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"Stuck" Fermentation hell? No. Just mash temps

Post #1 made 8 years ago
by Inconceivable
Hi all

I thought I'd share my story of mashing fails that I thought for a month or more was actually stuck ferments. It wasn't, I've learned a valuable lesson, and I'd like to share it.

Long story short; by not correctly controlling my mash temp I was leaving too many unfermentable sugars it would seem.

I'm a new brewer starting in August '15 and here's what I encountered recently:

Batch #009 - German Pils (Brewing Classic Styles): my OG 1044, target FG: 1009, my FG: 1019
Batch #010 - Sierra Nevada Pale Ale clone ('Nierra Sevada' from HBT forum): my OG 1040, target FG: 1012, my FG: 1018
Batch #011 - Brewdog 5am Saint clone (Brewtoad Recipe database): OG 1044, target FG: 1012, my FG: 1020
Batch #012 - Janets Brown Ale (Brewing Classic Styles): OG 1064, target FG: 1017, my FG: 1026

In each of the above cases I couldn't get the FG to move short of extreme measures; I roused & warmed, pitched more yeast via starter, I tried some brewers yeast from a local craft brewer, I even tried Champagne yeast vs Janets Brown but none of these methods would shift my FGs across these batches.

I despaired and despaired and each hydrometer reading on 'stuck' batches was like a kick in the guts.
For batch 10/11 I eventually blitzed the bastards with Low carb sachet (dextrose glucoamylase enzyme) and smashed their FG down to 1008 for #10 and 1003 for #11 but to the real detriment of each beer.

Eventually I was speaking to my LHBS and the guy immediately said "Oh you Biab, well that'll be your problem."
Me: "....."
<thinking to myself double facepalm this guy is an idiot>

Eventually I steeled myself to pursue this line of conversation and he explained that people with stove/ gas fired BiaB in his experience tend to have fluctuating mash temps and he bet I was mashing too high, denaturing my Beta Enzymes and thus leaving too many unfermentable sugars; thus my beers weren't actually stuck, they were just finished fermenting the sugars my mash had produced. He suggested mashing in an Esky will give greater temp control (3V) or if I wanted to stick with Biab I could try to mash a couple of degrees lower to give myself some buffer and avoid going too high.

Now my commitment to Biab is 100% and I've no intention of going to 3V/ HERMS/ RIMS/ etc so naturally I looked to the Biabbrewer.info community for answers
Simple practises like always stirring vigoursly up/down when firing the kettle and waiting to check your temp wasn't drifting up before dough-in came to light. I didn't have to just drop a few degrees to be safe I still should be able to mash at the right temp but now I had better procedures to ensure my entire body of water was the right temp before dough-in.

So that's what I did for batch #14 another crack at the SNPA clone and batch #15 a rebrew of the NRB all Amarillo Biabrewer.info recipe that I've tweaked a lot, and I'm pleased to report that for at least #14 so far no sign of a high FG. I am bloody sure I didn't go over 69c in either batch and am therefore hopeful I didn't hurt my Betas too much and thus my wort will be more what the recipe calls for.

I hope this story can provide a chuckle for anyone who's mashed too hot and a lesson for anyone who hasn't cottoned onto the importance of mash temp or is facing "stuck fermentation issues"

Lastly on a side note I was inspired by a Brulosophy article (link below) that led me to think the taste difference for a much higher FG may not be death for a beer, so for Batch #12 I just bottled J'anet Browns' with the crappy ADF% and see how it goes. I opened the first tonight and it was delicious!
http://brulosophy.com/2015/10/12/the-ma ... t-results/

cheers
Nick
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Post #2 made 8 years ago
by PistolPatch
Nice post Nick :peace:,

I think your brew shop guy had sort of the right idea but not quite. Firstly, BIAB gives you excellent mash temp control (you actually can't control it in an esky except by adding hot or cold water which defeats the purpose of full-volume brewing). In BIAB, you can apply heat at any time whilst agitating the mash.

There are two issues to focus on:

1. Make sure your strike temperature is correct or a bit low.

I'm not sure if you tried the BIABacus to work out your strike temperature however, the default is for a low strike temperature. It's also the only 'program' that allows you to adjust your strike temperature (see section X to adjust). The reason for this adjustment relates to the second issue...

2. Heavy equipment will actually continue to heat your mash even after you turn the flame off. A kettle with a heavy base, sitting on a heavy stand, radiates heat far more than an electric urn say. If your equipment is 'heavy,' this phenomenon can definitely weird you out - why is the temp still going up even though I turned the flame off two minutes ago :argh:.

Download the first BIABacus file in this thread. Look at the second line of Section E. You'll see it says to strike at 66.7 C to get a mash temp of 66 C. Now go to Section X and type '5' into the third line. You'll now see that the strike temp jumps to 69.6 C.

So, don't over-ride the default until you get a feel for your equipment. Always agitate before taking temp checks and, if you have heavy equipment, learn how long it takes after you turn the heat off for the temp to stop climbing.

And even before all the above, make sure yu never trust a single thermometer. Many thermometers are either inaccurate to some degree to begin with or can become so over time.

:peace:
PP
Last edited by PistolPatch on 10 Apr 2016, 21:16, edited 1 time in total.
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Post #3 made 8 years ago
by joshua
PP, your 2nd point is right.

When you use a 1600F flame to heat a low Convection metal, the bottom of the Metal is 1600F,
and the Top of the Metal is 159F.

The Metal will take time to Equalize, to 74F in the Bottom(Room Temperature), and 160F on the Top, when the heat is removed.

Use Aluminum!!!
Honest Officer, I swear to Drunk, I am Not God.
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Post #4 made 8 years ago
by Lumpy5oh
I think a pot fashioned out of tin foil would be best!
Some people are like slinkies. Not good for much, but bring a smile to your face when pushed down the stairs.

