2nd BIAB - poor effeciency

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Kudzu

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I cranked out my 2nd BIAB on the weekend and was a bit disapointed with my efficiency.

The first brew one went pretty well, I followed the BIAB tutorial on this site, including the Schwartzbier recipe. Ended up with an OG of 1.050 which was south of the target but according to brewmate was 75%, which I thought was decent enough for a first attempt.

Second brew was a SMaSH with 5Kg of JW Trad Ale and PoR. Target OG for this brew at 75% efficiency was 1.052 according to Brewmate. I ended up with 1.040.

Grain was ground on the same mill with the same gap as brew one.

Differences in mash:

Brew 1:
  • 90 minutes at 66C
  • Grain in at flame on, stirred continuously until mash temp reached - mainly to stop the bag burning on the bottom of the kettle
  • Temp wasn't too stable as pot wasn't insulated, got down to 64 after 40 minutes, I heated back to 66, was down under 64 again by end of mash
  • Regular agitations for first 40 minutes as per schedule in tutorial
  • Grain out at 90 minutes, drained and squeezed bag in bucket and added extra wort back to kettle.

Brew 2:
  • 60 minutes as 66C
  • Didn't get the grain in until water was about 50C, stirred from then until mash temp reached
  • Insulated pot with old sleeping bag, Temp was maybe 65 at end of mash.
  • Only agitated once at 30 minutes as wanted to keep the pot wrapped up.
  • Grain out at 60 minutes, drained, squeezed etc.

So where did I go wrong with brew 2? The main differences I can see are mash length, dough-in temp and amount of agitation. Which is likely to affect the efficiency most? I'll brew again this weekend with the same grain bill and see if I can do better.

Should mention I didn't have enough water for brew 2 and ended up with 19l into the fermentor the 1.040 was after diluting back to 23l. Brew 1 was pretty much spot on.
 

gordo_t

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Howdy,

Are you measureing your pre-boil gravity?

I got caught out originally using Brewmate and trying to match my post-boil (OG) gravity readings to work out efficiency and everything was all over the place, until i was steered right.

I now take a gravity reading preboil and use Brewers Friend online temp adjusted calc to work out the gravity http://www.brewersfriend.com/hydrometer-temp/

And then plug everything into the Brewers Friend efficiency calc http://www.brewersfriend.com/brewhouse-efficiency/ to work out the efficiency.

Everything has been pretty consistent from batch to batch since (few points here and there, but no wide variances)
 

Phoney

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Without knowing your volume of water that you started with it's difficult to say. If you ended up with the right OG at the end of your boil but missing 2 - 3 litres, I would have left it at that.

It's also possible that because you're mashing it at a cold temperature and then ramping up it's doing weird things with your conversion. There's all sorts of enzymes and whatnotz that react differently at different temperatures. Try getting your water up to strike temperature (68 - 71C whatever your brewing software recommends) and then doughing in so that you land at 66C.

Not sure what guide you're reading, but unwrapping the insulation, agitating and heating up is a waste of time. Just wrap it and forget it. It's far more important to mashout. That is at the end of the mash heat up to 77C while constantly agitating, then hoist that bag.
Hope this helps!
 

Crusty

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Kudzu said:
I cranked out my 2nd BIAB on the weekend and was a bit disapointed with my efficiency.

The first brew one went pretty well, I followed the BIAB tutorial on this site, including the Schwartzbier recipe. Ended up with an OG of 1.050 which was south of the target but according to brewmate was 75%, which I thought was decent enough for a first attempt.

Second brew was a SMaSH with 5Kg of JW Trad Ale and PoR. Target OG for this brew at 75% efficiency was 1.052 according to Brewmate. I ended up with 1.040.

Grain was ground on the same mill with the same gap as brew one.

Differences in mash:

Brew 1:
  • 90 minutes at 66C
  • Grain in at flame on, stirred continuously until mash temp reached - mainly to stop the bag burning on the bottom of the kettle
  • Temp wasn't too stable as pot wasn't insulated, got down to 64 after 40 minutes, I heated back to 66, was down under 64 again by end of mash
  • Regular agitations for first 40 minutes as per schedule in tutorial
  • Grain out at 90 minutes, drained and squeezed bag in bucket and added extra wort back to kettle.

Brew 2:
  • 60 minutes as 66C
  • Didn't get the grain in until water was about 50C, stirred from then until mash temp reached
  • Insulated pot with old sleeping bag, Temp was maybe 65 at end of mash.
  • Only agitated once at 30 minutes as wanted to keep the pot wrapped up.
  • Grain out at 60 minutes, drained, squeezed etc.

