60 min IBU VS 10 MIN IBU?

[bigdaddybrew]

The Brulosopher was comparing two batches of beer. He had the beers analyzed for IBUs. Beersmith using Tinseth predicted about 44 IBU but they analyzed at about 25 IBU. Here is a link to the exbeeriment..
http://brulosophy.com/2016/03/21/kettle-hops-loose-vs-bagged-exbeeriment-results/

I wonder if the difference was a general under calculation by the Tinseth formula or is it possible that late hop additions are not simply smoother as "they" say but actually produce a lower IBU?

I entered some numbers into Beersmith using Tinseth...
5 gallon batch
70% efficiency
10 pounds of 2 row
OG=1.051

Hop schedule #1...3 oz of Centennial hop pellets 10% alpha for 10 min...IBU=46
VS.
Hop schedule #2...1.09 oz of Centennial hop pellets 10% alpha for 60 min plus 1.91 oz at 175f of whirlpool...IBU=46

If they were sent to a lab I wonder how the IBUs would compare?

How do you think the flavor, bitterness and aroma of these beers would compare?

 

[Cardassian]

I think the late addition hopped with 3 oz would have a lot more flavour and aroma.
I think the one hopped earlier would seem more bitter.

 

[bigdaddybrew]

Both have 3 ounces. Both have late hop additions. I agree the beer with the 60 minute addition would probably seem more bitter. I would love to see the IBUs analyzed.I'm not sure about the flavor and aroma difference.

 

[imasickboy]

Tinseth is a more modern method, and is more accurate with the complex hop schedules commonly found today. The formula should not be inaccurate. The hop utilization factor a brewer tells their software to use is what is wrong when the calculated IBU's don't match actual lab tested values, provided all other measurements were exact.. Utilization will change based upon your equipment, and is a changeable value in Beersmith's equipment profile.

As for your proposed experiment, I personally think, (without doing actual research to back it up), that if chilling to a point below whirlpool temperatures was done nearly immediately, your IBU values should come out roughly equal. If chilling takes a while, I would think you will get more IBU's per minute out of hops that are fresh into to wort than the ones that were already in there for a while. A "diminishing returns" type of thing. There is only so many IBU's you can get out of a hop, no matter how long you boil it, so as a result, I would expect the IBU extraction level to decrease the longer it is in the hot wort.

But anyway, those are just my thoughts, and I expect someone will come along and provide actual data to either correct, or support my thoughts.

I'll not even bother to discuss perceived bitterness, because that is unique to the taster.

 

[bigdaddybrew]

So I edited the original post from...add 1.91 oz at 0 min to...add 1.91 oz at 175f of whirlpool to eliminate whirlpool isomerization of the late hop addition. This should theoretically make the IBU calculation even closer.

 

[bigdaddybrew]

Tinseth is a more modern method, and is more accurate with the complex hop schedules commonly found today. The formula should not be inaccurate. The hop utilization factor a brewer tells their software to use is what is wrong when the calculated IBU's don't match actual lab tested values, provided all other measurements were exact.. Utilization will change based upon your equipment, and is a changeable value in Beersmith.....

I trust that the Brulosopher knows how to use Beersmith so this wouldn't explain the significant difference between the calculated IBUs and analyzed IBUs.

 

[imasickboy]

I trust that the Brulosopher knows how to use Beersmith so this wouldn't explain the significant difference between the calculated IBUs and analyzed IBUs.

If he has followed Beersmith's instructions, he hasn't changed that value. It tells you to set the value at 100% for batches under 20 gallons. That's it. No further instruction.

Having said that, without having had your beers tested repeatedly, you have no idea what to actually change that value to. Most people on this site, myself included, cannot say for certain what utilization they are getting.

One thing he doesn't address is the age of the hops. In that particular recipe, the cascades can be 6 months old, in vacuum sealed packages, stored frozen, and can still account for at least 10 IBU difference. I understand that the IBU discrepancy wasn't the point of the experiment, and wasn't addressed, but I find it worth mentioning, because you're blindly trusting that someone knows exactly what they're doing, when it's likely they didn't account for all the variables.

 

[bigdaddybrew]

Iamasickboy your best explanation is that the Brulosopher has his Beersmith settings messed up or used old hops to do his exbeeriment? This doesn't seem to fit his reputation.

I would like to think Mr. Tinseth had tested his formula against actual IBU analysis before releasing it on the brewing world so maybe Brulosopher's inadvertant IBU descrepancy is just an anomaly.

My question remains...I wonder how different the beers produced by the two hop schedules in my original post would be? Theoretically they should be somewhat similar and nearly identical IBUs. I think hop schedule #1 would be smoother with less hop aroma and hop schedule #2 being more bitter with more hop aroma.

Any other guesses or opinions?

 

[hobomoto]

I've also wondered for a while if when people describe hopbursting as giving "smoother" ibus if they are in fact actually just getting less ibus and the calculations just arn't that accurate for the modern technique of hopbursting...