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04/16/07 10:22 AM  
Lambic questions
I'm trying to figure out some stuff for an upcoming lambic brew. Anyone have any thoughts on the following questions?

1. Is there really starch in lambic wort? I know Sparrow says there is, but I'm not 100% convinced. Looking at the turbid mash schedule it seems possible that even the turbid runnings get converted (by alpha only, and to quite unfermentable wort) when they get added back to the mash. Unless some crazy person has performed an iodine test at Cantillon open brew day or something, I'm not sure how to answer this.

2. Why would I want starch anyway? I don't think brett can actually eat it, but I'm not positive.

3. Has anyone used the Wyeast pediococcus to make a nice sour beer without big diacetyl problems?


Al B
04/17/07 08:14 AM  
Re: Lambic questions

<<Why would I want starch anyway?>>

Homebrewers may not really need starch, since Homebrewers usually (I say usually) inoculate with only a few bugs, where true lambic has all kinds of critters. In that case, starch is beneficial for the long run. I would tend to think.

You probably know this more than I, but I think stach is made up of a ton of saccharides. So over the course of months, not days, perhaps Bretts will widdle this complex molecule down slowly - since they have the means to do this on dextrins (much smaller in comparison) and trisaccharides.

04/17/07 11:19 AM  
Re: Lambic questions
Yeah, that's a good point about other bugs maybe using the starch.

And for the brett... there's definitely a mystery there. My guess is that it's not a mystery to someone, though. Those lambic papers from Leuven would probably be really interesting if they could be found somewhere.

Darel Matthews
04/17/07 09:04 PM  
Re: Lambic questions
If you follow a true turbid mash schedule, you pull off a small portion of your mash liquor right after dough in and immediately heat it to 190, and keep it there for the remainder of the mash. This would effectively denature any enzymes that might convert the starches, which if you're using raw wheat haven't been modified by malting.

Sparrow, p.144 states it's the lactic-acid producing bacteria that require the starches, so I suppose in case of a lambic that's Pedio. Unfortunately he doesn't get into any more specifics in the bug-specific sections.


04/18/07 10:41 AM  
Re: Lambic questions
Thanks Darel. I would agree, if that initial fraction was run right into the boil kettle. What makes me question the story is that instead, those brewers added an extra step by eventually putting that starchy fraction BACK into the mash for a 20 minute rest at 172F.

I think all the beta amylase would be gone at that point (after the 45 minute rest at 149F, and 20 minutes at 162F), but I am much less sure about the alpha amylase. (That's probably something that can be looked up though.) Also I wonder why the old brewers decided this extra step was worth their time. It's possible (but I have no idea if it's true) that the real point is not to put starch in the beer, but to reserve some starch so that it is degraded by alpha amylase only.

I wish Sparrow had given a little more justification for some of the statements about starches, what can eat them, pedio, etc. It's hard for me to just take them at face value.

04/18/07 11:25 AM  
Re: Lambic questions
I respect a man who doesn't read and believe just because! Context is so very important to understanding.
04/18/07 01:59 PM  
Re: Lambic questions
The more I read the less I believe! Or at least, the more "primary sources" I get a chance to look at (papers, theses, etc) the more I realize how much is unknown.

Darel Matthews
04/18/07 04:10 PM  
Re: Lambic questions
When you return that particular infusion to the mash, you should be sitting at 172, which is technically higher than mash-out. AFAIK alpha is denatured at 168, and while I'm positive this is not a 100% complete reaction and some will remain, I doubt it'd be enough to convert much of anything, plus it may be "distracted" by the other sugars in the mash already.

I completely see what you're saying though and I too would have loved a little more in-depth discussion in Sparrow. Anyone know of any pro-brewing texts that discuss this? Probably not.


04/18/07 05:44 PM  
Re: Lambic questions
As I'm sure you know, alpha denatures at different rates at different temps, so we really have to say things like "the half life of alpha at 150F is X, and at 170F is Y."

Numbers I've seen say most of the beta, and about half the alpha, is gone after the 45 minutes at 149. Also apparently an experiment showed that a pound of base malt had enough AA to convert 88 pounds of starch in 1 hr at 149F!

04/18/07 06:00 PM  
Re: Lambic questions
Oops. Accidentally hit "submit." Anyway, there's tons of AA to start. The Cantillon schedule posted by Mike Sharp on the old lambic digest has 45' at 149F and 30' at 172F, before the turbid runnings are added back. So about half the AA would be gone after the 45' 149F rest. And then if you take the crappy rule of thumb that things happen twice as fast at 10C hotter, the AA would again be halved after the 172F rest. 25% left, maybe? With lots of uncertainty?

So... it still seems like a pretty open question.

(Most numbers I gave are from a paper quoted in HBD posts by Steve Alexander, as JIB v97, pp85, by the way.)

Darel Matthews
04/18/07 08:24 PM  
Re: Lambic questions
Perhaps I'll be adding that mash addition to my boil and doing another infusion for MO.
04/19/07 09:30 AM  
Re: Lambic questions
Yeah, if you do want starch, it seems like there's no reason to put the turbid running back in the mash.
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