IPA Recipe, sanity check

[kgg_033]

The last time i brewed an IPA, I was IBU gun-shy.
Any feedback on this sucker would be appreciated!

Boil Gravity of 3.75 gallons
Batch Size of 5.5 gallons (given the hops, I suspect about 4.8 - 5 gallon actual yeild at bottling)

8.25 lbs of Briess Golden light DME
10 oz Crystal 40
4 oz Aromatic Malt
4 oz Malto Dextrine Powder (for body/mouthfeel)
Hops - all are pellets
1 oz Magnum Hops 13.5% AA - Bittering, 60 min boil time
1 oz Cascade Hops 7.1% AA - Aroma/Flavor, 30 min boil time
1 oz Cascade Hops 7.1% AA - Aroma/Flavor, 15 min boil time
1 oz Cascade Hops 7.1% AA - Aroma/Flavor, 5 min boil time
2 oz Simcoe Hops - Dry hop for 10 days
Yeast - Danstar Dry 97 West Coast Ale, 2 packets

Thoughts?

Thanks!

 

[ong]

That's over 100 IBUs, which in my opinion is a bit much. I'd cut the magnum in half. But I'd also consider doing a couple more flavor/aroma additions, too (4 oz of boil hops isn't all that much for an IPA in my book).

 

[Yooper]

Remember that if you're doing a 3.75 gallon boil, you'll end up with 2.5 gallons of wort.

Since you'd have to top off with 2.5 gallons of water to make a 5 gallon batch, you'd be reducing your IBUs in half right there. If you top off with 3 gallons to get to 5.5 gallons, you'd be cutting your IBUs in less than half, even if your recipe had 100 IBUs possible.

In other words, 2.5 gallons of 100 IBU wort, plus 2.5 gallons of 0 IBU water = 50 IBUs at the absolute max. It won't be too bitter, not at all. That's just about the only disadvantage to partial boils, topping off with water and diluting the IBUs in an IPA.

 

[ddicker60]

move the 30min to 15 and add more at flameout/dryhop

 

[ong]

Yeah, but the same amount of hops will produce more IBUs in 2.5 gallons than in 5 gallons. I know utilization won't be as good in a denser wort, but surely not cut in half? I always figured it closer to 20% lower.

 

[BUCKNUTS]

Yeah, but the same amount of hops will produce more IBUs in 2.5 gallons than in 5 gallons. I know utilization won't be as good in a denser wort, but surely not cut in half? I always figured it closer to 20% lower.

You're thinking is wrong look at what Yooper said again it's 100% correct and if you think about it's really logical.


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[blizzard]

move the 30min to 15 and add more at flameout/dryhop

+1

 

[Yooper]

Yeah, but the same amount of hops will produce more IBUs in 2.5 gallons than in 5 gallons. I know utilization won't be as good in a denser wort, but surely not cut in half? I always figured it closer to 20% lower.

Think about it. Say you have a 80 IBU wort of 2.5 gallons at the end of the boil. Then you add 2.5 gallons of water- with 0 IBUs. That means that you then have 5 gallons of 40 IBU wort. it's very simple math.

I don't know where 20% reduction comes from, unless you're only topping up with 20% water- then you'd have 20% less IBUs of course.

Water has 0 IBUs. You can't make them "grow". You either do have them in the wort, or you don't. Since the maximum you can ever have in solution due to the limits of isomeriation is about 100 IBUs in the best case scenario (and not generally able to occur), an IBU greater than 50 IBUs in a 50% partial boil is just not possible. No matter what.

 

[kgg_033]

Yooper just blew my mind. i was of an opinion supported by ONG.
For ease of the following example, i will cast aside the difference in utilization caused by a denser boil.
i thought (for lack of a better expression) that hop bitterness would be doubled (concentrated) based on half the amount of water, then diluted down when i top off. Similar to Koolaid. If I wanted to make a gallon of Koolaid with 1 cup of mix to yeild 100 KAU (Kool Aid units, LOL), but only had a half gallon container to transport it, i would use 1 cup mix in half gallon of water, get 200 KAU in my syrup mix, then diluted it later adding another half gallon = 1 full gallon of 100 KAU. Preferably Grape.
Are you telling me that half a boil volume is not really concentrating the IBU's to double the amount until i top off? i have alot to learn still.....

Incidentally, the recipe calculator I use is on tastybrew.com, and says i would get 90 IBUs. That being said, i have already found some of their mathematics to be flawed. Any help would be appreciated.

Yooper, props to the avatar icon.
Cheers!

 

[BUCKNUTS]

Yooper just blew my mind. i was of an opinion supported by ONG.

For ease of the following example, i will cast aside the difference in utilization caused by a denser boil.

i thought (for lack of a better expression) that hop bitterness would be doubled (concentrated) based on half the amount of water, then diluted down when i top off. Similar to Koolaid. If I wanted to make a gallon of Koolaid with 1 cup of mix to yeild 100 KAU (Kool Aid units, LOL), but only had a half gallon container to transport it, i would use 1 cup mix in half gallon of water, get 200 KAU in my syrup mix, then diluted it later adding another half gallon = 1 full gallon of 100 KAU. Preferably Grape.

Are you telling me that half a boil volume is not really concentrating the IBU's to double the amount until i top off? i have alot to learn still.....



Incidentally, the recipe calculator I use is on tastybrew.com, and says i would get 90 IBUs. That being said, i have already found some of their mathematics to be flawed. Any help would be appreciated.



Yooper, props to the avatar icon.

Cheers!

In your koolaid analogy you are doing the math correctly 200 kau in 1/2 gallon diluted with another 1/2 gallon of plain water with zero kau would net 1 gallon of 100 kau mix. The same would apply to ibu 1/2 gallon of wort at 200 ibu diluted with another 1/2 gallon if water at 0 ibus = 1 gallon at 100. This is exactly what Yooper explained pretty basic math. Another problem is kooiaid mix isnt theoretical and your recipe calculator is, those numbers arent measured ibus but rather they are a prediction. I suspect your 90 ibu would be much less if actually measured.


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[Yooper]

The reason the "kool aid analogy" doesn't work is the way hops oils are isomerized.

Even if you put, say to be crazy, 10 ounces of bittering hops in wort, there is a limit to the amount of hops oils that can isomerize in the wort regardless of wort density. That maximum is generally about 100 IBUs total. That's even a generous guess, as one of the most hoppy beers around, Pliny the Elder, calculates out to something like 250 IBUs but has been tested at something like 80 IBUs.

It has to do with the solubility of the hops oils, and the ability of the oils to isomerize before the wort is saturated with the hops oils and no further isomerization will occur.

Even though in theory, that could be 100 IBUs or so, generally it's been measured at less than that.

So, even if you could get 100 IBUs into the wort (not likely, but as a "best case scenario), any top off water added to a concentrated wort would necessarily reduce the IBUs by the amount of water added.

With the Kool-aid analogy, using 1 cup of sugar in your gallon of kool-aid (or whatever) will work fine when diluted to 2 gallons as the sugar doesn't need to isomerize- it just simply must dissolve. That is totally unlike hops oils isomerization reaching a maximum.

 

[kgg_033]

Thanks for the explanation, and thanks to all that replied. That is all very good to know.