All Grain - Calculating unfermentable sugars?

[robertvrabel]

How does one calculate the amount of unfermentable sugars when mashing at a certain temperature?

I just made my first AG (oatmeal stout), but I mashed higher than I think I should have. I did it at about 160 for 1 hour. It was higher than I wanted to, but I freaked out and decided to close the cooler and let it go, figured It would be better than messing with it trying to lower it.

Now after doing more research, i understand the higher mash temp will create more unfermentable sugars. Just how much though? My pre-boil OG was 1.049 with 71.2% efficiency. OG was 1.063. Just curious how sweet this stout is going to turn out... its been 48 hours since I pitched, and from looking into the carboy krausen hasn't even started :x seems to be fermenting very slowly.

EDIT:
I used Wyeast 1084 - Irish Ale, did my first starter of 800ml 2 days earlier as well.

 

[Grizzlybrew]

I may be wrong, but I don't think there's a clear-cut formula for figuring this out. I'm actually listening to the Brew Strong Attenuation podcast as I drive around today at work. There's a multitude of factors that go into attenuation - Grain Bill (grain types), Composition of extract (if you're using), mash temp, etc.

As with most things, keeping careful records (especially when repeating the same beer) will give you the best idea of how your set up works.

I would say the good news is that you pitched an ample amount of yeast, but the new BYO/Basic Brewing article claims pitching rates may not affect attenuation. ester production, etc. as much as we once thought...

 

[robertvrabel]

Thanks for the response. I figured there wasn't a clear cut way to figure this out... but was just wondering if there was something you could go off of. I'm just curious how much each degree effects the amount of unfermentable sugars. I learned my lesson from now on for how hot my mash water needs to be to bring it to the right temp. I over estimated and it was to hot... I should ahve just threw some ice in to cool it down, but under pressure I just decided to wrap it up and try to maintain it rather than messing with it.

Just hoping this thing takes off soon... its been 48 hours, with a starter, and there isn't any signs of krausen yet. Worried that there isn't a lot of fermentable sugars... or I screwed my starter up.

 

[PT Ray]

You'd think someone somewhere has made identical batches using different mash temps for some usable data. I've heard all the talk like everyone else about mash temps but can't say I've ever read someone putting it to the test.

Wouldn't surprise me if this turns out to be another case of "as much as we once thought".

 

[GilaMinumBeer]

I think Kaiser does this but, not by calculation.

IIRC, he actually pulls a sample fo the wort and side ferments it hot to really drive the yeast through it. Fast ferment test or something like that.

The point is to quickly determine the limits of fermentability of each batch to guage the actual batches attentuation.

 

[Grizzlybrew]

I should ahve just threw some ice in to cool it down, but under pressure I just decided to wrap it up and try to maintain it rather than messing with it.

My personal experience tells me that it's much harder to bring the mash temp up than it is to chill it down. Especially if you are already at full mash volume capacity. I've found myself on more than one occasion running off wort, doing pseudo-decoctions mid-mash... not pretty.

 

[smmcdermott]

I do not do AG, yet....I have been researching, b/c i plan to switch this year. I have heard, read, watched, etc. and think that i remember the lower the temp and longer time (to a certain degree) the better the efficiency. I would imagine this would lower the amount of unfermentables, but not sure there is a way to calculate that exactly.

Again, don't really know, just throwing some info out there, shoot me down if I am wrong please.

 

[Grizzlybrew]

I do not do AG, yet....I have been researching, b/c i plan to switch this year. I have heard, read, watched, etc. and think that i remember the lower the temp and longer time (to a certain degree) the better the efficiency. I would imagine this would lower the amount of unfermentables, but not sure there is a way to calculate that exactly.

Again, don't really know, just throwing some info out there, shoot me down if I am wrong please.

You're kind of correct. I think your terms are just throwing you off. Lower temps and a longer mash would result in a more fermentable wort and greater attenuation (or efficiency of attenuation if you want to think of it that way). Typically though, brewers refer to (mash) efficiency as the percentage of available sugars in the grain that you are able to extract to your wort, regardless of their fermentability.

 

[smmcdermott]

close enough....haha, thanks.

 

[david_42]

There isn't an formula for calculating unfermentables, just empirical observations. Although we talk about high mash temperature creating more unfermentables, even that is backwards. Everything starts out unfermentable, high mash temperature means less conversion to fermentable sugars.

