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Batch size - Poor

McTap

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G'day there. I've got an American Pale Ale recipe that tastes delicious but for some reason a 27 litre batch has ended up as 23 and now 21. I've hit the target original gravity of 1.052 both times but where is the rest of it? What's going on?!!

6.2 Kg Grain + 19L water (sparge with 25L@75c) - 64c mash 75min

Pre-boil vol 31.7L (1.040)

21L into fermenter (OG 1.052)

Any help would be most appreciated!! I'm using a 60L mash tun (cooler) and a 70L boiler (copper ex-dairy).

ps. I tried tailoring my own equipment profile but Beersmith told me to mash 6.2Kg with 11L (= thick porridge) so I used the standard 10G cooler profile and 'edited' the mash step to 19L.

 
McTap said:
G'day there. I've got an American Pale Ale recipe that tastes delicious but for some reason a 27 litre batch has ended up as 23 and now 21. I've hit the target original gravity of 1.052 both times but where is the rest of it? What's going on?!!

6.2 Kg Grain + 19L water (sparge with 25L@75c) - 64c mash 75min

Pre-boil vol 31.7L (1.040)

21L into fermenter (OG 1.052)

Any help would be most appreciated!! I'm using a 60L mash tun (cooler) and a 70L boiler (copper ex-dairy).

ps. I tried tailoring my own equipment profile but Beersmith told me to mash 6.2Kg with 11L (= thick porridge) so I used the standard 10G cooler profile and 'edited' the mash step to 19L.

Are you consistent in your pre-boil figures, both volume and gravity? 

For your equipment profile, you specify the sizes and losses in the system.  When it comes to the water volumes for mashing, you can edit your mash profile and set the water to grain ratio to where you want it, such as you did and then save that profile to use for other recipes.
 
How much wort is lost between the kettle and the fermenter?

If you had identical gravity but differing volumes, then there may be a mash efficiency issue. Your target suggests that you have a Brewhouse Efficiency of 71 or 72%. Is that correct? Is that what you're expecting for mash efficiency (different from Brewhouse)?

Your actual yield suggests that the Brewhouse Efficiency is 55 to 60%.

You have a whopping 34% difference between starting boil volume and your fermenter yield. The target of 27 liters is about 15%, which is normal boil off. That leaves 4 to 6 liters, which seems to be the loss to trub.

Try setting your equipment profile for 60% Brewhouse Efficiency, with 5 liters loss to trub. Look on the Mash Tab at the estimated mash efficiency, it should be pretty close to your expectations (~72%). The gravity in the recipe will drop, which naturally means you'll need more grain to make up the additional volume.
 
Cheers guys..

Same 27 litre batch size on Beersmith, same 6.2 Kg grain.

Brew a)
total water 45.47L
Pre boil vol: 35.2 measured @ 1.040
23.3L into fermenter @ 1.052

Brew b)
total water 43.7L
Pre boil vol: 31.7 measured @ 1.040
21L into fermenter @ 1.052

There would be approximately 2-3L of hoppy sludge left in the kettle. Thanks for the advice re: efficiency - it's still a grey area...
 
McTap said:
There would be approximately 2-3L of hoppy sludge left in the kettle.

Hmmm. That's half of what I calculated. Have you measured this?

The difference must then like in your boil off. It seems to be much higher than you've put into BeerSmith.

You haven't said if your preboil gravity is correct or lower than BeerSmith calculates. Now it seems like that would be on the low side?

I came up with my numbers based on your post boil gravity and volume. It seemed consistent with your grain weight and preboil volume. If you have less trub, then your mash efficiency is much lower.
 
Thanks for the reply. The pre-boil gravity was a bit low. 1.044 target / 1.040 measured. I am suspicious of the boil off though, it's quite a wide kettle with decent power, however the OG is turning out correct so I'm not sure what to do there. Cheers.
 
McTap said:
the OG is turning out correct so I'm not sure what to do there. Cheers.

So, what you're aiming for is 27 liters at 1.052 OG. All of the replies above are telling you the answer, but let's put it together, anyway.

The first thing is to apply your real world results to the equipment profile you're using. The second thing is to be more consistent about your production.  ...Or just live with a delicious beer, with no care for volume.  ;)

Based on Gravity points, you're consistently right around 3.58 l of trub.
Your stats say you're consistent about your pre and post boil gravity.

Everything else is variable, but shouldn't be.

Boiloff:
Recipe 1: 23.6%
Recipe 2: 22.4%

This is a tolerable difference, but represents much more than you need if it's a 60 minute boil. Somewhere closer to 12 to 15% is normal in 60 minutes. Your equipment profile is probably in that range. This is a significant part of your lost volume.

Mash Efficiency:
Recipe 1: 71.68%
Recipe 2: 64.44%

These are low extraction numbers for most types of mash and sparge methods. You may need to mill more tightly and/or monitor and adjust your mash pH.

Brewhouse Yield:
Recipe 1: 86.67%
Recipe 2: 85.43%

This is the percentage of post boil volume that gets to your fermenter. This is NOT the same as Brewhouse Efficiency, but it is a factor.

Brewhouse Efficiency:
This is the mash percentage multiplied by the yield percentage.
Recipe 1: 0.7168 * 0.8667 = 0.6328 = 63.28%
Recipe 2: 0.6444 * 0.8543 = 0.5505 = 55.05%

So, now we know how you got your volume and gravity from 6.2 kg of malt. The next question is what amount of malt you'll need to get 27 liters at 1.052, right?

Since we know the trub amount is constant, we use that to figure the Brewhouse Yield. Dividing the 27 liter yield by the 30.58 kettle volume, we get ....?    ....Anyone?

Right! 88.29% yield.  Multiply that by the lower of the two mash efficiencies and we get 56.9% Brewhouse Efficiency. This is now how you'll discover the malt required to reach 1.052.

Differing malts have differing extract yields. BeerSmith calculates each malt separately, then uses your equipment profile and Brewhouse Efficiency number to calculate the OG.

Using a rough calculation, I think you'll need 9.25 to 9.5 kg of malt to reach your goal.
 
Brewfun, EXCELLENT reply, much appreciated. Thanks everyone.
 
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