3 Questions: attenuation, patent malt, diastatic specialty malts

[stronk]

Firstly, is it possible to influence the attentuation of a yeast by the temperature it ferments at (or any other way than pitching a different yeast)? I want to make a sweet stout, but I only have quite high-attenuation yeasts, which I suppose will make it dry. I don't like the taste of lactose or artificial sweeteners, so I'm a bit stuck.

Secondly, I have been formulating a recipe and read on a couple of sites that black malt does not contribute at all to the flavour of a beer, but only to the colour. Is this true? And just what is the difference between patent malt and black malt (I suspect there is none)?

Lastly, I'm out of reliably diastatic grains (I'm trying to use up my remaining ingredients before I leave my improvised brewery for 6 months on a gap year trip). Is carapils at all diastatic? I have read that it is not, but not from a particularly trustworthy source. If it helps at all, I used vienna malt in my last brew to convert some rolled oats and it worked surprisingly well.

Thanks for the help (pre-emptively).

[ray m]

Well, I guess I'll try to take a stab at this for ya, Stronk...

Q1: I don't think that temperature directly affects the degree of attenuation, but it does affect how quickly it will fully attenuate (i.e., beers will fully attenuate more quickly the warmer the ferment temp.). As you pro'ly already know, higher temps also give way to more esters and other possibly unwanted stuff. However, if you suddenly crash the temperature to stop yeast activity, I guess it could arguably be controlled, but then you'd have a problem when it comes to bottling time, since the yeast need warmer temps to carbonate/condition the beer. You'd end up with bottle bombs, I think. I have personally had really good results with White Labs English Ale yeast (WLP002) when I wanted a nice malty character to my brew. Edinburgh Ale works ok too, but I like the English yeast better.

Q2: Black malt & (black) patent malt are the same thing. I think the difference you're thinking of is black malt vs. roasted barley. Both of these grains will most definitely add flavor character, depending on how much you use. If you use @ 2 to 3 oz. of either one, it will affect color, but flavor contributions will be somewhat slight. Using anything over 1/4 lb. will start to affect the flavor. I think black malt is the more harsher tasting, contributing a more acrid, burnt toast character/flavor. Roasted barley is a little milder. If you don't want a particularly harsh, burnt-ish character to your brew, use chocolate malt, but that may skew your brew out of style if you're concerned about adhering to stout style guidelines.

Q3: I would not at all depend on carapils as a base grain, if this is what you're getting at. Vienna has been known to actually be a good base malt. Carapils is not intended to be a base malt, so I would chuck this idea.

Hope my insight helps...most importantly, I hope its correct (I know Brewmonkey & Stodbrew, as well as others, will correct me if I'm wrong about roasted grain thing).

:)

[stronk]

Thanks for the reply.

I brewed this today and here are what I felt were answers to some of the questions I had:

The torrefied wheat and carapils converted nicely within an hour. Which grain this was due to I couldn't tell (though it's definitely one of the two, as there was nothing else in the water except some gypsum).

Black malt did have a milder flavour than roasted barley, which contributed to my suspicions that it's mostly used for colouring. Roasted barley tastes strongly of burnt toast, black malt tastes mildly of charcoal.

About the yeast questions I have no idea.

[danno]

stronk, as far as I know, the only way you can really use temps to control attenuation is to crash cool and stop yeast activity. problem with that, if you want to naturally carbonate it, yeast activity will pick right up where it left off when you bottle...

and it's probably a little late now, but a warmer and thicker mash would result in the sugars being less fermentable, giving a sweeter, maltier beer... (cite (http://www.howtobrew.com/section3/chapter14-6.html))

[stronk]

That'll help in the future. As for crashing, I need this to sit for 6 months before I drink it, so it wouldn't work. One surefire way to stop fermentation (this is used to make sweet wines) is to use sodium metabisulphite to kill all the yeast before bottling/kegging. The trouble with this is the lack of natural carbonation (and I need to bottle, not keg).