 

[GilaMinumBeer]

There isn't an formula for calculating unfermentables, just empirical observations. Although we talk about high mash temperature creating more unfermentables, even that is backwards. Everything starts out unfermentable, high mash temperature means less conversion to fermentable sugars.

Ayup. It is backwards. I always just looked at it like this, Higher temps equal denatured enzymes. Denatured enzymes = lower conversion of starches.

 

[robertvrabel]

So is it possible to create a batch that is like 60+% unfermentable sugars? I pitched 72 hours ago with a starter (first one), and I haven't even see any karusen appear it. I'm worred that either I don't have a lot of fermentable sugars, or my yeast was bad and I need to repitch. For all my previous extract with steeped grains, I've seen krausen appear after atleast 2 days.

Doesn't seem like this one wants to take off. Thoughts on this?

 

[jwwdvm]

I have no personal experience, but I like Gila's idea; try Googling forced fermentation.

 

[GilaMinumBeer]

It's possible. But doubtful if you are using extract. Most extract is produced under controlled conditions.

Again, you could test your wort by doing a forced fermentation to determine the levels of unfermentables. Otherwise, suspect the yeast or the temperature conditions of the wort.

 

[robertvrabel]

Yeah that does sound like a good idea. I plan to take a reading tonight to see where its at and I'll just throw some of the wort in my flask, add the Nottingham Ale Yeast (since its only $1.59) and see where it ends up. If that ferments, then i'll just repitch the same wyeast.

 

[robertvrabel]

It's possible. But doubtful if you are using extract. Most extract is produced under controlled conditions.

Again, you could test your wort by doing a forced fermentation to determine the levels of unfermentables. Otherwise, suspect the yeast or the temperature conditions of the wort.

It was not extract... this was actually my first all grain. Temp is around 67-69F right now. I do like the idea of forced fermentation, I will give that a ago.

Guess it'll be a learning experience!

 

[GilaMinumBeer]

To have a wrot that is 60+% unfermentable means you pretty much cooked your mash and had little conversion. An Iodine test will provide some indication that mass amounts of starches are present.

I'd be more suspicious of the yeast.

However, if you could provide some more specific info on your grist and yeast we may be able to further help you.

 

[robertvrabel]

Here is all the details on my recipe and procedure.

Oatmeal Stout

Marris Otter 8lb 0oz
US Flaked Oats 2 lb 0oz
US Roasted Barley 1lb 0oz
US Chocolate Malt 1lb 0oz
UK Dark Crystal 1lb 0oz

Yeast
Wyeast 1084-Irish Ale

Steps:
Used 1.7 gallons of ~190F water to pre-heat the cooler (about 15mins)
Added 3 more gallons of 175F water.
I mashed around 160 (maybe just a little higher). I know this was a mistake on my part, my strike temperature calculation was wrong since it was my first time, but I decided to close it up and just go with it.. not knowing it would create less fermentables.
Sparged with 3.8g 185F water.
Ended up with 6.5g pre-boil OG of 1.049 (71.2% effeiency according to BeerAlchemy)
Boil boil after that for 60mins.
Dumped the whole starter into the carboy
Left it at 67-69F

Starter:
Smacked the pack 12 hours before pitching it into the starter. The starter was 900ml of DME wort... and I did it 2 days earlier than brew day.

 

[GilaMinumBeer]

Okay. There is part of it. 30% of your grist (minus the oats) is comprised of unfermentables plus the high mash temp. while I would not blame the mash temp alone ( I have mashed as high as 158*F and had complete conversion).

 

[robertvrabel]

I see now... I guess I will have to adjust my recipe now knowing this. I didn't know that a majority of it is unfermentable. When adding it to BeerAlchemy I didn't even realize that.

I might have to dump this batch then, as its probably going to turn out super sweet since the FG is going to be way high.

What would you recommend? Just let it go for a week and see what the FG turns out to be?

 

[GilaMinumBeer]

I see now... I guess I will have to adjust my recipe now knowing this.

I might have to dump this batch then, as its probably going to turn out super sweet since the FG is going to be way high.

What would you recommend? Just let it go for a week and see what the FG turns out to be?