Weehoosebrewing.ga
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Post #5 made 8 years ago
by joshua
Lumpy5oh, tin has a low melting point, so, you would need a Wood Fired heat source.

Be a True European and Brew in "no-Lead" Brass!
Image
Last edited by joshua on 11 Apr 2016, 04:26, edited 1 time in total.
Honest Officer, I swear to Drunk, I am Not God.
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Post #6 made 8 years ago
by Inconceivable
Thanks to all

@PP I do use Biabacus as my primary brewing tool and I have found the suggested strike temp is obviously not working on my aluminium kettles (24L and 50L) as I always cool past the desired mash temp then invariably need to flame on to slowly bring it back. Once I have a little more data I'll have a crack at overriding section E defaults as I dial-in my equipment.
I've been relying on my Thermapen only but I'll make a point to crosscheck it every now and then with my cheaper dial thermometers too

I have found that my aluminium doesn't allow the heat to creep up too much more once I flame out, but I stir and circulate the sweet liquor to be totally sure that what the Thermapen reads is in fact a consistent temp

I guess the real thing that struck me about this situation, as a beginner, is no matter how much I'd read it just never 'clicked' to me that mash temps could so significantly leave so much unfermentable sugarand leave the FG so high and erm... not dry.
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Post #7 made 8 years ago
by Mad_Scientist
Thank you for your post. I enjoyed reading your provided link over the weekend, that seemed like a nice side-by-side Ex-beer*iment on mash temperatures.

In an older system / setup of mine, when I was BIAB'ing in my keggle heating with propane, I had a dial thermometer mounted low on the wall. By gently heating, I would see the dial thermometer rise and that gave me a good indication of what was to come. I would stop heating at or a degree or two above my mash temp and after stirring, the mash would eventually catch up after 5 or 10 minutes.
Batch #011 - Brewdog 5am Saint clone (Brewtoad Recipe database): OG 1044, target FG: 1012, my FG: 1020
I have been looking at the Brewdog pdf and see that this recipe calls for a 1.050 OG and a 144° F mash temp. Did you follow that recipe or something some guy posted on Brewtoad?

I myself have been struggling to hit a particular FG on a clone recipe. The brewmaster says to mash at 152° F, but I find that's just not the case, as last time I brewed it, I mashed at 151° F using a recirculation electric PID controller and only hit a 73.5% AA while am supposed to get a 77% AA. Next time I brew this clone I will try something like mashing at 145° F.
Last edited by Mad_Scientist on 12 Apr 2016, 02:08, edited 1 time in total.
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Post #8 made 8 years ago
by joshua
M_S, there is a slight problem with Mashing at less than 147/64C.

Tha Alpha Enzymes work on Single Glucose separation, so a High Graivity(>1.040) take longer than 90 minute to mash.

So, if you can Keep The Gravity recorded, and see when the gravity curve flatens, you can get the Best AA possible.

BTDT, YMMV
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Post #9 made 8 years ago
by Inconceivable
Mad_Scientist wrote: I have been looking at the Brewdog pdf and see that this recipe calls for a 1.050 OG and a 144° F mash temp. Did you follow that recipe or something some guy posted on Brewtoad?
.
I'm afraid to confess it was some guys recipe on Brewtoad here https://www.brewtoad.com/recipes/beatified-dawn" onclick="window.open(this.href);return false; and is hardly high integrity.

I only just got the news Brewdog had released all their recipes to the Homebrewing community (here: https://www.brewdog.com/diydog" onclick="window.open(this.href);return false; ) and wish I'd had their actual recipe to try instead.

So afraid I'm no help on the low mash temp question except to say that another clone I'll be launching soon is Matt Bryndilsons Firestone Walker Union Jack and that recipe calls for 60 mins at 145f (62.8c) then 10 mins at 155f (68.4c) so if mashing quite low is good enough for him.....

cheers
Last edited by Inconceivable on 12 Apr 2016, 18:49, edited 1 time in total.
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Post #10 made 8 years ago
by Mad_Scientist
I'm saying that no one is wrong here. I follow a high integrity recipe and can't hit a number (AA%) that a brewmaster gives during an interview.

I believe hitting an AA % per a specific grain bill is the last frontier.

We brew on and do the best we can.

Has anybody hit all the numbers on Brewdog's recipes? :dunno:

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Post #11 made 8 years ago
by PistolPatch
Mad_Scientist wrote:I myself have been struggling to hit a particular FG on a clone recipe. The brewmaster says to mash at 152° F, but I find that's just not the case, as last time I brewed it, I mashed at 151° F using a recirculation electric PID controller and only hit a 73.5% AA while am supposed to get a 77% AA.
I wouldn't be worried about the 3.5% difference mate. There's a few reasons.

For example, your pitching rate and yeast health might be different. Your water won't be the same either. More importantly though...

Such a difference is very hard to measure. Even if your OG was 1.060, the difference between 73.5 and 77% apparent attenuation is only two points (1.015/9versus 1.013/8) which is very hard to measure with any great degree of accuracy.

This brings us to the real point I think. What does the beer taste like? In my opinion, I doubt you would be able to taste the difference between the two scenarios above. So, is the beer tasting great or not? If yes, then keep brewing. If not, then what don't you like about it?

In other words, chasing the taste is much more important that chasing someone else's numbers.

Hope that makes sense/helps :scratch:,
PP
Last edited by PistolPatch on 12 Apr 2016, 22:42, edited 1 time in total.
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Post #12 made 8 years ago
by Mad_Scientist
Thank you PP for your personal response. Like the OP, this beer mentioned above always tastes good.

I guess more tweaking and drinking is in my future :)



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