First BIAB, low OG, Why?

[MCW]

So did my first BIAB on the weekend using a crown urn.

The recipe called for:

2.7kg pale (I added 3kg)
1kg wheat
500g Vienna
200g caramalt

Got water to 70 and pitched grain to find it dipped to only 68 which was higher than expected (will tweak for next time). I then let it mash for 60mins. After that I took another reading and my temp had dropped to 66.8, again more than expected considering it was insulated, wrapped in a sleeping bag and the day was 32 degrees. So I then hu g the bag over a bucket while the wort got up to boil and then squeezed as much out as I could. Boil went fine, losses a by more than expected but within limits. Anyway afterwards I cubed and then chilled before pitching then following day.

Well the concern is the planned OG was 1.057 and the actual was 1.040. That's a bloody long way off and I was hoping ppl might be able to provide any info as to why I missed the mark by so far?

 

[gap]

How much water did you use in the mash?
Did you take a preboil gravity reading? This quickly shows whether you are on track.
What was the preboil wort volume?
Do you use brewing software, this will also help you keep track of what is happening during the brew.

 

[earle]

What batch size were you aiming for? For a 23L batch size (fermenter) in a crown urn with an efficiency of 75-80% I don't think you're that far off the mark. Problem could be more with your calcs which gave you that expected OG, than with your brewing process.

 

[MCW]

Gents

Calcs were taken off Beersmith 2. I used 31 L for the mash, forget the pre boil volume but the post was 21L (planned 23L) for a 19 L batch. Obviously these are things I'll try get more accurate next time.

The biggest problem I find with Beersmith is finding a BIAB profile that accurately represents my mash technique/brewing process. Would A 90min mash yield more sugars?

 

[xenon2000]

Do you own a refractometer? If not , it's almost an essential for AG brewing I have found. You could then take a quick reading at the end of mash to see if your numbers are indicating wether you have got a good extraction rate at that stage. If not , give it a good stir , a quick heat up perhaps and give it another 30 minutes. Takes a lot of the guesswork out of brewing ,that's for sure.

 

[Bribie G]

If I were doing that brew on my system, BIAB in urn, I'd also be looking for mid - 1050s and would generally get it. I'd definitely get a refractometer if I were you, mine is just about welded to my left paw whenever I brew.

BIAB gives similar efficiencies and gravities to 3 vessel systems, Braumeister etc (at a systems wars brew day a few years ago in Brisbane the efficiencies were independently checked by umpires on the day and all came out around 76).

However if you want software that has a BIAB option I'd recommend BrewMate, while it's still available.

 

[paulyman]

Did you stir the mash and check for dough balls? Some brews I get none and others it takes a few minutes of careful stirring and pressing the dough balls against the side of the pot to get rid of them.

 

[Droopy Brew]

. Would A 90min mash yield more sugars?

At a mash temp of 68C you are at saccharification temps so it is likely you have yeilded all available sugars in the first 30-40 minutes.

 

[Rocker1986]

I do 90 minute mashes and stir it every 20-25 minutes then a number of times while ramping up to mashout, and after mashout as well. I have only started doing this regularly on the last 2 or 3 batches but have found it has increased my efficiency. I also use the let bag drain into a bucket then squeeze it and tip this excess back in later, although I wait until about 25 mins left in the boil to do this.

Beersmith I have found great even for BIAB in an urn or whatever. You can create an equipment profile or edit an existing one to better fit your system if need be. I use the 40L Urn BIAB profile and have simply edited it to suit my process. Works well and I generally hit the numbers I'm after.

I'm not sure how much effect the grain crush itself has on BIAB brewing but I have read that it can affect the efficiency as well so maybe something to look at too.

 

[dannymars]

My first BIAB was super low, mainly due to crappy crush by store....

