Full boil, Aluminum brewpot

fatbob · 03-01-2009, 11:20 PM

I was told before I started brewing that aluminum pots should not be used, however after doing a search on aluminum, I plan on using the aluminum pot that came with my turkey fryer.
I have been using a 20 qt. SS pot to do partial boils & adding all of the extract in the beginning.
After boiling water in the aluminum pot to form the oxide layer in it I will be able to do full boils. I plan to split my LME addition & put half at the start of the boil & then add the other half towards the end of the boil.
I'm thinking that with the late addition lowering the IBU'S, And the Full boil adding to the IBU'S, between the two it should balance out. Am I on the right track.

**Greyhound** · 03-01-2009, 11:23 PM

I'm new too, but let's see if the good folks on this forum taught me well...

Late addition will increase IBU's as hop utilization is increased with the lower gravity wort; same reason your full boil will increase IBU's.

**jkarp** · 03-02-2009, 02:48 PM

Late addtion may increase utilization if there's correspondingly less hot break to precipitate out iso-alpha. The wort gravity itself has no direct impact on utilization. Minor but significant distinction.

**pompeiisneaks** · 03-02-2009, 02:50 PM

The aluminum pot myth is in one of the forums stickies... Basically its a way for dishonest LHBS to get you to buy significantly more expensive stainless pots. You should look and read it.... I think its "equipment/sanitation" but not sure...

I've no clue on the IBU's though, but what Greyhound and jkarp said seems to be on point.

**mmb** · 03-02-2009, 03:02 PM

Quote:

Originally Posted by jkarp

Late addtion may increase utilization if there's correspondingly less hot break to precipitate out iso-alpha. The wort gravity itself has no direct impact on utilization. Minor but significant distinction.

Umm supporting documentation? Wort Gravity in the boil does have a direct impact on utilization and it is something that is factored into the IBU calculation formulas that brewers use. I use Rager which has a compensation for gravities over 1.050.

Since a partial boil so much higher in gravity than a full boil, late extraction makes a big difference. When you get to full boil volumes the benefits of late extract additions lean more towards prevent color reactions in the boil for light colored beer styles.

Code:

IBU  = (OUNCES OF HOPS) * %UTILIZATION * %ALPHA * 7462
       -------------------------------------------------
                 VOLUME(gallons) * (1 + GA)

OG < 1.050

GA = (BOIL_GRAVITY - 1.050)
     ----------------------
             0.2

otherwise,

GA = 0

Based of the following Utilization table

Code:

Boiling Time (minutes) %Utilization
-----------------------------------
 0 -  5                       5.0
 6 - 10                       6.0
11 - 15                       8.0
16 - 20                      10.1
21 - 25                      12.1
26 - 30                      15.3
31 - 35                      18.8
36 - 40                      22.8
41 - 45                      26.9

**jkarp** · 03-02-2009, 03:07 PM

Quote:

Originally Posted by mmb

Umm supporting documentation?

It's been beaten to death here in many threads, or listen to Palmer discuss in his own words on the 03/20/08 Basic Brewing.

snailsongs · 03-02-2009, 03:12 PM

The basic principle with Hop utilization and wort gravity is that the alpha acids are utilized more efficiently in a thinner, more watery boil than a thicker more viscous boil. Hence, a late addition increases utilization of the bittering hops.

**jkarp** · 03-02-2009, 03:15 PM

Quote:

Originally Posted by snailsongs

The basic principle with Hop utilization and wort gravity is that the alpha acids are utilized more efficiently in a thinner, more watery boil than a thicker more viscous boil. Hence, a late addition increases utilization of the bittering hops.

Actually, there's a lot more to it than that. Listen to John Palmer's report.

**mmb** · 03-02-2009, 03:28 PM

Quote:

Originally Posted by jkarp

It's been beaten to death here in many threads, or listen to Palmer discuss in his own words on the 03/20/08 Basic Brewing.

Please read Palmer's BYO article "Behind the IPU: Advanced Brewing" from the March/April 08 BYo, also available online at
Brew Your Own: The How-To Homebrew Beer Magazine - Story Index - Hops - Behind the IBU: Advanced Brewing.

Yes, there is a lot more to the calculation of IBU in a wort, but unless everyone has spectrometers in their garage then taking the amount of AA%, boil time and wort gravity then IBU levels should be comparable with fresh hops.

My issue was the statement that

Quote:

Originally Posted by jkarp

The wort gravity itself has no direct impact on utilization.

Even Palmer's recent "come to Jesus" moment doesn't change viscosity or OG effecting solubility in a solution.

**jkarp** · 03-02-2009, 03:43 PM

I love how every time this topic comes up on HBT it's like telling a 7yo there's no Santa

Brewing knowledge evolves. Homebrewers will come around eventually. There's nothing wrong with my statement - it's Palmer's as well. Palmer has said even though the gravity based IBU formulas are wrong, they're "good enough". Are they? Time and testing will eventually tell. Perhaps we'll see new, more accurate IBU models in the future. In the meantime, homebrewer's shouldn't take these numbers too seriously. That's the ultimate takeaway point.

Now, we've pulled the OP's aluminum Q far enough OT.