2.5 gallon batch Help!!

[RothRock]

As title says I am doing a Brewers Best partial mash kit this saturday and it's a Holiday Ale.
Now this is a 5 gallon kit and I want to split the kit and make 2.5 gallons. My question is since I am making half the kit do I just split everything in half (grains, malt extract, hops, speciality grains, yeast and spices). Thanks guys.

 

[acidrain]

The easy answer is yes, just split it.
In reality recipes don't scale that way. Hop utilisation scales differently from the malts. They are such small differences though. For your purposes it will be fine.
When you get around to brewing the second half, you may want to tweak it a bit anyway.

 

[RothRock]

Thank you sir...

 

[Singletrack]

The easy answer is yes, just split it.
In reality recipes don't scale that way. Hop utilisation scales differently from the malts. They are such small differences though. For your purposes it will be fine.
When you get around to brewing the second half, you may want to tweak it a bit anyway.

Hmmm, I'd like to challenge that hop utilization statement, without saying it is wrong. Seems utilization should be the same if you keep the same preboil and post boil gravity and same boil time. The only thing that would seem to change is the boil-off (as a percent of final volume), with minor impact on pre-boil gravity. Can anyone confirm or deny?

 

[acidrain]

It's why there is a scaling feature in Beersmith... if you scale a recipe you will see that it's not linear. It also factors in the losses.

 

[Singletrack]

It's why there is a scaling feature in Beersmith... if you scale a recipe you will see that it's not linear. It also factors in the losses.

I don't use BS, so I'll take your word. So if he uses a smaller, narrower pot and reduces boil-off by half, then hop utilization would be the same?

 

[ron,ar]

I have done several...er lots of small batches and have had good luck just using simple math to get the right proportions. Having said that, I am no expert in hop utilization and it may be an issue, even if it is a small one. Of bigger concern to me is boil off loss.
Once you reach a rolling boil, it doesn't matter if there is 3 gallons or 7.5 gallons in that kettle, the loss will basically be the same. Make sure you start with enough wort to cover the loss. BTDT....my first 3 gallon batch started as a 3 gallon but ended as a 2 gallon batch.

 

[Singletrack]

I don't use BS, so I'll take your word. So if he uses a smaller, narrower pot and reduces boil-off by half, then hop utilization would be the same?

Well Singletrack, let me take a few moments to provide a thorough answer to this question.

If you cut all the ingredients in half, and if you transfer the entire volume of your BK to the fermenter, then yes, you are correct: if you could also reduce your boil-off volume to half, then there would be no change in the calculated IBUs.

However, you know it may be very difficult to halve your boil-off volume, and that will result in a lower pre-boil gravity, since you will need a higher percentage of water pre-boil. And that lower gravity means higher hop utilization, which leads to more IBUs. How much more? Glad you asked. For the Belgian dubbel that I will be brewing this weekend, I calculated IBU=25.3 for the full recipe, and IBU=26.4 for the half recipe. Could you detect that 1 IBU difference? I know I could not.

But wait. Maybe you do NOT dump the entire volume of your BK into the fermenter. As the founding (and sole) member of BETH -- Brewers for the Ethical Treatment of Hops -- I insist on free range hops in the BK, so yeah, I leave some sludge in the BK. In this case, we have more to worry about than IBUs. For that dubbel mentioned previously, the full recipe had an OG of 1.072, and used a BK loss volume of 0.5 gal. (Don't judge me for my out-of-style "dubbel.") If I use the same 0.5 gal loss for the half recipe, the OG is only 1.067. This is a little different beer. But you should be able to cut the BK loss in half to solve this problem. Then, the IBUs will be very close again too.

So there you go. Just do what acidrain said to begin with! But cut the BK loss in half and use a smaller pot to reduce boil-off if possible.

 

[johnsant]

Why not just make the whole 5 gal boil and then split into 2 different fermenters. us the yeast you were going to use in one bucket and get another yeast to see what the difference is in another bucket.

 

[Yooper]

Well Singletrack, let me take a few moments to provide a thorough answer to this question.

If you cut all the ingredients in half, and if you transfer the entire volume of your BK to the fermenter, then yes, you are correct: if you could also reduce your boil-off volume to half, then there would be no change in the calculated IBUs.

However, you know it may be very difficult to halve your boil-off volume, and that will result in a lower pre-boil gravity, since you will need a higher percentage of water pre-boil. And that lower gravity means higher hop utilization, which leads to more IBUs. How much more? Glad you asked. For the Belgian dubbel that I will be brewing this weekend, I calculated IBU=25.3 for the full recipe, and IBU=26.4 for the half recipe. Could you detect that 1 IBU difference? I know I could not.

But wait. Maybe you do NOT dump the entire volume of your BK into the fermenter. As the founding (and sole) member of BETH -- Brewers for the Ethical Treatment of Hops -- I insist on free range hops in the BK, so yeah, I leave some sludge in the BK. In this case, we have more to worry about than IBUs. For that dubbel mentioned previously, the full recipe had an OG of 1.072, and used a BK loss volume of 0.5 gal. (Don't judge me for my out-of-style "dubbel.") If I use the same 0.5 gal loss for the half recipe, the OG is only 1.067. This is a little different beer. But you should be able to cut the BK loss in half to solve this problem. Then, the IBUs will be very close again too.

So there you go. Just do what acidrain said to begin with! But cut the BK loss in half and use a smaller pot to reduce boil-off if possible.

Yes, all that I think (didn't read too closely) except for the "reduce boil off if possible" part. you do not want to do that. Your boil off is your boil off. You don't need to reduce it.

IBUs are independent of wort gravity, so let that part go. Just brew the beer, and the boil off is what it is, and the beer will be great.

 

[Singletrack]

Yes, all that I think (didn't read too closely) except for the "reduce boil off if possible" part. you do not want to do that. Your boil off is your boil off. You don't need to reduce it.

IBUs are independent of wort gravity, so let that part go. Just brew the beer, and the boil off is what it is, and the beer will be great.

I use the Tinseth formula for IBU. IBU is not independent of gravity in this formula, though it seemed to make only a small difference. Why not use a smaller pot for a half batch? Brewers go to the trouble to get a pot with 1.2 ratio. Doesn't help if you fill it 25% full.

 

[RothRock]

I ended up brewing the whole 5 gallons. I felt with it being my first partial mash that I should get the hang of it first before I start manipulating recipes.
So far it is a very active fermentation, I am excited to bottle this beer.