First BIAB - disastrous! :(

[dangloverenator]

Hey there.

So following the many good tutorials on BIAB, I decided to give it a go using my own recipe for a black RyePA. I'm afraid the grain measurements are in kg, but I've done my best to convert them for the benefit of US forummers...

Here's the log I kept on BrewMate: (note it's a super small batch - 5l, or about 1.1 gallons)

Black RyePA NB/W/C - 08.02.12
Target OG: 1.068
Target FG: 1.017
Target ABV: 6.7%
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Brewday log
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1kg Maris Otter (=2.2lb) = 60.61%
300g Crystal (=0.66lb) = 18.18%
250g Rye (=0.55lb) = 15.15%
100g Black patent (=0.22lb) = 6.06%

Mashed at 66C for 90 minutes.
Mashout at 75C for 10 minutes

SG before boil - 1.051 @ 75C (I measured this in order to try and get an efficiency value at the end of the brew, this seems low, but the wort looked and tasted ok)

Boil for 60 minutes
0.3oz Northern Brewer @ 60
0.2oz Willamette @ 45
0.2oz Willamette @ 30
0.2oz Cascade @ 10
0.6oz Cascade @ flameout

SG after boil - 1.089 (MASSIVE!?!?!)

Transfer to FV very problematic - couldn't start siphon, wort too thick. Eventually tried to strain without a funnel (I know...), then decided just to pour it in, lost a lot of wort in the process. Topped up with cold water to approx. 5l. Yeast pitched dry.
-----------------------------

So obviously the straining thing wasn't a brilliant idea, and i will make sure I have a proper strainer and funnel set up next time. But this doesn't explain the insane consistency or really high OG. Was it just too much malt for such a small batch? Did I just not squeeze the bag enough? Should I sparge next time? Any advice would be great, I feel like I may have done something very stupid...

 

[RM-MN]

What is probably the main problem is that you didn't account for the amount of water you boiled off. Couple that with the fact that rye makes a very sticky wort and you get a very high gravity, sticky mess. Try this again sometime with less rye in the mash and watch your water level, adding extra water if necessary.

 

[dangloverenator]

That was my first thought too, but I started with 6.8l of strike water, which I assumed would be enough? Do you think maybe I just left too much water in the grain bag? I didn't want to squeeze it too much to avoid extracting tannin, but is that a misnomer?

 

[weirdboy]

Try using some rice hulls next time you brew with wheat, rye, or really any grain that doesn't have husks.


I am confused by the gravity thing. What was your preboil volume, and post-boil volume? That is the determining factor. From what you said my guess would be something like 8 liters preboil and 5 liters post-boil?

As mentioned, boil-off rate is a huge factor, especially when you are doing small batches. You are likely to boil off 50% or more of the preboil volume in a 60 minute boil. What you ought to do is just perform a test. Put exactly 10 liters of water in your pot, bring it to a boil for an hour just as vigorous as you would for a beer, cool it down, and measure how much water is left. That is your boil-off rate.

Then, you also need to account for losses to trub/etc. Again, this becomes quite a lot more significant when you are brewing only a few liters of beer. Normally it's maybe 5% of your volume at most, but for a small batch like that it could be as much as 25-50%. Try to get an idea how much this is on your system, and account for it when you design/scale your recipes.

 

[frontenac]

If the grain weights are accurate and your final volume was truly 1.1 gallons, it looks to me like you got about 73? efficiency. Pretty average for an all-grain batch. So, in my opinion, yes it was probably too much malt for the target gravity.

 

[RM-MN]

That was my first thought too, but I started with 6.8l of strike water, which I assumed would be enough? Do you think maybe I just left too much water in the grain bag? I didn't want to squeeze it too much to avoid extracting tannin, but is that a misnomer?

You cannot extract tannins by squeezing the grain bag. It takes two conditions that have to happen together, the temperature of the wort has to be above 170 and the pH of the mash has to be over 6. I'm pretty sure neither of those happened so tannins are not a worry.

Wort left in the grain bag makes part of the story but you probably boiled off more than you anticipated. It happened to me today. Both of us should have added top off water.

 

[Ambrose_Balin]

The equation that matters here:

(pre-boil volume) X (pre-boil gravity) = (post-boil volume) X (post-boil gravity)

Measuring your preboil volume / gravity allows you to calculate what volume to boil down to in order to hit your intended OG. If you are under density then boil a bit longer, adding hops appropriately later. If you are over gravity, add more runnings by dunking your bag another time and squeezing. You will have to up the hops a *little* to keep the balance exactly what it was, but the changes described here are pretty minute so I don't usually bother.

You can also pretty accurately predict what your preboil gravity is going to be before the mash by estimating a safe percentage for your mash (70%?) and multiplying the extract potential of your grains by their relative contributions, adding them together, and multiplying the whole sum by your expected efficiency.

The amount your preboil gravity will be off is going to be small enough to be manageable even if your efficiency is off by 5% in either direction by adjusting your boil slightly.

Getting this stuff down will allow you to more consistently brew the same beer over and over despite some variability in your mash efficiency.

 

[dangloverenator]

Thanks for all your help!

