) and replacing it with alcohol doesn't affect mouth feel/body then I'm confused on what "mouth feel" means I guess.