Problem Solving: Terrible Efficiency

[Spiesy]

Hey everyone,

Had a really weird brew today...

Black IPA - 20l batch, BIAB
5.1kg Trad Ale
2.3kg Munich II
1kg Australian Dark Crystal
250g Australian Chocolate
150g Australian Black Wheat

Strike temp of 71. Dumped in the 8.8kgs of grain into 28.5l of water.
Upon doughing in, I thought to myself - that's a shitload of grain in my 70l pot, I hope there's enough water to get its swerve on, and I hope it hasn't robbed too much temperature.

Anyway, give her a big stir - break up any dough balls, lid on, woolen blankets over. Start the mash.

20mins in, open her up to give her a stir, and take a temp measurement - down to 62. I think to myself, I'll combat this amount of grain and lack of temp in one fell swoop, so add 3.5l of water at 70-degrees.

Mash for one hour, with additional stirring 40mins in (temp of 64 degrees).

48% efficiency... damn. I usually get around 68%. This is one expensive Black APA!

Any thoughts? Mash temp, water/grain ratio - all of the above?

PS: last time I brewed this, it was a double batch, and despite an accidental higher strike temp (by accident, one of my first beers) - it turned out to be an awesome beer.

 

[Spiesy]

My guess is, as already suggested... whilst I'm usually fine mashing in 5.5-6kg of grain in that amount of water at 70-71 degrees, when it's 8.8kg - the grain has absorbed too much heat, making my mash temp lower. And whilst the water/grain ratio isn't bad, if the grain hasn't got enough water to properly steep in, it may not convert as well...

 

[nala]

First question:
Why don't you use some free software like Brewmate to do some calculations for you.
Second question:
If you intend to BIAB, the. water to grain ratio shoud be at least 6-1. Why so little strike water.

You should be using 42.5 litres of water at strike temp of 72o C.

To acieve 20 litres into fermenter your pre-boil volume should be 29 litres.

You should not be surprised at your numbers, particularly if you are guessing at everything.

 

[bum]

My guess is, as already suggested... whilst I'm usually fine mashing in 5.5-6kg of grain in that amount of water at 70-71 degrees, when it's 8.8kg - the grain has absorbed too much heat, making my mash temp lower. And whilst the water/grain ratio isn't bad, if the grain hasn't got enough water to properly steep in, it may not convert as well...

I'm not sure the temp difference would effect efficiency significantly, certainly not to the extent you're observing. I think at those temps it'll have more effect on wort fermentability.

The issue you're having is more likely caused by the second issue you mention here, water/grain ratio. Big grain bills simply get worse efficiency. My usual ~75% drops to low 60% for a big grainbill so your drop is not a tonne more extreme than that. Any chance the crush might have been different here too?

 

[Spiesy]

First question:
Why don't you use some free software like Brewmate to do some calculations for you.
Second question:
If you intend to BIAB, the. water to grain ratio shoud be at least 6-1. Why so little strike water.

You should be using 42.5 litres of water at strike temp of 72o C.

To acieve 20 litres into fermenter your pre-boil volume should be 29 litres.

You should not be surprised at your numbers, particularly if you are guessing at everything.

I do use software. I use BeerAlchemy. I'm not "guessing" anything - it's my 29th brew, and none of the others have resulted in such a low efficiency, hence my post. Mind you, it's only my second single batch IPA.

Your numbers don't make up, mate... how do you start with 42.5l of strike water and end up with 29l pre-boil?

Where did the other 13.5l go? Only 8.8l would have gone with the grain - which leaves 4.7l missing. Or am I missing something?

To answer your second question, though - I normally save the amount of water than the grain robs (normally 1l/kg) and rinse the grain with it, at degrees, once my bag is draining... That's why I started with 28.5l of water.

 

[Spiesy]

I'm not sure the temp difference would effect efficiency significantly, certainly not to the extent you're observing. I think at those temps it'll have more effect on wort fermentability.

The issue you're having is more likely caused by the second issue you mention here, water/grain ratio. Big grain bills simply get worse efficiency. My usual ~75% drops to low 60% for a big grainbill so your drop is not a tonne more extreme than that. Any chance the crush might have been different here too?

Yeah, okay, thanks bum. I'm still getting grain from a store, so I can only guess it was milled correctly.

It was sitting in a cupboard after milling for 2-weeks also.

Perhaps all these factors have combined to give me one, low efficiency...

 

[warra48]

Large grain bill with a relatively low temperature equals:

1. At least 1 to 1.5 litres of water retained in the grains. This is also of quite a high gravity, compared to lower gravity brews.
2. Poor extraction of the available sugars because of relatively low viscocity of the wort

You have 8.8 kg of grains, and only 28 litres of water. That's about the ratio I use, and I use a 3V system and batch sparge with a mashout.
I'm not surprised you achieved the result you did.