As mentioned, boil-off rate is a huge factor, especially when you are doing small batches. You are likely to boil off 50% or more of the preboil volume in a 60 minute boil. What you ought to do is just perform a test. Put exactly 10 liters of water in your pot, bring it to a boil for an hour just as vigorous as you would for a beer, cool it down, and measure how much water is left. That is your boil-off rate.

Will definitely do this, but can you tell me how exactly to do that? Say I boil 10 litres and end up with 7 left, does that mean I will lose 3 litres every time, or 30%?

(pre-boil volume) X (pre-boil gravity) = (post-boil volume) X (post-boil gravity)

Another potentially stupid question... how do I calculate the pre-boil volume? Is that just the volume of strike water, or the total volume including the grain?

 

[tre9er]

Thanks for all your help!
stupid question... how do I calculate the pre-boil volume? Is that just the volume of strike water, or the total volume including the grain?

The volume of liquid in the BK, including any mash and sparge runnings.

 

[tennesseean_87]

That was my first thought too, but I started with 6.8l of strike water, which I assumed would be enough? Do you think maybe I just left too much water in the grain bag? I didn't want to squeeze it too much to avoid extracting tannin, but is that a misnomer?

As stated, it's a myth that squeezing extracts tannins. It is not a misnomer, however.

Then, you also need to account for losses to trub/etc. Again, this becomes quite a lot more significant when you are brewing only a few liters of beer. Normally it's maybe 5% of your volume at most, but for a small batch like that it could be as much as 25-50%. Try to get an idea how much this is on your system, and account for it when you design/scale your recipes.

Why would this be the case? Wouldn't the use of less hops and less grain mean less break material and hop matter? It would make sense to have more trub with higher gravity brews (5% trub loss for 1.050 batch; 8% loss for 1.080 batch), but if everything were scaled down I would think the trub would scale down as well, but maybe I'm missing something.

Wort left in the grain bag makes part of the story but you probably boiled off more than you anticipated. It happened to me today. Both of us should have added top off water.

I know DeathBrewer has topped up after fermenting and said he had no ill effects. He mentioned this in either his BIAB or Partial Mash thread. Maybe you can do that, though your hop utilization might be a bit off.

 

[weirdboy]

Will definitely do this, but can you tell me how exactly to do that? Say I boil 10 litres and end up with 7 left, does that mean I will lose 3 litres every time, or 30%?

If you are using Beersmith, I think this still forces you to put in a % volume rate, which I think is stupid, personally. For small batches especially, this number is often way different than for a regular batch. I tend to think of the boil-off rate as just gallons/hour or in your case liters/hour. Then if I know my target final volume, I can work backwards from there and add back in dead space/trub losses and boil-off volume to get my target preboil volume. So for you that would be, say, 3 liters per hour. If you do a recipe with pilsner malt and want to boil it for 90 minutes, that would be 4.5 liters that you'd lose during the boil.

Why would this be the case? Wouldn't the use of less hops and less grain mean less break material and hop matter? It would make sense to have more trub with higher gravity brews (5% trub loss for 1.050 batch; 8% loss for 1.080 batch), but if everything were scaled down I would think the trub would scale down as well, but maybe I'm missing something.

Well the actual amount of trub will probably decrease somewhat linearly with the size of the batch, but there is a limit as to how much you can siphon off before you start getting a ton of gunk in your beer, and how much other dead space you have in e.g. your hoses. That tends to be the same regardless of the size of the batch. Same goes for the yeast cake, dry hops, etc. In my case I figure I probably lose somewhere between .25 and .5 gallons per batch in losses like that between racking from the boil kettle through packaging, and more if it is a beer with a lot of hops in it. I have one beer I make where I probably lose more like a gallon from all the hops additions.

On my first "small batch" experiment, I noticed that I was losing a pretty hefty amount of the final volume due to stuff like this. I have since compensated for these losses when I do smaller batches.

 

[tennesseean_87]

I got it. The dead space losses are constant, but mean a higher percentage on a smaller batch. That's why I dump everything in the fermenter and let it settle out. No loses in hoses, kettle, and I can crash cool on the porch this time of year so that crap doesn't end up in bottles.

 

[dangloverenator]

Thanks for all the advice, guys! Based on what you said, this morning I ran a test boil of 5l of water, and ended up with only 2.1l left!! Taking this into account, I'm formulating my next recipe, a straight-forward American Pale/IPA. This is the plan so far...

1kg Maris Otter Pale
200g Crystal

Mash for 90 mins with 4l of water at 66C.
Dunk sparge with 4.7l of water at 75C
= 7.7l wort volume before boil (according to BrewMate, but surely that should actually be 8.7?? Where does that extra litre go??)

Boil for 60 mins, which, based on today's experiment, should hopefully leave me with around 5l of wort.

Apologies for the metric units! Thoughts??

 

[BigRob]

~1L absorbed by grains.

 

[dangloverenator]

~1L absorbed by grains.

Ah, probably should have realised that... If I squeeze the bag should I factor in a lower estimate? 1l seems a lot.

 

[BigRob]

I tend to run 1L/kg absorbed in my BIAB setup, and I squeeze the bag, once the squeezing starts to get me a thin trickle I'll stop it though.