IBUs from hop steeping additions.

[p_p]

Hi everybody,
I wonder what is the latest trend for calculating IBU contributions from flame-out additions.

In some cases, I am adding hops after flame-out at different temperatures (80C/176F, 70C/158F) and standing for up to 40min, in other cases I am adding right at flame-out and doing a short steep, 10-20 min. before cooling. It is difficult to know how much bitterness is being added in each case...

I found a thread from 2011, in which it is said that below 180F there is no isomerization, but does not seem to be my experience.
Does anyone know how the leading brewing software calculate this? I am brewing using a spreadsheet and I'd like to add this as a feature rather than just eye-balling the values I type in.

Thanks,
pp

 

[plankbr]

Here's a good article relating to this.

This was also extracted from BA:
Per Matt B. of Firestone Walker:

"Adding hops late in the whirlpool results in lower isomerization of alpha acids and good uptake of hop oils and flavor components (especially with pellet hops). The fact that there is some isomerization (about 15% in whirlpool versus 35% in the kettle) of alpha acid means that not only hop aroma and hop flavor can be achieved, but also some bittering."

15/35 = 43% relative utilization - I like to use 50% as my number... eg if you added to hops at the beginning of a 30 minute whirlpool without cooling, calculate IBUs contributed to a 30 minute boil and half that number.

 

[dmtaylor]

Hi everybody,
I wonder what is the latest trend for calculating IBU contributions from flame-out additions.

In some cases, I am adding hops after flame-out at different temperatures (80C/176F, 70C/158F) and standing for up to 40min, in other cases I am adding right at flame-out and doing a short steep, 10-20 min. before cooling. It is difficult to know how much bitterness is being added in each case...

Personally, I find a good swag to be to treat the whirlpool ("steeped") additions as being boiled for half the time as the steep, regardless of temperature as long as it's still "warm" (maybe >110 F). So if allowing 40 minutes before pulling the hops out and before reaching a chilly temperature, then for IBU calculation purposes, treat the hops as if they had been boiled for 20 minutes.

If chilling is going on at the same time and you hit 70 F within say 15 minutes, then obviously you won't get as many IBUs, maybe only 5 minutes worth.

As a swag, it truly works. Use a bit of sense and you'll be in the right ballpark.

 

[p_p]

Personally, I find a good swag to be to treat the whirlpool ("steeped") additions as being boiled for half the time as the steep, regardless of temperature as long as it's still "warm" (maybe >110 F). So if allowing 40 minutes before pulling the hops out and before reaching a chilly temperature, then for IBU calculation purposes, treat the hops as if they had been boiled for 20 minutes.

If chilling is going on at the same time and you hit 70 F within say 15 minutes, then obviously you won't get as many IBUs, maybe only 5 minutes worth.

As a swag, it truly works. Use a bit of sense and you'll be in the right ballpark.

Thanks for your reply.
You are not the only brewer that claims stepped additions can be treated as boil for half the stepping time.

But if I use these numbers, beers I brewed with lots steep additions calculate over 80 IBUs where in reality they felt more like 50-60 IBUs.
Looking through my brew notes, the perceived IBUs in all my beers are, to certain extent, below the calculated numbers.

I understand perception depends on the beer .. OG, type of hops, yeast used pitching rate, process in general.

So do you think it would be fear to calculate Boil IBUs using, lets say, Palmer's method and steep additions as 1/2 time and then apply an overall factor for that beer based on the perceived IBUs?

Thanks

 

[dmtaylor]

Thanks for your reply.
if I use these numbers, beers I brewed with lots steep additions calculate over 80 IBUs where in reality they felt more like 50-60 IBUs.
Looking through my brew notes, the perceived IBUs in all my beers are, to certain extent, below the calculated numbers.

It also depends on what formula your software is using. Some use the Rager formula, which notoriously over-estimates the IBUs especially in very hoppy beers. Tinseth formula is most accurate. Ensure you are using Tinseth.

So do you think it would be fear to calculate Boil IBUs using, lets say, Palmer's method and steep additions as 1/2 time and then apply an overall factor for that beer based on the perceived IBUs?

Honestly I'm not very familiar with the Palmer method. I'd still wager that you might be using the Rager formula, which I know is way off. Tinseth isn't perfect either, but not too far off, maybe slightly high by 5% or something, when compared with some various independent lab results. YMMV.