Stuck Fermentation

Post #1 made 6 years ago
Sorry, I am sure there has been a load of similar stuff already, but nothing totally answers my question.

Been BIABing for about a year, rarely without an issue. A week ago, brewed a porter, and, although I was predicted an OG of 1.059, I hit 1.055. That's fine.

I did mash at a higher temperature than usual, as I wanted something with a bit more body and residual sweetness. I pitched a vial of White Labs English Ale yeast on 2 gallons of wort.

Predictions at 63% attenuation are a FG of 1.020. However, after 5 days I had hit 1.030, and the fermentation looked rather slow (it had looked slow from day one tbh), and today (7 days), I am still at 1.030.

I understand that a higher mash temperature may give a lower apparent attenuation due to unfermentable sugars, but calculating this depression is difficult. Finding this page (http://beertech.blogspot.co.uk/2009/12/ ... final.html) the suggestion was an app. attenuation of 60% (FG=1.024).

Either way, I'm still way out. I have roused the wort and yeast this morning and moved the FV into a warmer sport (although there was no issue during the winter!). But my gut instinct is that I'm stuck at 1.030. I know I could repitch a yeast starter or something (strangely I have done this once before - also on a dark beer - and nothing really happened!!!). However, to be honest, it's still 3.2% ABV and it tastes really good. So I am happy with the product, I am just worried whether barrelling this could lead to all kinds of unmentionable nastiness once it starts to secondary ferment in the barrel!

Would welcome your experiences.

Post #2 made 6 years ago
paulnwright,

Been there, done that! When I have had a stuc(key) like that I have re-pitched and nothing really happened. The beer turned out to be just fine. It seams like you thought it out correctly but it hasn't fermented as you expected? I say just drink it up and not worry about it.

There are lots of reasons for stuck fermentation's. lack of nutrients, lack of oxygen, poor quality yeast, Shocked yeast, pH levels? Every once in a while it just doesn't ferment out right! It sounds like you know your stuff! Relax and have a home brew! Every time I have a beer that I have screwed up or just doesn't seem to go right. It turns out to be a great and (unrepeatable) beer!
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tap 2 Bourbon Barrel Porter
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Post #3 made 6 years ago
Hi Paul

I'd have done the same as you and gave it a rousting. As its on day 7 I'd also be patient and leave it till at least day 10. If there is no more movement I'd barrel, no harm will come to it by barreling with a slightly higher FG than predicted and as the barrel will have a safety valve any excess pressure will vent off.
I used to get stuck fermentations with kits and have barreled them at around 1.025 then left them to condition for 4 weeks. They always turned out good.

One other point is have you calibrated your hydro in plain old water ? worth checking..

Edit...Beaten by Bob :idiot:
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Post #5 made 6 years ago
BobBrews wrote:It sounds like you know your stuff!
:dunno: Never feels that way, Bob!

Thanks, guys......had other advice to give it a few days and re-pitch. Someone also suggested a fast ferment test (http://braukaiser.com/wiki/index.php?ti" onclick="window.open(this.href);return false; ... rment_Test) which looks like an interesting move...would at least tell me not to worry about putting the stuff into a barrel without things going 'Pop' :thumbs:

As I say, it tastes really good at the moment, and fermenting it out some more may dry it out more than I wanted. As long as I can now store it safely, I will take the hit on the ABV and settle back with a brew :drink:
Last edited by paulnwright on 13 Jun 2012, 19:12, edited 3 times in total.

Post #6 made 6 years ago
Well, the Fast Ferment Test sat in the airing cupboard for two and a half days....overpitched with a pack of Munton's bog standard yeast.....just taken a gravity reading...1.030. Looks like I'm good to go and barrel!

Post #7 made 6 years ago
Hi there Paul,

Before your next brew, maybe buy another thermometer if you don't have a few already. A second hydrometer never hurts either.

It is possible, if you are using a digital thermometer, that it has 'broken' and that you might have been actually been mashing at very high temps. 1.030 FG is really high so I think something has gone quite wrong here.

