What is the trick to partial boil ratios?

[Kungpaodog]

I went with two gallon boils on my first two batches, instead of the suggested 1.5, because I was concerned about losing too much water to boil-off. After reading some more threads, it seems that the more water in the boil, the more hops are utilized and the less chance I have of caramelizing my LME. But I still don't have a full understanding of what happens when you use more water for the boil.

How would it change my next recipe if I were to do a 3 gallon boil (the most I can do) instead of the suggested 1.5?

 

[BarleyWater]

Here ya go...

The Bigger the Boil, the Better the Boil
The maximum threshold of IBUs in a given batch of beer is 100, anything over that is only adding to flavor (and head retention and mouthfeel). This maximum number is also only in worts of around 1.050. Now if you are boiling 3 gal down to about 2.5, and adding 2.5 gal of wort, then your maximum is already sliced down to 50 IBUs in a batch, and that is still with a wort gravity of 1.050 or below.

Now, with a full boil if you are trying to reach a final gravity 1.050, then you will have near 100% efficiency when it come to alpha acid isomerization and IBU absorption, and you can reach the 100 IBU mark, since you would be starting the boil around 1.044. When using LME, this will be about 7 lbs. If you put 7 lbs of LME into only 3 gallons of wort, then you are starting with a pre boil gravity of 1.084, boiling down to probably around 2.5gal at 1.100 before topping of with water to reach your OG of 1.050. Far above the ideal IBU efficiency gravity. This will leave you with a wort that has a max IBU rating of approx. 82.7, not too bad, but wait. After topping off, you will have only 41.4 IBUs.

So without doing a late extract addition you maximum IBU level would be 41.4, not quite the hop bomb you may have thought you were making.

Now, if you add say, half at the end, lets see what that does. You pre boil gravity will be around 1.042 (very close to that of a full wort boil), and you will boil off around to about 2.5 gal at 1.050, perfect. So now you have 100 IBUs, top off and you are at you maximum of 50 IBUs, still not the hop bomb you thought, but better. If you are only adding 2 gal of top off water, then you max IBU will be 60, 1.5 gal and the max IBU is 70, 1 gal is 80, .5 gal is 90 and not topping off can get you the maximum IBU level of 100.

I have been using this a lot lately. I wrote it in another thread, but I belive it is applicable here.

 

[Grinder12000]

Most recipes use 2.5 gallon boil that I see. Then 1/2 g is sucked up by grain. In the book Brewing Classic Styles they suggest not worrying about how much hops and to use because it is something you just don't have to worry about at this stage of the game.

As for LME - I've done the math on every batch and it is basically about 1/3 of the LME goes in at the beginning making the PH proper and the rest I put in with 10 minutes.

I'll have to read BarleyWater's stuff once I get some coffee in me - looks interesting but a 5:58 I only make it so far LOL

 

[Loweface]

Bookmarked...

This could be very useful, thanks...

 

[homebrewer_99]

I use 1.5 to 2 gal boils.

Charlie P's TCJOHB has a hop utilization chart in it that basically says 1 gal of water and 1 lb malt gives you a gravity of 1.040. At this ratio the bitterness extraction from the hops are greatest.

I really recommend switching from LME to DME.

I add the remainder of the malt at the 45 min mark and steep for 15 mins. This reduces any carmelization.

 

[Grinder12000]

I'm going to have to let that rattle around a while BarleyWater.

Form what you are saying, partial boils is WAY WAY bad for hop utilization and it is impossible to make an good IPA with a partial boil ???

 

[homebrewer_99]

I'm going to have to let that rattle around a while BarleyWater.

Form what you are saying, partial boils is WAY WAY bad for hop utilization and it is impossible to make an good IPA with a partial boil ???

Only partially true.

If you do a 2 gal boil and add ALL your malt (say 5-6 lbs) the density/gravity of the wort is too high and the hops utilization will really suck.

The key for good hops utilization in a partial boil is keeping the water to malt ratio about 1:1.

 

[Yooper]

I'm going to have to let that rattle around a while BarleyWater.

Form what you are saying, partial boils is WAY WAY bad for hop utilization and it is impossible to make an good IPA with a partial boil ???

