Converting % of alphas into weights

[Willtwocircles]

I have been sent a recipe that gives hop additions as:

Chinook: about 30% of the alpha, add at start of boil

Chinook: about 20% of alpha, add 10mins before end of boil

Cascade: about 20% of alpha, at the end of boil

Citra: about 30% of the alpha, at the end of boil

How can I convert these percentages into weights (ideally grams) for a 20L batch size?

 

[Yooper]

You'll need to know the total IBUs and then do the percentages of those for the recipe.

 

[Willtwocircles]

You'll need to know the total IBUs and then do the percentages of those for the recipe.

The only other information I have is a 33% utilisation of the alpha from the start of the boil, about 15% 10 mins from end, and about 5% when added at the end of the boil. Is this sufficient?

 

[Willtwocircles]

You'll need to know the total IBUs and then do the percentages of those for the recipe.

target IBU = 45

 

[Blackmuse]

The only other information I have is a 33% utilisation of the alpha from the start of the boil, about 15% 10 mins from end, and about 5% when added at the end of the boil. Is this sufficient?

Can you post the recipe by chance?

The only other information I have is a 33% utilisation of the alpha from the start of the boil, about 15% 10 mins from end, and about 5% when added at the end of the boil. Is this sufficient?

@Yooper
These are pretty low utilization percentages aren't they? (well, the 0min additions at 5% is probably pretty accurate)

 

[Yooper]

I don't think we're actually talking about utilization percentages of the boil- that doesn't make sense. I think they are saying to get those IBUs in those percentages from those boil times- does that make sense?

"Get 33% of the IBUS from the 60 minute addition, etc" is how I read that.

 

[Blackmuse]

I don't think we're actually talking about utilization percentages of the boil- that doesn't make sense. I think they are saying to get those IBUs in those percentages from those boil times- does that make sense?

"Get 33% of the IBUS from the 60 minute addition, etc" is how I read that.

That makes WAY more sense! I thought it was Utilization because in the first post it was stated as 30, 20, 20, 30 - which equals 100...

33, 15, 5 and 5 does not = 100...

See what I mean?

 

[Zambi]

I read it as 30% of 45 ibu for the 1st adfition, 20, 20, 30 for the next
So 13.5 IBU coming from the first addition, then 9, 9, and 13.5 IBU
Check % alpha acid and calculate right amount

 

[Blackmuse]

I read it as 30% of 45 ibu for the 1st adfition, 20, 20, 30 for the next
So 13.5 IBU coming from the first addition, then 9, 9, and 13.5 IBU
Check % alpha acid and calculate right amount

This is how I read it. The additional number given made it sound like utilization percentages based on process (like whirlpool) and possibly age/condition of hops?

Which 5% for whirlpool is probably close...
However, 33% and 15% are not....
​

 

[Blackmuse]

@Willtwocircles
Hopefully this quick video can help explain why we need a bit more information to help you turn those % into numbers. @Yooper @Pricelessbrewing - please feel free to comment and correct anything - especially in regards to whirlpool and the program in general.

 

[Blackmuse]

@Willtwocircles - I have a lot of time on my hands at the moment (if you couldn't tell) and thus, have been doing a lot of reading... I came across something that made me think of your situation... I'll link the article below (it is on the BYO website and I believe it is free to read (I subscribe))... The article was written by Brad Smith and is called "Save Your Hops for Post-Boil". It talks all about hop oils, aroma and flavor additions. His final thoughts on the matter are:

"In conclusion, my best advice is to drop the flavor and finishing hops. Go with a single bittering addition to reach your target IBU level, and then appropriate use of hops in the whirlpool or through dry hopping, depending on which hop oils you are trying to highlight. Also, you might want to consider dry hopping during active fermentation for a unique aromatic note in your next IPA." (Smith, Brad. "Save Your Hops for Post-Boil" https://byo.com/article/save-hops-post-boil/)

How does this relate to you? You may want to consider gaining your 45 IBUs from the 1 Chinook addition at the beginning of the boil and then dry hop the rest or conduct a whirlpool after the boil is done. While this doesn't help you with "weights" - ie HOW MUCH of each... you could start small on the dry hop or whirlpool and adjust to taste on a subsequent batch.... Completely up to you. I just thought I'd share....

Obviously, if you provide more info. we'll still gladly help with your recipe

Happy Reading and/or brewing!