One other thing I often read is that large grain bills give lower efficiency. That's probably the end result, but I believe not technically correct. What really happens is that you only extract the higher gravity early runnings. If you were to run of an amount in proportion to your grain bill, compared to other brews, your efficiency would not be much different. Really, you are doing a party gyle type brew without the second lower gravity brew. Happy to be proved wrong.

 

[seamad]

Water volume (strike) out by a fair bit. Grain absorption will give you your batch size before any boil losses trub etc, plus efficiency drops in the high concentrate of the mash, I'd be starting with minimum 36l plus wind your eff down 10 %.

 

[Crusty]

Hey everyone,

Had a really weird brew today...

Black IPA - 20l batch, BIAB
5.1kg Trad Ale
2.3kg Munich II
1kg Australian Dark Crystal
250g Australian Chocolate
150g Australian Black Wheat

Strike temp of 71. Dumped in the 8.8kgs of grain into 28.5l of water.
Upon doughing in, I thought to myself - that's a shitload of grain in my 70l pot, I hope there's enough water to get its swerve on, and I hope it hasn't robbed too much temperature.

Anyway, give her a big stir - break up any dough balls, lid on, woolen blankets over. Start the mash.

20mins in, open her up to give her a stir, and take a temp measurement - down to 62. I think to myself, I'll combat this amount of grain and lack of temp in one fell swoop, so add 3.5l of water at 70-degrees.

Mash for one hour, with additional stirring 40mins in (temp of 64 degrees).

48% efficiency... damn. I usually get around 68%. This is one expensive Black APA!

Any thoughts? Mash temp, water/grain ratio - all of the above?

PS: last time I brewed this, it was a double batch, and despite an accidental higher strike temp (by accident, one of my first beers) - it turned out to be an awesome beer.

I just punched that recipe into BrewMate & it's all over the place.
20lt batch @68% efficiency tells me to strike in with 32.21lt water @71.2deg.
OG - 1.092
FG - 1.023
9.04%
It's more like a DIPA & is not within the guidelines for an IPA, 1.056 - 1.075.
Not saying that it's not a good beer, I haven't made it but that grain bills too big for that batch size IMO.

 

[labels]

I get 10Kg grain into a 50L pot so I don't think it's grain/water ratio that's your problem. It's just that you can't get away with it in a BIAB system. In a 3V brewery, I batch sparge up to three times which leaves no sugar behind. Efficiency between 75 -80%, occasionaly higher. However, I am doing 50L batch so I can afford to flush a lot more water through the grain where you can not do that. Check the crush as well - most common cause of low efficiency.

-=Steve=-

 

[GuyQLD]

I Where did the other 13.5l go? Only 8.8l would have gone with the grain - which leaves 4.7l missing. Or am I missing something?

To answer your second question, though - I normally save the amount of water than the grain robs (normally 1l/kg) and rinse the grain with it, at degrees, once my bag is draining... That's why I started with 28.5l of water.

You're using 1L per kilo for loss to absorption. Not everyone uses this - your numbers look normal though for 20L if that's your absorption (taking into account your sparging process).

Your last comment scares me somewhat. Two really important steps in the conversion process were interrupted by your process. Firstly - Temperature is too low and you don't leave it long enough to recover. Your early temp was too low; you recognised this and attempted to correct it. But you needed to go higher - 66-67 at least in order to activate enough alpha amylase to get enough conversion.

You also remove the bag and then rinse it - No mention of what temperature water you use. Don't bother. Just mash with more water and do a proper BIAB style mash out i.e. 1 Degree per minute or so from 65-78 degrees. This gives the remaining alpha amylase a bit of a kick before denaturing them giving you a few more points eff.

You could have probably saved this batch by raising to 67 degrees and letting the mash continue for a total of 90 minutes, then doing a mash out. You would still expect a drop in efficiency from the larger grain bill but somewhere in the 60's as opposed to 48%.

 

[labels]

<snip>
Your last comment scares me somewhat. Two really important steps in the conversion process were interrupted by your process. Firstly - Temperature is too low and you don't leave it long enough to recover. Your early temp was too low; you recognised this and attempted to correct it. But you needed to go higher - 66-67 at least in order to activate enough alpha amylase to get enough conversion.
<snip>

Hate to cut in but I can't say that I agree with your conclusion. Yes, the temp was too low to start with but so what, step mashes are like that anyway. And, it was still in beta range. Secondly, he didn't have to go to 66-67 alpha to achieve conversion, lower temps usually achieve higher conversion than high temps anyway (not going into details) and time wasn't really an issue either - most conversion is over in the first 20 minutes.
It is much more likely that either (1) he overloaded the BIAB system he has or (2) The crush was too course - or both. I'm betting on an overloaded system which made any form of sparging near impossible because the pot was too full for the boil and a pile of sugar got tossed out with spent grain.