I recommend a Forced ferment test and more yeast. You wanted a Stout, maybe this will be like a RIS. Taste the wort and see what the specialty sweetness/acridity is like.

I am never one to advocate dumping a batch until all is lost. You've gotten this far, see it through and drink your mistakes to learn from them.

Beside, while I'd not go that high with crystal/specialty. I could be wrong about the ratio be off balance against you. I wouldn;t say the majority is unfermentable based on specialty just the higher end of the ratio. 30% is, in my mind, pretty high but that also depends if you got any fermentable conversion from the oats.

Either way, I say you should follow through with it. Maybe try another yeast. What else have you got to lose?

 

[robertvrabel]

Thanks for your help. I agree I'd rather not dump this batch... I will try everything I can before doing so. I'll just plan to add another smackpack (ofcourse first checking the SG). If the FG is way high after 2 weeks after doing that, and it just tastes god awful...then I probably will have no choice but to dump it =/ . But maybe the sweetness won't be so bad.

I'll plan to just make another batch, adjusting the recipe, mashing at around 154, and seeing how that turns out. It will be nice to compare the taste between them.

This will be one hell of a learning experience... but I guess you gotta start somewhere

 

[GilaMinumBeer]

Thanks for your help. I agree I'd rather not dump this batch... I will try everything I can before doing so. I'll just plan to add another smackpack (ofcourse first checking the SG). If the FG is way high after 2 weeks after doing that, and it just tastes god awful...then I probably will have no choice but to dump it =/ . But maybe the sweetness won't be so bad.

I'll plan to just make another batch, adjusting the recipe, mashing at around 154, and seeing how that turns out. It will be nice to compare the taste between them.

This will be one hell of a learning experience... but I guess you gotta start somewhere

Was this a recipe from a known brewer?

Or a first try at putting it toghether?

I am all for going out on your own to understand griost ratios. In fact, in 3 years I have never brewed someone elses recipe and have only done a few kits BUT,

I arm myself with every home brewing text available. The best for recipe developement without actually giving recipes is "Designing Great Beers". Heady but indespensible.

 

[david_42]

Buy some alpha amylase and add it. It's cheap and although it works more slowly at fermentation temperatures, it does work. Certainly better than tossing the batch.

 

[robertvrabel]

Was this a recipe from a known brewer?

Or a first try at putting it toghether?

I am all for going out on your own to understand griost ratios. In fact, in 3 years I have never brewed someone elses recipe and have only done a few kits BUT,

I arm myself with every home brewing text available. The best for recipe developement without actually giving recipes is "Designing Great Beers". Heady but indespensible.

Nope... I put it together myself. I researched some oatmeal stouts just to understand recipes a little bit. Then I threw this together, went out and bought all the stuff and just tried it out.

 

[robertvrabel]

Buy some alpha amylase and add it. It's cheap and although it works more slowly at fermentation temperatures, it does work. Certainly better than tossing the batch.

What exactly will alpha amylase do? And how do you use it?

 

[GilaMinumBeer]

What exactly will alpha amylase do? And how do you use it?

Alpha Amylase is a liquid extract of the enzymes that would have been present in the mash. They are active bewtween 155*F and 167*F (although thier ranges drift a bit over and under) and act by cleaving short chain bonds into sugars from long chains of starches.

Please read this to get a more descript understanding of enzymes and their roles in a mash.

 

[robertvrabel]

Thank you all, this was VERY helpful. I've learned a lot, and will adjust my recipe and technique to create an awesome oatmeal stout the next time I brew

 

[NYCHomebrewer]

I think there is a distinction that has not yet been made between unfermentable "sugars" and sweetness. The longer chain sugars that you obtain in a mash at temperatures higher than 158 or so do not necessarily taste sweet on the tongue. They do contribute to the body of the beer and can contribute a more malty flavor but they do not end up tasting like sugar water.

A beer with these long chain dextrins is not going to taste dry like a beer in which almost all the sugars were fermentable but its not going to taste sweet like a beer with a ton of fermentables where your yeast stall out before completion. Both beers might end up with exactly the same final gravity, but they are going to taste very very different.

You were apparently trying for a dry oatmeal stout. I think you may find the final product to be extremely drinkable if not the session beer you were aiming for, and I'm willing to bet that it doesn't end up tasting sweet either.