So where did I go wrong with brew 2? The main differences I can see are mash length, dough-in temp and amount of agitation. Which is likely to affect the efficiency most? I'll brew again this weekend with the same grain bill and see if I can do better.

Should mention I didn't have enough water for brew 2 and ended up with 19l into the fermentor the 1.040 was after diluting back to 23l. Brew 1 was pretty much spot on.
Are you sure you are measuring your efficiency correctly......... :ph34r:

A 90min rest is far better than a 60min rest with full volume. Just heat to strike temp, grain in, cover & leave it be for 90mins. Raise temp to 78deg after the rest for your mash out, continually rousing the mash whilst heating to 78deg. Once you hit 78deg, turn off the heat & lift the bag. If you aren't in the mid 70% range or higher doing this, I'd be double checking your crush.
 

philmud

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The guys at G&G, Geoff who does the BIAB demos included, advocate stirring every so often (I think they said 15 mins). My first BIAB was around 65%, but the second time round I followed this advice & got over 75%. I also raised the temp to mash out. Sure you lose more heat, but you can add some flame & bring it back up if you need to.
 

Phoney

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Fair enough, I used to stir, then I gave up and found no difference in efficiency. Similarly with 60 min mash or 90 min mash.
 

philmud

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I've only got a sample of two BIABs to go off, could also have been a different crush, or any number of variables
 

carpedaym

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Kudzu

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Thanks for the responses.

GTG, no didn't measure pre-boil gravity, will do so next time.

Phoneyhuh, started with 33 litres on the second brew, I was expecting this to be a little low, as 38l was pretty much spot on for a 90 minute boil (second brew was 60 minute boil, did I mention that?) thought it was better to end up a bit low than high as it's easier to add water than take it away.

Crusty, not at all sure I'm measuring my efficiency correctly. I'm just using the efficiency rating on the main screen of brew mate and adjusting until the indicated OG is the same as my post boil gravity. I just know I was 10 points lower on my second attempt when Brewmate was predicting a similar OG. I'll try heating to strike temp, before dough in and do a mash out and see how it goes.

Carpedaym, no water-grain ratio wasn't the same as one was a 90 minute boil and the other 60 minutes.
 

bum

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Water to grain ratio in the mash.
 

GuyQLD

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While higher L:G is known to give better efficiency in a broad sense at the ratios you're talking bout it becomes a minor factor.

In full volume BIAB the three biggest factors that affect efficiency are;
1. Crush
2. 90min mash
3. Mash out

After that PH, L:G and grain bill play roles but probably not worth looking at until you are confident the rest of your process is right.

You should always check your pre boil gravity and volume in my opinion. This tells you how much sugar you extracted. Any other measurements past this point are a measurement of your ability to recover that sugar.
 

wbosher

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I've done a few BIAB brews now mashing for only 60 minutes, sometimes even less if going for a higher temp, with no problem...excluding my last brew which was an abject failure due to poor crush and possible infection. :(

I agree with the points made about stirring, just cover up and leave. If well insulated, you shouldn't loose more that a couple of degrees, if that.

I always mash out, although the benefits of this for BIAB seem to be a bit of a contentious subject, but certainly can't hurt.
 

bum

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I recall a very helpful and knowledgeable user (who may be from before your time) called Thirsty Boy detailing (on many occasions) the many reasons why the opposite of everything you just said is more correct. Have a search if you're at all interested in improving your process. You may not think it is worth the effort, that's fine - close enough often is good enough.
 

wbosher

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I do recall reading a very long post from TB about that which is precisely why I do mash out. I actually even tried to find it to paste a link in my previous post, but work got in the way...thanks boss. ;)

If I recall, the thread I'm thinking about was mainly to do with the mash out rather than the actual mash times, 60 or 90 mins, but there were a lot of differing opinions about it...hence my comment "although the benefits of this for BIAB seem to be a bit of a contentious subject".

Like I said, I always mash out, and IMO it does make a difference, but there are plenty of far more experienced brewers out there that say that it's not required for BIAB. This is not just my opinion, I've read it several times on this very forum.

As for the mash times, that also is quite contentious, also based on what I've read here on this forum from experienced brewers. Once again, NOT just my opinion. What IS my opinion, is that a 60 minute mash seems to provide good results for me. Brewhouse efficiency according to Beersmith is up around the mid 70s, which I'm perfectly happy with. I was getting the same results mashing for 90 minutes, so shortening it doesn't seem to have made any difference.

I'll continue to try and find the thread I mentioned if I get the time, it's a very interesting read.
 

bum

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wbosher said:
I've read it several times on this very forum.
You say that as though it is a recommendation...