That is not the way I read that. You can make a good IPA with a partial boil. The problem is the SG of the wort- the higher the SG, the less hops utilization. That's why many do the late extract additions- for better hops utilization as well as for the lighter color and less carmelization.

In a full boil, you may boil 6 gallons down to 5 gallons. As you do this, the evaporative effect means that you SG is lower at the beginning of the boil, and higher at the end. So, your bittering hops will be added at the beginning, when the SG is the lowest. Still, it's not a huge difference, maybe a few points. As an example, let's use a OG of 1.067 for my finished 5 gallons. At six gallons, that SG will be around 1.061 or so when the boil starts. In this recipe (an English IPA), the IBUs are 50.

Same recipe, but with a partial boil of 2.5 gallons, the IBUs would be 23.5. You can see the remarkable difference in hops utilization.

However, that doesn't mean it's impossible to make a good IPA or hoppy beer. It just means you have to be aware of the limitations. You can add the extract with 15 minutes left in the boil. So, in my example, using 9 pounds of LME, I'd add half of the extract with 15 minutes left. That would give me 43 IBUs. If I added 3 pounds of LME at the beginning of the boil, and then the rest of the extract at the end, I'd get 51 IBUs. That's almost exactly the hops utilization of my full boil AG recipe.

 

[Grinder12000]

AHHH - ok - I see. I knew I Was doing it correctly but reading the words with my fuzzy brain this morning I was reading it the wrong way.

thanks - sorry for being fuzzy brain this morning - Golf banquette last night AND YOU KNOW WHAT THAT MEANS. Too many Spotted Cows!

 

[Kungpaodog]

Thanks, BarleyWater. That's a great explanation, I'll also re-read that bit in TCJOHB. Next step, hundreds more dollars in full boil equipment and wort chillers! (If I ever get un-broke)

 

[BarleyWater]

Next step, hundreds more dollars in full boil equipment and wort chillers! (If I ever get un-broke)

$30-$40 for a turkey fryer kit (burner and 7.5 gallon kettle), and another $30-$40 for the stuff to make an immersion chiller.

EDIT: Oh, yeah. Another $50 for a propane cylinder (after that it's only like $15 to refill, and it lasts several batches). Still, not hundreds, you could probably do it for just about $100 if you shop around.

 

[ChefBrew]

Great thread, I just had an issue with color on my last two (brew numbers 2&3) brews.
Prosted!!

 

[Lep]

whoops, wrong thread.

 

[WIP]

Here ya go...

The Bigger the Boil, the Better the Boil
The maximum threshold of IBUs in a given batch of beer is 100, anything over that is only adding to flavor (and head retention and mouthfeel). This maximum number is also only in worts of around 1.050. Now if you are boiling 3 gal down to about 2.5, and adding 2.5 gal of wort, then your maximum is already sliced down to 50 IBUs in a batch, and that is still with a wort gravity of 1.050 or below.

Now, with a full boil if you are trying to reach a final gravity 1.050, then you will have near 100% efficiency when it come to alpha acid isomerization and IBU absorption, and you can reach the 100 IBU mark, since you would be starting the boil around 1.044. When using LME, this will be about 7 lbs. If you put 7 lbs of LME into only 3 gallons of wort, then you are starting with a pre boil gravity of 1.084, boiling down to probably around 2.5gal at 1.100 before topping of with water to reach your OG of 1.050. Far above the ideal IBU efficiency gravity. This will leave you with a wort that has a max IBU rating of approx. 82.7, not too bad, but wait. After topping off, you will have only 41.4 IBUs.

So without doing a late extract addition you maximum IBU level would be 41.4, not quite the hop bomb you may have thought you were making.

Now, if you add say, half at the end, lets see what that does. You pre boil gravity will be around 1.042 (very close to that of a full wort boil), and you will boil off around to about 2.5 gal at 1.050, perfect. So now you have 100 IBUs, top off and you are at you maximum of 50 IBUs, still not the hop bomb you thought, but better. If you are only adding 2 gal of top off water, then you max IBU will be 60, 1.5 gal and the max IBU is 70, 1 gal is 80, .5 gal is 90 and not topping off can get you the maximum IBU level of 100.

I have been using this a lot lately. I wrote it in another thread, but I belive it is applicable here.

Thread revival!

Where did this quote come from?