Hop utilisation.

Can we discuss the following chart.




Does any on have any information to show this is wrong or correct?

According to this chart optimal additions are at 7.5, 20 and 60 minutes.
What do yo think about an addition at 30 minutes to get the best combinaton of flavour and bitterness or would you be better splitting the 30 minute between the 60 and 20?
I thought any boiling of hops drove off aroma so have always added aroma hops at flame out.

Thoughts?

I too have pondered this same chart. It looks reasonable though. I have dealt with tons of scientific data in my life and it seems fair enough, but without a corresponding chart to confirm I am not sure. I will say though, that it very much follows our well accepted trend of the 60/15/5. I am sure one could tweak times very much to gain an advantage.

Where I could see a potential gray area is can we safely assume that the increasing intensity of the flavor (for instance) profile is the same on the down side of the curve. Quite often things that are being destroyed in increasing amounts are not the same as things being added in increasing amounts. A good example of what I am getting at with this is when you are cooking and add say I dunno, fresh Garlic. If you add it to a sauce just before flame out you get a high intensity of the Garlic flavor. Now if you keep cooking it will peak and then the flavor diminish. There are some aspects that you had before flame out (the raw pungency) that are not there if you go longer, but yet the presence of the garlic flavor is still there. I would imagine you get a similar effect with hops.

What's the source for the chart?

I typically only use 1 bittering hop and 1 flavor/aroma hop so my additions are typically at 60, 30/20/15 (depending on style), and 5 min.

I think I would go as far as to it is very qualitative, not based on any real data and should only be used as a guide to communicate the general ideas. I could be wrong.

Beerrific said:

I think I would go as far as to it is very qualitative, not based on any real data and should only be used as a guide to communicate the general ideas. I could be wrong.

Click to expand...

I agree. The "perfect" shape of the curves makes it look made-up, rather than being based on any actual data. The chart would have you believe that throwing hops in at flameout would produce practically no aroma, which does not seem right. It looks like a quick-and-dirty chart for demonstration/illustration purposes only, rather than one to be used as a real reference.

I have the feeling that if they constructed the chart from some type of 'measured' values, that they had a very minimal set of points, the perfect look in that case would be from interpolation, and they did it piece-wise. I highly doubt though they measured anything though.

The results however, are probably fair however they did get them in that the trends make sense. The biggest problem I have is the narrow mirror like rise and fall of the first two. The bitterness looks much more 'normal' to what you see in life. It is possible that they constructed the curves based on known utilization/destruction of some of the compounds/oils/etc present in the hops. That would certainly give the seemingly perfect effect as well, although it is highly unlikely that if someone having gone to that extend wouldn't simply leave the set of fits around for others to follow.

Homebrewers tend to be affixed on Utilization numbers alone. It would be nice to see graphs corresponding to floral and ester characteristics of the hops. To really do this though, we'd basically need the rates of every single dominant oil/etc as a function of time. You could probably group each thing as a family and make some form of rough estimate of what 'flavor' or 'aroma' levels are as a function of time.

I have a serious problem with the bittering curve. The curves I've seen from OSU's hop testing show a smooth curve with an asymptote around 90 minutes. The simple fact that the OP's chart shows nearly 15% utilization at 0 minutes, makes it obviously wrong. Utilization is very low at 0, about 1/3 max. at 10 minutes, 2/3 max. at 25 minutes and within 1-2% of max. by 90 minutes.



Sorry about the image quality, I'll try to find a better one.

The flavor/aroma curves are a tougher call. There are dozens of 'oils', the lightest & most volatile we call aroma, heavier ones, flavor. What research I've found is so abstract that I can't map it back to beer.

david_42 said:

I have a serious problem with the bittering curve. The curves I've seen from OSU's hop testing show a smooth curve with an asymptote around 90 minutes. The simple fact that the OP's chart shows nearly 15% utilization at 0 minutes, makes it obviously wrong. Utilization is very low at 0, about 1/3 max. at 10 minutes, 2/3 max. at 25 minutes and within 1-2% of max. by 90 minutes.

Sorry about the image quality, I'll try to find a better one.

The flavor/aroma curves are a tougher call. There are dozens of 'oils', the lightest & most volatile we call aroma, heavier ones, flavor. What research I've found is so abstract that I can't map it back to beer.

Click to expand...

It almost looks (like I was hinting at before) was that in the OP they took the exponential portion (which is what one sees normally in many real life reactions) and then pieced in a linear fit earlier in time. Good call on the initial point as well. At time zero all of them should really be zero, which again makes me suspect that they somehow backfit something.

The more I look at this the more it shouts 'Franken-graph'. Coupled with your own research, and the fact that we haven't seen more of these types of graphs surface for the general public makes it highly suspect that the problem is complex enough that few have chosen to undertake it.

I'm not ready to discount the aroma curve yet. However, I'm "suspicious" of the bittering curve though. Certainly boiling hops drives off aromas, so it that regard, flameout additions make the most sense. However are the aromas present in the final product exactly the same ones well smell in the wort? I guess what I'm saying is that with the 5 minutes of boiling we certainly will de driving off some aromas, but maybe NEW compounds are created in that 5 minutes of heating that will be realized as aromas in the finished product. Also I believe we are all aware of how fleeting the aromas from dry hopping can be. 6 month down the road, dry hopped beers can loose a lot of the aroma punch - not that the beer will last that long. Maybe the five minutes of boiling leads to a more stable, longer-lived aroma? This is an answer I'd really like to know!

Now as to my "suspicions" of the bittering curve. My suspiciousness is more that I think the bittering curve is a bit too simplistic and a bit misleading. (It is however the best we've got right now). We are told it takes 30+ minutes of boiling to get good hop isomerization. My assumption (fairly certain though) is that the isomerization reaction is not as simple as A+B = C. I'm sure that does take place, but then C is also free to combine with other compounds produced in the boil - like a rolling snowball. The net result being that a greater number of DIFFERENT hop products (not just more) will be produced in a 60 min. boil compared to a 5 min boil. It is not simply a linear extraction where the longer you boil the more extraction you get. This is partly true to be sure, but there are other reactions going once the oils have been extracted, and these take time. I find it hard to believe that the bittering component of a 5 min addition will simply taste like ~1/10th of that from a 60 min boil. Unless our tongues are unable to differentiate between the compounds - which I doubt.

With my brews I keep separate track of how many IBUs I use for each of the 3 std. additions, and am not so concered about the total # of IBU's becuase I think it is a bit of adding apple and oranges, and cherries. I think high IBU beers are a bit of marketing. Microbrews like to tout their manly IBU levels. I've had commerical pilsners at 40 IBUs that taste a LOT more bitter than some Micros that claim 100+ IBUs. Hopbursting is the difference. Punch in the numbers from a slam of high Alpha Acid hops added at 5 min, do the calculations and presto, out-of-this world IBUs. Just because the equation works well for bittering and flavor additions, that doesn't mean it work well for aroma additions. As I said earlier though, it is the best tool we have right now. I would really like to see a computer program just for aroma hop additions that takes into account the different oil profiles of the various hops, not just the alpha acid conent. By blindly relying on alpha acid content, this would tell you that to substitute Saaz hops for a 5 minute addition of Magnum hops you would have to add up to 5 times as much Saaz hops. Maybe for bittering this "might" be true, but certainly not for aroma!!!!!