 

[robertvrabel]

I just took a SG and its at 1.038 (OG of 1.063). I tasted it, and you are correct... it doesn't taste bad at all! Its actually pretty good... I'm going to do the force fermentation thing to see if it'll get any lower, otherwise I'm not going to worry about it. I can drink it as is, and learn from this to mash better

 

[Grizzlybrew]

Higher temps equal denatured enzymes. Denatured enzymes = lower conversion of starches.

Is it denatured enzymes or is it a different enzyme together? Higher temps mean it's a suitable environment for alpha amalyse, which still convert starches, but they produce not only maltose, but other sugars as well (including some complex unfermentable sugars.)

I pitched 72 hours ago with a starter (first one), and I haven't even see any karusen appear it. Doesn't seem like this one wants to take off. Thoughts on this?

A krausen is not a given with starters, depending on your method. You're probably good at 72 hours and, really, possibly past the prime/peak.

I think there is a distinction that has not yet been made between unfermentable "sugars" and sweetness. The longer chain sugars that you obtain in a mash at temperatures higher than 158 or so do not necessarily taste sweet on the tongue.

I think these two things are so closely related, that it is hard to distinguish for the average brewer and you might even argue that it's a matter of semantics. Higher mash temps produce more dextrins, which could be perceived as body, sweetness or a combination. It is most likely the complex sugars (alpha amalyse produces) that remain after the yeast has done it's work that give "Sweetness"

 

[GilaMinumBeer]

Is it denatured enzymes or is it a different enzyme together? Higher temps mean it's a suitable environment for alpha amalyse, which still convert starches, but they produce not only maltose, but other sugars as well (including some complex unfermentable sugars.)

170*F+ denautures all the enzymes in grain. Question is, how quickly or what percentage of Enzymes are denatured with strikes in this temp range. Obviously not enough to effect the mash signifigantly but, when you approach boiling to achieve your target strike that may be more signifigant.

 

[Grizzlybrew]

170*F+ denautures all the enzymes in grain. Question is, how quickly or what percentage of Enzymes are denatured with strikes in this temp range. Obviously not enough to effect the mash signifigantly but, when you approach boiling to achieve your target strike that may be more signifigant.

I didn't realize you were talking that high. I might have missed something in an earlier post. I agree with the above. I was thinking high-160-165.

And... once again I think I just missed your point. Now, I see you are talking about the strike water, not mash temp. Although I think this is probably similar to the concern, "will near-boiling temp priming solution kill the yeast if I dump it into my beer too early?" Of course, the answer is: yes. some, but not enough to worry about, your beer will still carbonate. I think the same thing is true in strike water, the temp of the water is going to drop so quickly that such a small portion of enzymes should be affected and your mash should still convert...

...I think.

 

[GilaMinumBeer]

I didn't realize you were talking that high. I might have missed something in an earlier post. I agree with the above. I was thinking high-160-165.

And... once again I think I just missed your point. Now, I see you are talking about the strike water, not mash temp. Although I think this is probably similar to the concern, "will near-boiling temp priming solution kill the yeast if I dump it into my beer too early?" Of course, the answer is: yes. some, but not enough to worry about, your beer will still carbonate. I think the same thing is true in strike water, the temp of the water is going to drop so quickly that such a small portion of enzymes should be affected and your mash should still convert...

...I think.

Actually, I think I am blending subjects here. In this case, the higher temp mash would denature Beta Amylase enzymes. BA is responsible for breaking long chain starches into the short chain starches and sugars that AA can further reduce into simpler, more fermentable, sugars.

At lower mash temparatures, even above the BA range there will still be some BA activity although limited. At 160*F denaturization of Amylases is approaching and little BA activity will be present.

So, it's both. At 160 the beta amylases would denature and the AA would be working as hard as they can in a sweat shop.

 

[rgonzale]

Hey I'm pretty new to this but was asking myself (actually Google) the same question and found this page, which suggests that a 10 degree F increase in mash temperature will lower attenuation (and fermentable sugars) from -- for example -- 75% to 65%.

Attenuation - BrewWiki

In your case (which I know is a while ago!), you can rest easy that there should be plenty of fermentable sugars after mashing in spite of the higher temp.

Anyway I'd love to know how it came out? I'm a fan of oatmeal stouts and may try to make one as my next (3rd) effort).