Halving Receipes

[ben_sa]

Hey guys,

Since ive acquired a couple of 9l kegs recently, Im planning on knocking up a couple of (different) half batches.

I still extract brew with spec. grains etc. No AG/BIAB yet!

Is it as simple as taking a recipe and splitting the malt/grain/hop bill in half? Ill aim for 11.5l brews which will fill the keg and leave some space for trub and other crap...

As for the boil... Again, Just half?

So something along these lines:

1.25kg LDME
100g pale crystal steeped
10g Chinook 60min
12.5g cascade 15min
12.5g cascade 0min
1/2 sachet US05/Nott

Seep grains at 65-70.c for half hour as usual
add steepings and water upto 3l boil volume along with 500g DME
Hop additions as noted?

Or am i way off track, and would i need to scale down the hops in a different way?

I have beermate at home, But alas, my home pc is currently getting upgraded and my work computer wont allow me to install it :angry:

Cheers for any advice.
Ben

EDIT: I did try and search "scaling down recipes/recipe scale down" to no avail :-\

 

[yum beer]

Seems fine to me

Brewmate gives OG 1043
Fg 1011
IBU 29

 

[manticle]

One thing to keep in mind is evaporation. If you lose 4 litres per hour (for example) that leaves 18 L from a 22 L preboil. If you boil 11 litres with the same intensity for the same time, you will end up with 7 litres.

That will affect your final figures.

If you know your evaporation rate you can either: not worry as it may not be significant in your case

OR

top up with water as you go to keep the volume proportion roughly the same.

 

[jotaigna]

One thing to keep in mind is evaporation. If you lose 4 litres per hour (for example) that leaves 18 L from a 22 L preboil. If you boil 11 litres with the same intensity for the same time, you will end up with 7 litres.

That will affect your final figures.

If you know your evaporation rate you can either: not worry as it may not be significant in your case

OR

top up with water as you go to keep the volume proportion roughly the same.

all good info above.
as for the boil, still you need to take the same amount of time. When doing half batches you can chuck all your fermentables at the beginning rather than doing late additions(common practice for extract brewers with small pots like me)
most brewing software calculates hop utilization and such without considering late fermentable additions so from the point of view of formulating recipes is less finicky.

 

[ben_sa]

Ah thanks guys... If i threw all the fermentable in (all the DME) wouldnt this affect the hopping schedule... I was under the impression the reason only 1/3 (roughly) was added to the boil was to determine OG... If i bang the entire 1.25kg in, wouldnt this affect the bittering/flavour?

I stupidly forgot to take down my evap figures last time, Which i should have!! Maybe ill go with about a 4L boil, Im not using a ridiculous burner so its a fairly gentle roll i get going...

 

[MHB]

How you tackle recipe rescaling is going to depend on a couple of factors, as mentioned above evaporation as a proportion of the wort gets bigger in smaller batches, the big one is your system loss. If at the end of the boil you has 26 L in the kettle and you knocked out 23 of that to the fermenter your (post kettle) system loss is 3 L, clearly if you were going to make 13 L (in fermenter) you would need 16 L at end of boil and 16 isnt half of 26. You need to look at your system and see how much you lose and make allowances accordingly.
System loss is really only going to be important for small breweries making big changes (in the example above its 100%).
there are a couple of other factors like bigger kettles tend to get more out of the hops and bigger mash tuns tend to yield proportionally more extract, these wont be so noticeable at a small scale so I wouldnt be mucking around with my calculations too much, just watch the losses.
The other option being to make your normal size batch and no-chill half, 10 L plastic food grade jerry cans only cost about $10 and you could try the same wort with different yeast or try some different dry hopping on a wort that you know is the same. Good way to learn what different hops and yeast do to a wort.
MHB

 

[manticle]

Gravity will affect hop utilisation. Best to keep the boil of a to-be-diluted wort between 1030 and 1050 and add the rest of the fermentables in towards the end. You can add in at the beginning but you will need to use a lot more hops if the gravity sits any higher (as it will if you are using extract to make a concentrated wort which is diluted to full volume).

However, if you are boiling full volume with no dilution, you might be best off sticking with recipe calcs as is and adding everything together. Hopefully that makes sense - if not, I'll try again.

 

[ben_sa]

That does make sense guys. Thanks guys

I didnt honestly think to make the full recipe, then simply chill half, and use half. I reckon that will be the safest way to go as this is one of my usual recipes.

Once the boil is complete, i gather i measure the total volume, add half of post boil wort to the cube, half to fermenter, then fill both to 11.5L, one half to the fridge, one to the fermenter with yeast (once cool) and roberts your mothers brother?

This time ill measure the total evaporation from the 6L boil. AND TAKE NOTES!
Cheers again!

 

[manticle]

MHB is suggesting no-chill for the second half. If you no-chill properly, you can keep the wort indefinitely without yeast. If you chill it, you will need to add yeast fairly quickly or it is breeding ground for other micro-organaisms.

No-chilling half is a great idea but may be difficult if you don't have a tap on your pot. Alternatively you could do as MHB suggests but put one half in fermenter 1 with X yeast and one in another fermenter with Y yeast. Fermenters aren't much more expensive than cubes and you can buy 15L ones.