Full boil on a extract batch

So I've searched this topic and i'm finding very incosiestent results. I have a brewers best american cream ale kit laying around and I figured I'd brew up a extract kit instead of breaking out all the AG gear since my schedule is busy.

Since I have the equipment I'd like to do a full boil for better hop utlization and less harshness in the malt. Is there a formula to cut back the hops to get the same IBUs? Also, do I follow the LME, DME, dextrose additions per receipe or adjust that too?

Heres the ingredients

BOIL SIZE: 2.5

FERMENTABLES
3.3 lb. Extra Light LME 60 min
2.0 lb. Pilsen DME 20 min
1 lb. Corn Sugar 20 min


HOPS
1.25 oz. willamette Bittering 60 min
1 oz. willamette Aroma 10 min

Top off to 5 Gallons
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As stated above I want to do a 5 gallon boil, not the 2.5 gallon.

You don't need to adjust the hops, really. But you could if the bittering hops you have are a higher AAU than you want for your bittering.

It used to be thought that hops utilization was impacted by wort gravity, but it's been proven wrong. What does impact the IBUs, though is "topping off". So, if you have 2.5 gallons of 50 IBU wort, and add 2.5 gallons of water (0 IBUs) the IBUs will be halved.

For a cream ale, I'd probably target 15-20 IBUs, so 1.25 ounce of bittering hops may be too much for either a full boil OR a partial boil, depending on the hops.

Oh, I'm sorry I just realised I didnt mention that. They are both willamette additons. Just to add, they receipe shown is for a 2.5 gallon boil. Which I want to do a 5 gallon boil with. So essentially, by the logic given, I should half my hop additions on a full boil since the IBUS would be havled if i were to follow the directions?

If gravity doesn't matter, I suppose I could just use beer smith as if I were doing a AG batch, just to see what IBU range I'm in?

Yooper said:

It used to be thought that hops utilization was impacted by wort gravity, but it's been proven wrong.

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When did this happen? I was under the impression that adding only some extract at the beginning of a partial boil would help boost IBUs to compensate for the top-off water.

info on hop utilization is here:
http://www.howtobrew.com/section1/chapter5-5.html

[deleted misinformation...sorry for confusion!!]

Quote from the section of Palmer's book that you linked:

As you will see in the next section, hop utilization decreases with increasing wort gravity. The higher concentration of sugars makes it more difficult for the isomerized alpha acids to dissolve.

So, the more watery (as far as gravity goes) the boil, the BETTER the hop utilization.

And yet again as stated before the confusion and contradicting answers continue.. more over, my dilemma also is that I'm adding fermentables at different times.. my gravity from 60-20 is different from 20-flameout. Not to mention boil off rate which will constantly change the gravity as well.

To be honest its getting way over thought in my opinion.

Adrenaline-Junkie said:

To be honest its getting way over thought in my opinion.

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Agreed, have a simplistic answer? Is it as easy to just say half the hops if doing a full boil instead of topping off?

VampireSix said:

Quote from the section of Palmer's book that you linked:

As you will see in the next section, hop utilization decreases with increasing wort gravity. The higher concentration of sugars makes it more difficult for the isomerized alpha acids to dissolve.

So, the more watery (as far as gravity goes) the boil, the BETTER the hop utilization.

Click to expand...

His book is outdated. In about 2008, he came out and said he "got it wrong' in How to Brew, and that he knows that utilization is indeed independent of wort gravity. There are more updated podcasts and writings by Palmer concerning this.

steber said:

Agreed, have a simplistic answer? Is it as easy to just say half the hops if doing a full boil instead of topping off?

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No. Reduce them by 20% if you feel you have to do something, otherwise don't adjust.

It makes you wonder if you could just boil your hops in a separate pot of water. Heck, mash, steep, boil each grain separately. Then just mix it all together at the end.

You'd think he'd change his website if the current theory is different...ah well.

Ive actually thought about that before. Really, for extract kits, yo could probably get away with basic pots and stuff youd normally have at home and just dump it together.