I know to use AAs to calculate IBUs for bittering, but in another thread it was mentioned that the super high-alpha hops have a lot of oils in general and can overpower other hops from a flavor/aroma standpoint. I’d never considered that there might be concentration effects in late additions. When I use combinations of hops for the 15 and 5min adds, its generally just equal amounts.
My question is, do you adjust the amount of each according to AAU, or do you look up total oil content, or do you just use amounts based on taste experience? And do you think certain combinations are good simply because they are similar AAs along with complementary flavors?
I first decide the type and amount of hops I want in my late additions (0 - 20 min) to give me the flavor & aroma that I like & what’s appropriate to style. This doesn’t usually give me the bitterness that I am shooting for so I pick a smooth, high alpha, low cohumulone variety for my 60 min addition and let ProMash tell me how much to hit my IBUs. I don’t pay any attention to oil content, but make my late addition based on experience.
What ipaguy said. With the shorter times and generally lower AAs of your late additions, not a lot of IBUs result. That’s not what you’re going for with those additions anyways. Use your experience, other recipes, etc. to try and get the flavor/aroma profile you’re after. Then use you brewing software and let it tell you how much bittering addition you need to reach your desired IBU.
I hadn’t read or heard of this before, but its an intriguing idea and seems intuitively reasonable. Considering that super-high alpha hops are a relatively recent invention, it would become more critical than when most hops were in the 3-6% range.
Also, it would explain my disatisfaction with my most recent late addition blend for my APA, where it comes across as somewhat one-noted. It included 18% Summit in the blend, the other two were 12% at most. I suppose if the Summit were 1/3 more potent for all oils, then it would only contribute: 18/ (12+12+18 = 42, or 43% of the total flavor/aroma. As opposed to the 33% I thought I was getting.
I think a have a book somewhere that lists oil percentage ranges for different varieties, but can’t find it right now. Unfortunately suppliers don’t list the values by batch like they do for AA%. Even if they did I don’t think it would do you much good; Some of the flavor and aroma compounds in the oil are going to be orders of magnitude more intense per unit weight than others. I think the only way to tweak your late adds is going to be either trial & error, or maybe making hop teas.
Just found my table for ranges or %AA, %BetaAcids, and %oil for 20 varieties. Looks like a pretty loose correlation between %AA and %oil. I’ll run the stat’s to see what the correlation coefficient is, just for fun. I still don’t think it will mean much since I’ll bet oil composition varies a lot variety-to-variety.
Edit: Looks like there is some positive correlation between AA & oil, but correlation coefficient is only 0.656 The scatter plot looks like this:
Doesn’t seem very useful in drawing strong conclusions on aroma & flavor vs. bitterness.
Quality is important of course, and why its worth using blends. But getting a similar amount of the various essential oils would hlpe create a balance, assuming of course that the different oils have similar “strengths”.
Interesting, just looking at the graph it appears there is at least a weak correlation. I suppose it would be better than nothing. Maybe instead of AA it would pay to balance on the basis of oil content.
I think even going by oil content wouldn’t tell you much in trying to compare varieties. They differ too much in the quality of their taste & aroma. Maybe if you knew the %oil in two different batches of the same variety that could give you useful information on how much to use to keep a recipe consistent. It might actually make sense to scale your hop bill in such a way the you scale bittering hops based on %AA while scaling your flavor/aroma hops based on % oil. Of course you would have to perform your own assay on each hop shipment. Probably beyond the means of the average homebrewer. If I was running a micro with a lab I would definitely consider it though.
I too, have wondered about blending late additions of hops with greatly varying AA%. Shooting from the hip, I’ve been scaling my late additions according to AA of the hops, thinking this will bring balance and allow the unique character of each hop to come through.
For example, if I had an ounce of Columbus @14% AA at 10 mins, then I would need to add ~2.5 ounces of Cascades @ 5.6% AA to bring out a distinct Cascade character because it’s AA is 2/3rds less than the Columbus. Although as I type this out, I guess measurable bitterness from the AA and the flavor\aroma characteristics are two different things and probably not related in a linear way.
Anyone doing it this way or have some experiments they’ve tried to see if this is case?
My impression is that if you scale your late additions based on %AA you are going to be getting (on average) a lot more hop oils from your low AA hops. When I put a trend line on my chart of oil vs. AA I found that for a ‘typical’ 5.5% AA hop you get around 1% oils, while for a ‘typical’ 14% AA hop you get around 1.6% oils. In general, oil content seems to increase at a much slower rate than alpha acids. I still think that any mathematical formula is basically going to be something of a WAG, and you are going to have to fine tune by taste.