I'm not experienced enough in this area but I think stuck fermentations should be very rare and could only be caused by the most extreme situations such as a sudden decrease in wort temperature during fermentation. If a stuck fermentation occurred for any other reason, eg very bad water chemistry, I can't see how you will ever 'unstick' it no matter what you do.

So, check your existing mashing thermometer by buying a second one of a totally different brand/type and make it preferably non-digital. You certainly don't want to see your next beer finish at 1.030.

I like these accidents though as you'll probably find the beer tastes great or has some characterisitc you would have never otherwise discovered. Please let us know how it tastes at the end of the day so we can all learn a bit.

I bet you it won't taste awful though :peace:,
PP
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Post #8 made 6 years ago
Hi PP!

No, I have a traditional thermometer. My issue is heat control, and I know I got up to 72C at one stage, but no higher. As I say, my aim was to mash higher than the 65C I usually aim for (and I've never had problems hitting OGs or projected FGs). So I can only conclude there are lots of unfermentables, or my OG reading is too high, and my efficiency worse than I thought - I did take an OG whilst the wort was hot, along with a temperature reading, and converted. Strangely when I have had this problem before it has been with darker beers (this has 58% MO, 20% crystal, 9% aromatic, 7% choc malt, 7% roasted barley)

You say I don't want to see a beer finish at 1.030....apart from lack of alcohol (;-]) is there any other reason why this is not desirable.

As I say, I quite like the sweetish end of what I have just barrelled, it works well against the roasted barley, but a bit more alcohol would give it better body.

Cheers

Paul

Post #9 made 6 years ago
paulnwright wrote:You say I don't want to see a beer finish at 1.030....apart from lack of alcohol (;-]) is there any other reason why this is not desirable.
The thing that was worrying me was the numbers pointing to something going very wrong somewhere. You'd expect a 1.030 FG on something like a Russian Imperial Stout! You certainly wouldn't want to be brewing an APA and having a 1.030 finish :P.

Your post above though shows a recipe with quite a massive proportion of 43% specialty grains. A typical porter (in fact, even a Russian Imperial Stout) recipe would usually only have about 15% so I think some, maybe even most of the story lies there.

Specialty grains contribute only a bit lower yield than a base malt however, the yield they contribute attenuates a lot less than that from a base malt.

Maybe on your next porter, look for a recipe that is more like 85-90% base malts. I think that will solve the problem and the final beer will be better balanced.

;)
PP
Last edited by PistolPatch on 17 Jun 2012, 17:45, edited 3 times in total.
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Post #10 made 6 years ago
Thanks PP

Must admit the more I read the more I wondered if the roasted grains were the issue. I knew they gave you lower yields upon mashing, but, as you suggest, I now realise they also attenuate less well. Looks like my software can cope with the former, but not predict the latter (presume it works off the quoted app. Attenuation of the yeast from its database, but cannot work out how fermentable the wort is in the first place!)

Oddly, it doesn't taste too unbalanced...to me, although it is yet to condition

Let's see what comes out the barrel n a fortnight's time. It's all a learning curve.

Post #11 made 6 years ago
The "sugars" in crystal malt do not get broken down further in the mash, as they are "locked into place" during the mashing in the husk that occurs during the production of the crystals. So that could partly explain the high FG.

Post #12 made 6 years ago
Ah....is that why one of my favourite beers 'Sarah Hughes' Ruby Mild' has a real sweetish edge? I know they use quite a lot of crystal....I assume if they do not attenuate so well, that leaves the beer sweeter?

Post #13 made 6 years ago
I get confused on this area i.e. I don't really know what the difference is in taste between a dextrous wort (unfermentable sugars - dextrines) and a sweet wort (maltose and glucose?) though apparently there is one. (Beachbum might be able to help us on this one.)

All I do know is that dextrines add gravity but don't ferment and that specialty malts contribute more dextrines.