-=Steve=-

 

[felten]

You have a massive pot for a single batch, no issues overflowing the pot. Tipping water into the grain bag isn't really the best way to sparge, you would be better served just mashing in with the full volume IMO.

There are a few programs/spreadsheets that are optimised for BIAB/full volume brewing and can help calculate your initial strike volume.

Beersmith 2 is one, Brewmate I think is another though I've not used it, there is also the "official" calculator on the BIABrewer.info forum, and this old school version here (which is what I use every brew day).

Also you don't say if you're doing a mash out or not, adding a ramp to mash out while constantly stirring the mash will increase efficiency.

 

[Spiesy]

Thanks to everyone for their feedback. It's interesting how there lots of differing opinions... no wonder a newer brewer can get confused!

Correction: when I said 20l batch, that was incorrect. I end up with 20l in my keg, but it's actually 25.5l batch.
4l gets thrown out as trub, and I lose around 1l in the fermenter to sediment/trub/etc. I have another 0.5l into the "loss" equation just because... if I end up with 20.5l, I'll bottle the extra. Sorry for the confusion.

VOLUME
My volumes are correct. I know this because I started off with the volume I wanted and ended up with the volume I wanted. So I don't think the volumes are an issue... the only issue in regards to volume would be when the volume is added. I.e. with a grain bill such as this, perhaps I would have been better off starting with all the water in the pot, rather than rinsing the grain later on. Sounds like this is the case.

I find it odd that some members are recommending I raise the temp of the mash, with using BIAB... unless I have some sort of protection in my pot (which I don't), I'll run the risk of melting my bag - wouldn't I?
The only other option would be to raise the temp via infusion, which means I wouldn't be mashing with the full volume required for such a big grain bill.

Do a lot of BIAB's add heat to the pot when they have their bag in there?

 

[Spiesy]

It is much more likely that either (1) he overloaded the BIAB system he has or (2) The crush was too course - or both. I'm betting on an overloaded system which made any form of sparging near impossible because the pot was too full for the boil and a pile of sugar got tossed out with spent grain.

-=Steve=-

My pot isn't anywhere near being overloaded - as mentioned in the OP, I've done this brew as a double batch before without issue. It's a 70l Craft Brewer pot. No dramas there.

 

[GuyQLD]

I BIAB with a pot and a 3ring gas burner and apply direct heat without issue. Some use cake racks to lift the bag from the floor - I don't bother and just ramp up a bit slower.

I use a full volume method, with a liquor to grain ratio of about 7:1. Your ratio for this grain bill was about 3.5:1 which is getting into the realms of traditional ratios in a 3V system. Only you're not using a traditional sparge and bigger bills are notorious for lower efficiency (and while you pour water over the top - you don't have a proper grain bed - I'll wager you're getting massive channelling and really not getting anything out of it). A dunk sparge might work - but I've tried half a dozen variants to BIAB (dunk sparge, infusion mash out, what you do with lifting the bag and pouring water through it) and I get far more consistent results with full volume, proper temperature and a mash out.

I think Labels was right about one thing, your LHBS is doing your crush so it's something that may be affecting and outside of your control.

Funnily enough this thread has been going the same time as the mash schedule thread in which Bum posted this link;

http://aussiehomebrewer.com/topic/54273-rack-for-biab-any-ideas/page-2#entry897732

Which is a pretty straight forward assessment by TB. If you want to understand more though I find braukaiser a great reference - It has a good balance between science and writing it in a way poor old me can understand. In particular the section on Ezymes and Starch conversion.

 

[Spiesy]

cheers, Guy

 

[bum]

VOLUME
My volumes are correct. I know this because I started off with the volume I wanted and ended up with the volume I wanted.

It is worth noting the difference between hitting your volume targets and having ideal targets in the first place (it is also worth noting that you missed a fairly important target and hitting this volume target is basically what caused that). Greatly changing grain/water ratios changes efficiency which changes possible/likely maximum potential for a given system (even though some seem to want to give lunatic advice that suggest otherwise). It looks to me like you're using numbers that work for a smaller beer and expecting them to work for a bigger one. That's not really how it works. You often need to change process when you do different things - there's no one-size fits all in this game (hence the confusing advice you note above).

 

[Online Brewing Supplies]

Big beers = less efficiency
I drop it by 6% but thats my system yours will be different.
Nev

 

[Spiesy]

Got it. Thanks lads - it's good to be learning.