Low Efficiency - Biab :(

[killspice]

Well, I just finished my mash for the Bullshead Kolsch, my first AG in over 2 years, and ended up with about 54% efficiency into the boil. This gave me an OG of 1.043 pre-boil (adjusted for temp) rather than the estimated 1.067 in beersmith.

I am not too concerned as the plan was to do a concentrated boil (~15L) and top up to 19L, but instead I'll just top up get the desired OG, which will be about 14L I guess.

I am not too sure what the issue was, as I hit my temps almost perfectly - 65.3 at start of mash (supposed to be 65.7), with a 1 degree loss over the hour, and then hit just over 70 for the Mash out (supposed to be 71). I drained and squeezed the bag over a collander and added that too.

The only thing I can really think of is the grains weren't consistently milled enough, a significant number of the grains were smashed in my ice-crushing blender, but i think I rushed some of the milling batches so they may not have all been milled. I'll make sure next time this is done properly and see if that resolves the problem.

Mmmm Beer.

 

[manticle]

How was a kolsch meant to give you 1067 preboil?

Tony's recipe from start to finish or some kind of UBER-kolsch?

 

[killspice]

It was scaled to a ~4kg grain bill and targeting a 15L boil + top-up - 10L Mash-In, 6L Mash-out, 4L Sparge (which I skipped and did the bag squeeze instead)


BeerSmith Recipe Printout - http://www.beersmith.com
Recipe: BullsHead Kolsch

Recipe: BullsHead Kolsch

Recipe Specifications
--------------------------
Batch Size: 19.00 L
Boil Size: 15.51 L
Estimated OG: 1.049 SG
Estimated Color: 3.5 SRM
Estimated IBU: 18.7 IBU
Brewhouse Efficiency: 75.00 %
Boil Time: 60 Minutes

Ingredients:
------------
Amount Item Type % or IBU
3.75 kg Pale Malt (Barrett Burston) (2.0 SRM) Grain 94.94 %
0.20 kg Wheat Malt (Barrett Burston) (1.5 SRM) Grain 5.06 %
10.00 gm Saaz [7.50 %] (60 min) Hops 8.1 IBU
15.00 gm Saaz [7.50 %] (40 min) Hops 10.7 IBU
1 Pkgs Kolsch Yeast (Wyeast Labs #2565) Yeast-Ale


Mash Schedule: Single Infusion, Light Body
Total Grain Weight: 3.95 kg
----------------------------
Single Infusion, Light Body
Step Time Name Description Step Temp
60 min Mash In Add 10.31 L of water at 71.9 C 65.6 C
15 min Mash Out Add 6.60 L of water at 80.7 C 71.0 C

 

[MHB]

You really shouldnt have skipped the sparge!
Im not a fan of concentrated mashing, unless you really are trying to up the dextrins in the finished beer, but be that as it may, what moves extract out of the chunks of grain and into solution is the difference in concentration between what is in solution and what is in the chunks.
The lower the water (liquor) to grist ratio (L:G) the more extract is left in the grist, by sparging you lower the amount of extract, which makes the extract in the grist come out into solution.
72oC isnt really a mashout; its about the peak for Alpha Amylase the idea of a mashout is the stop enzyme activity and to increase the fluidity of the liquor, 78-80oC is a better mashout temperature; again in concentrated mashing it can be a bit of a problem getting enough even boiling water into the pot to raise the temperature.
I really think its easier to make better beer in a pot 1.5-2 times the batch size, bigger pot or smaller batch, do the sparge or have a lot higher L:G should see you getting closer to expected yield.
Mark

 

[killspice]

Thanks for the tips Mark -

The Beersmith single infusion profile had the Mash Out temp at 71, but you are right, it would be difficult to get enough water into my pot to raise it to the 80 mark (I had enough trouble getting it above 70). I think in future I would skip the mashout and go directly for a sparge instead, which would give me the room to do a proper sparge. I could also do a higher L:G ratio too, closer to 3.6 than the 2.6 defaulted in beersmith.

Looks like I might be repitching the same recipe directly on the yeast cake when this is ready just to try out your points.