Also, your high mash temp will have had the same effect - OG doesn't suffer too much however the final gravity will be much higher. So the combination of these two factors in your brew makes quite a difference.

By the way, have you got a link to the original recipe? I wouldn't mind seeing why the specialty malts percentage is so high. I'm not knowledgeable about recipes but I'm pretty sure I have never seen one as high as this.

:peace:
PP

P.S. I'm 99% sure that there isn't any software that can formulate the change in attenuation caused by specialty malts. I've certainly never seen any sort of formula written to cover this particular area. I suspect that most recipes do not have a high enough proportion of specialty malts for it to make a major difference and most grain spec reports probably don't have the raw information needed either. I don't think colour alone could be used as a basis for such a formula :dunno:.
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Post #14 made 6 years ago
I was at a Weyermann lecture in New Zealand in 2010 where they said that some European breweries use a lot of Cara-products - particularly Carapils - to produce full flavoured but lower alcohol beers. He said you can use up to 35% Carapils in a brew, to make a "mid strength" lager, which raised a lot of eyebrows at the time (not to mention oohs and aahs) - I don't think Dextrins are sweet as such but do add "chewyness" that could maybe be sensed as a sweetness.

Post #15 made 6 years ago
I like these accidents though as you'll probably find the beer tastes great or has some characterisitc you would have never otherwise discovered. Please let us know how it tastes at the end of the day so we can all learn a bit.

I bet you it won't taste awful though
Well, opened a tester bottle saved from going into the barrel. Great mocha-ish nose, and some really nice roasty, chocolate on the palette. The bittering came out just right, nowhere near a stout, although it reminded me a little of Mackesons with that sweetish taste. At 3.3%, more like a nice dark mild.

As I say, it could do with a bit more 'umph' from a higher ABV, for me, but this is the best BIAB I have done - partly, I think because I have now moved on to treating the water I use too (I was always getting a bit of a twang which seems to have gone since I have been doing this).

So, all in all, a mistake, but nowhere close to an undrinkable one! :P
Last edited by paulnwright on 02 Jul 2012, 19:09, edited 3 times in total.

Post #16 made 6 years ago
Good stuff Paul ;) and congrats on getting rid of the twang. What aspect of the water was causing it do you think? How did you fix it?
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Post #17 made 6 years ago
What aspect of the water was causing it do you think? How did you fix it?
Although I use bottled water, because my municipal supply is very hard and definitely has chlorine in, when I looked at the analysis, I still had plenty of bicarbonate, and my mash pH was very high (well over 6). I felt I was losing a bit of life from the taste, and the bitterness was really harsh (not really hoppy, almost metallic). I knew this problem varied, and varied with what kind of beer I brewed (I know now this was due to the different grain bills altering pH). So, I just used either this site or this site to calculate adjustments. I could use carbonate-reducing solution, but its cheaper to boil the water with some gypsum for 30 mins, let it cool, rack off the water from the precipitate, heat, dough in, and then add appropriate amounts of gypsum, epsom salts, and calcium chloride!

Two other things I have noticed since changing, and I do not know if related, my extraction efficiency has increased or is more stable than before, and the amount of gunk and break material I generate has decreased dramatically, giving me nice clear ale.

It would be great to just use my local supply, but the water it is so hard, its analysis is not easy to come by (apparently), and they don't measure Mg, that for my small brews (10l), bottled water is still economical.
Last edited by paulnwright on 04 Jul 2012, 03:00, edited 3 times in total.

Post #18 made 6 years ago
Paul, thanks for your great reply above and apologies for my belated thanks. It's end of financial year here so my mind has been fully pre-occupied with questions like, "Can I claim a tax deduction on my brewstand which I also use in my day to day work?" :lol:

And, it is a great answer. Just goes to show how many individual problems a brewer might face depending on where they live.

Efficiency into kettle can be drastically affected by pH so your observations there are probably not anomalies. If you have done another brew since posting the above I'd be really interested to see if the twang problems have gone for good.

Hope so!
PP
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