Understanding Hop Bitterness

[Rod]

I use Brewmate as my recipe generator

I make 2 similar Golden Ale recipes

one full strength

the other light

The full strength
Fermentables
2.4 Kg dry malt extract
.75 Kg liquid wheat extract
.15 kg Vienna steeped @ 66C for 60 minutes

Hop bill
9g Amariilo @ 60 minutes
12g Super Alpha @ 60 minutes
18g Amariilo @ 20 minutes
23g Amariilo @ 5 minutes

The IBU is calculated @ 38.3

The low Alcohol
Fermentables
1.5 Kg dry malt extract
.47 Kg liquid wheat extract
.1 kg Vienna steeped @ 66C for 60 minutes
Hop bill
9g Amariilo @ 60 minutes
12g Super Alpha @ 60 minutes
18g Amariilo @ 20 minutes
23g Amariilo @ 5 minutes

The IBU is calculated @ 41.4

The boils are identical as you can see , but the bitterness is 8% higher for the low alcohol

the only difference is the fermentables

the hop bill is the same @ 62 grams

3.3 kg for the full strength

2..07 kg for the low alcohol

as the man once said , why is this so

 

[Eon77]

I would say its because the lower gravity wort equals better hop utilization.

 

[damoninja]

What are your predicted original and final gravities? And are your batch sizes the same?

It may be calculating IBU in relation to the amount of malt that counts toward OG.


Sure the formulas are either in the doco on the web or in the help somewhere?

 

[manticle]

There is an inverse correlation between gravity and hop utilisation. Higher the gravity, lower the utilisation.

It's not the actual gravity that causes it - might be solids from memory (which increase as wort/malt increases) but the utilisation calculations in software are based on empirical observations regarding gravity and hop utilisation.

Also Vienna is a base malt and should be mashed (although your 66 for 60 is doing that but worth pointing out for other readers)

 

[DJ_L3ThAL]

Why is it recommended to boil hops in wort over just water for those doing partials and kits n bits?

If it's a true inverse relationship wouldn't that indicate boiling the hops in just water would ensure maximum hop utilisation which you could then add into a higher gravity brew (taking into account the dilution brought by the hop water)?

Obviously one boil vessel for full batch all grain is the reason hops are boiled in the wort as it would be uneconomical to have two boil vessels, one for hops/water and one for wort.

 

[GalBrew]

Not that I have ever done it, but I was under the impression that boiling hops in water will result in an unfavourable flavour profile (harsh) when compared to boiling in wort?

 

[Rod]

What are your predicted original and final gravities? And are your batch sizes the same?

It may be calculating IBU in relation to the amount of malt that counts toward OG.


Sure the formulas are either in the doco on the web or in the help somewhere?

for the full strength

OG was estimated to be 1.047

FG was estimated to be 1012

for the low alcohol

OG was estimated to be 1.029

FG was estimated to be 1.007

both my brews were with in .0002

The main reason for my question is that the full strength makes a fine brew and I wanted to make a light to match it

I thought the light was a bit more bitter so went back to see the numbers

I think i will make my low alcohol batch with 10g of super Alpha will match the full strength with a 38.4 IBU

 

[ianh]

If you have the same IBU for the lower OG brew then the bitterness will increase. Thus you need to decrease the IBUs to obtain the same balance.

 

[Edak]

Absolutely, the ratio should be that of OG/bitterness. 47/38.3 = 1.227 thus your light should have IBU of 23.6 to have the same balance.

 

[Rod]

If you have the same IBU for the lower OG brew then the bitterness will increase. Thus you need to decrease the IBUs to obtain the same balance.

Absolutely, the ratio should be that of OG/bitterness. 47/38.3 = 1.227 thus your light should have IBU of 23.6 to have the same balance.

great , exactly what I wanted to find out

just changed the recipe

need to leave the super Alpha out

and IBU will be 23.4

thanks to all

sometimes what starts out as maybe a silly question yields good results

 

[ianh]

If you Google beer balance you will get more info. One Link There is also a chart.

The chart and beer balance are calculated in my spreadsheet a sticky in the forum.

cheers

Ian

 

[Edak]

I like the chart but it doesn't show iipa!