 

[Diesel80]

The biggest factors to me achieving greater control of O/G and F/G are as follows (I was once all over the shop as well):
1) Boil off rate analysis. Which involved accurate measurement of starting volume and final volume. Now have a trusty ruler and spreadsheet and get within a bees **** each batch. I adjust flame during boil to achieve desired post boil volume.
2) Up-scaling to a double batch size, this assisted in nailing down #1 as I have a large pot - due to large losses on smaller batches.
3) Paint masher at dough-in to make sure no lumps. 5 mins pumping the mash. Then 5 mins doing the same @ 60 mins before raising the bag. I found stirring during the mash did nothing if it was done at the start and then the end. There was no diff in the trials I did. So I skip the mid mash stir.
4) Squeeze bag till near dry whilst boil ramps up. I sit it on a rack over the kettle and press it down with the paint masher. Spend about 5-10 mins doing it after lighting the kettle.

3 and 4 made the most difference.

Efficiency went from 65-70% to 81%, now I squeeze a little less and settle on 75%. Furthest out I have been for O/G has be 2 points (on a 1.055 target) since starting this regime with est efficiency at 75% in software.

This is for 54L post boil, with 6L trub, and allowing for cooling at 4% or whatever to get my final volume of around 2x Cubes 43-46L depending on cube spec.

Grain crush since day 1 was set at a Credit Card thickness and not been change in 3+ years since I got my mill.

Hope that helps you out. Much more satisfying achieving what you plan than getting mystery beer!

Cheers,
D80

 

[indica86]

I'd expect 1048 from that in my crown urn. If I set BS2 to 85% total efficiency then I can get 1055.
Over confident for your first brew perhaps?

 

[louistoo]

Yep I use 5kg or 5.1kg to yield 1.050 in my biab no sparge system. Dunno how you expect mid .050's from 4.7kg in OP's grain bill there Bribie G. you must be doing better than me haha

 

[Spiesy]

As Diesel80 mentioned, crush of the grain is also important. Other things that could factor: is your thermometer accurate? Are your gravity reading accurate, and adjusted for temperature - where needed (most hydros are calibrated to 20-degrees).

End of the day, I would recommend focussing more on consistency rather than high efficiency, as long as your efficiency is reasonable (70% and above). The difference between 70-80% efficiency is really only a couple of dollars, and really high efficiencies can be detrimental to the finished beer.

 

[motman]

I thought it is often recommended to have a longer mash for biab, as u need to make up for the sparge period in 3v systems, which biab misses out on. I generally go 70 mins, ramp up to mash out and leave at mash out temp for ten. Gives about 95mins.

Having said that, my efficiencies are not that great, about 70 at 1.056. However, if you adjust beer smith so you know what you are going to get, then the cost difference is minimal, as is the stress!

 

[contrarian]

I use the BIABacus for all my calculations and find it a very handy tool with good estimates of how much grain you need to hit targets.

I would also suggest focussing more on the process than the numbers for the first few brews. Measure gravities, volume and temperatures along the way and keep good records as this will help you learn your system.

A 90 minute mash does make a difference as does a mash out and they are the simplest place to start.

Don't worry too much about it. The first few brews are a steep learning curve but at the end of the day you're still making beer!

 

[MCW]

Thanks so much for all your responses. I've tweaked my BS2 profile to more accurately represent my process from what I learnt on the day and now I'm only a few points off with a 70% efficiency.

Certainly looks like I have a Sh!t tonne to learn and just when I was getting comfortable with extract. I'll take on board all you tips and hopefully have a more accurate brew day next time. Thanks again all.

 

[wynnum1]

If you are doing in crown urn starting out at a lower temperature and heating up may be easier . also how did you measure temperature depending how thick mash is temperature can vary depending where you measure needs a good stir..

 

[ianh]

Another factor is volume of water and how did you measure it. I found the best way is using a steel rule to measure the depth of water. I use a Crown urn and the calcs are in the spreadsheet pinned to the forum.

I would suggest using a 70% efficiency till you get more brews under your belt.

 

[Westo]

1 - 2 deg C loss over 1hr mash is normal,,for the crown urns, try lowering your mash temp next time if you want a higher starting OG as 4.7kg grain with a 68c mash will yield a lower OG. maybe go 65-66c next time