You're saying things on this very forum, wbosher. Things you admit you don't really understand and yet someone else will come along later and take is as gospel. Just like you have.

Shorter mash times may be acceptable for lower mash temps rather than higher as you suggest.

Stirring the mash can certainly be beneficial. Particularly for BIAB due to the lack of vorlauf and "proper" sparging, iirc.

Benefits of a mash-out with BIAB are not debatable at all. There's just lazy pricks everywhere who don't give a shit. That's not the same as the effects being debatable. Same goes for pretty much EVERY issue under discussion on this forum.
 

wbosher

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You say that as though it is a recommendation...

You're saying things on this very forum, wbosher. Things you admit you don't really understand and yet someone else will come along later and take is as gospel. Just like you have.
I'm talking about posts from experienced brewers, like yourself, manticle, TB, and the like. Not saying that these actual people were involved in the discussions I'm talking about, just that sort of experience based on what I've read here...if that makes sense.

Shorter mash times may be acceptable for lower mash temps rather than higher as you suggest.
This is the complete opposite of advice I've been given by manticle (who I do regard as an experience brewer, and who's opinions I value), I asked about making a low alc beer, he suggested that a 70ish degree mash for 30 minutes will do the trick (among other things like yeast etc...)

Stirring the mash can certainly be beneficial.
Agreed, but not essential. This is based on both my own limited experience, and that of said "experienced brewers".

Benefits of a mash-out with BIAB are not debatable at all. There's just lazy pricks everywhere who don't give a shit. That's not the same as the effects being debatable. Same goes for pretty much EVERY issue under discussion on this forum.
I tend to agree with this one to a point, with the exception of the (once again) said "experience brewers".
 

bum

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wbosher said:
I'm talking about posts from experienced brewers, like yourself, manticle, TB, and the like. Not saying that these actual people were involved in the discussions I'm talking about, just that sort of experience based on what I've read here...if that makes sense.
It makes perfect sense and is reasonable. Forms the basis of my point, actually.

Note the strikethrough. How is a new brewer to tell the difference between the advice of brewers like TB and Manticle and the advice of brewers like you and me?

They can't. We need to consider if we know the things we say to be true or not. "Someone else said it" isn't much of a defence - although is a reasonable caveat to make. Such understandings should certainly be shared but we need to make a qualification that they may not always be true.

wbosher said:
This is the complete opposite of advice I've been given by manticle (who I do regard as an experience brewer, and who's opinions I value), I asked about making a low alc beer, he suggested that a 70ish degree mash for 30 minutes will do the trick (among other things like yeast etc...)
That is a very specific "trick" though and I'm not sure he'd say the same is a good idea in the general case. You can't do that if you were brewing an IIPA, for example. Well, you could but it'd probably be crap.
 

Kudzu

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I've got a shit tone of this grain. Think I'll keep doing SMaSHes with same amount of grain for a while, changing one thing at a time and seeing what makes the biggest difference.
 

wbosher

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bum said:
It makes perfect sense and is reasonable. Forms the basis of my point, actually.

Note the strikethrough. How is a new brewer to tell the difference between the advice of brewers like TB and Manticle and the advice of brewers like you and me?

They can't. We need to consider if we know the things we say to be true or not. "Someone else said it" isn't much of a defence - although is a reasonable caveat to make. Such understandings should certainly be shared but we need to make a qualification that they may not always be true.
Fair call. That's why when I'm regurgitating someone elses advice, I'll often put something like "I read somewhere that...", looking back I didn't do that here.

In regards to knowing who's experienced and who is not, that is just based on old threads that I've read. Probably not the best way to judge who the good brewers are out there, but you can get a feel by what others say about other people...although it's no guarantee.

You make a valid point about noobs taking advice from other noobs like myself, and blindly trusting in what we say. A lot of my opinions are based on what I've either experienced myself, or what I read here, so if the noob were to do a search, he'd probably read the same stuff that I'm saying anyway, and possibly believe that...I'm just providing a shortcut to that information. :lol: But seriously, I take your point and do agree with it.


bum said:
That is a very specific "trick" though and I'm not sure he'd say the same is a good idea in the general case. You can't do that if you were brewing an IIPA, for example. Well, you could but it'd probably be crap.
Agreed, we were talking about milds from memory, or at least a way to take a moderate strength pale ale and turning it into a low alc pale ale with plenty of body and flavor, something I still haven't quite got but getting closer.

What were we arguing about?

EDIT: Kudzu - sorry for hijacking your thread...as you were.
 

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