 

[glenwal]

High gravity BIAB needs a sparge. But don't just stop at what you can fit in pre-boil. Keep topping up your pot during the boil with sparge water until about 10mins from the end of the boil. You're going to be topping up at some stage anyway, so might as well do it with suggery goodness.


Also make sure you pot is full to the brim for the mash.

 

[manticle]

It was scaled to a ~4kg grain bill and targeting a 15L boil + top-up - 10L Mash-In, 6L Mash-out, 4L Sparge (which I skipped and did the bag squeeze instead)

Ah OK. Missed the bit about topping up. I shouldn't post late at night after a few pints.

I can't really advise on BIAB concentrated mashes and boils except to suggest that extract efficiency can often drop with larger grain bills which is essentially what you have got in this situation.

There are people who do it successfully so maybe have a look at how they do it, follow that process and see how you go. RDeJvun (can never get the spelling right) and Nick JD stovetop boils - there are threads around somewhere.

72 to me is glycoprotein rest/high end alpha-amylase rest. I aim for 77-78 for mashout.

 

[RdeVjun]

High gravity BIAB needs a sparge. But don't just stop at what you can fit in pre-boil. Keep topping up your pot during the boil with sparge water until about 10mins from the end of the boil. You're going to be topping up at some stage anyway, so might as well do it with suggery goodness.

Also make sure you pot is full to the brim for the mash.

+1 on both counts, those tips will help to get the MaxiBIAB technique to perform in 70-80% range regularly- use water additions (to the boil) to do something constructive.
OP- I'd also mill the grain more consistently, get your supplier to do it perhaps and a finer crush is quite OK for BIAB.
I'd agree with your rationale too regarding mashout/ sparge- make it a combined step is my advice and do it separately in a bucket. So, lift the bag from the kettle, no need to drain it excessively, drop it into a bucket which has 5-6L near- boiling water in it, stir well and drain after 10 minutes, add the liquor to the kettle. You can repeat if necessary (it helps to measure the sparge liquor SG), but remember you don't want an enormous volume of low- gravity sparge liquor, plus it all has to fit in the kettle 10 minutes before the boil end. Another tip is to pre- heat drained sparge liquor in the microwave or another pot before adding it to the kettle, that way the boil is not interrupted when you add it.

 

[Nick JD]

My L:G ratios are very similar to 3V brewers' ratios.

 

[RdeVjun]

Indeedy! :icon_cheers:

 

[Nick JD]

If you're using a blender to crush your grains you should be experiencing really high effiency and hardly need to sparge. When mashing with what is essentially flour, it's like mashing with rice ... the mash converts really, really quickly and your left with a little bag of husks with is pretty easy to squeeze.

What I do is blend with the lid off, and when the 350g batch it's almost blended, flick the grains that don't want to go to the middle in. This ensures all of them are minced good an proppa.

 

[killspice]

As I became more familiar with the grinding I learned that having the blender sideways a bit helped circulate the grains, but at the start I think I left too much untouched. That, the low L:G and not sparging seem to be the key issues here.
I'm getting a second big w 20l pot to sparge in before my next brew, and will look to get better efficiency. In general I am happy with the easy things went if these are my only main problems.

Great feedback guys.

 

[killspice]

(it helps to measure the sparge liquor SG), but remember you don't want an enormous volume of low- gravity sparge liquor, plus it all has to fit in the kettle

I assume you should be looking at a sparge gravity near your estimated pre boil gravity here, otherwise you would just be diluting your wort even more, although if you are way off for volume a little dilution is better than just water.

I want to get back into it straight away now, I like having problems to did

 

[killspice]

I am re-reading the main BIAB thread now after looking for some L:G ratio info and I noticed that agitation during the mash is considered important. Is this still relevant, as this would also be a step I missed this time around.

 

[Crusty]

I am re-reading the main BIAB thread now after looking for some L:G ratio info and I noticed that agitation during the mash is considered important. Is this still relevant, as this would also be a step I missed this time around.

I don't agitate during the mash at all & I get 85% efficiency into the fermenter consistently.
I set the gap on my mill about the thickness of a credit card. I do a single infusion for 90mins & a mash out at 78deg.
My liquor to grain ration for my last APA (23lt batch) was 7.12l/kg using BrewMate.