Mathematical model for hop flavor and aroma? - Home Brew Forums
Home Brew Forums > Home Brewing Beer > Brew Science > Mathematical model for hop flavor and aroma?

Reply
 
Thread Tools
Old 05-01-2012, 02:49 AM   #1
alestateyall
Recipes 
 
Jun 2011
Posts: 735
Liked 89 Times on 58 Posts



Is there a mathematical model for hop aroma and flavor in beer?

I think I understand the basic relationships:

1. More hops equals more flavor and aroma
2. Later hop additions increase hop aroma and flavor
3. Dry hops increases hop aroma

I currently have 2 beers on tap:

Beer 1: OG 1.044, grain bill 2-row & caramel malts (9%), 1oz citra @ 15 min, 0.5oz citra @ 0 min, 0.5 oz citra dry hop 7 days

Beer 2: OG 1.058, grain bill 2-row, wheat (8%), Munich (8%), 0.5 oz Simcoe @ 30 min, 1 oz Simcoe @ 15 min, 1 oz Simcoe 5 min, 0.5 oz Simcoe @ 0 min, 1 oz Simcoe dry hop 7 days

Beer 1 has great hop aroma and flavor

Beer 2 has OK hop flavor and not much aroma

I would expect more aroma and more hop flavor from beer 2 but that is the opposite of what I got.

Maybe this is expected with Simcoe vs. Citra. Alternatively, maybe the bigger gravity mutes the hop flavor and aroma profile.

My question is are there numbers or equations that would help me predict this?

Thanks!



 
Reply With Quote
Old 05-01-2012, 05:40 AM   #2
Andrew5329
Recipes 
 
Nov 2011
Salem, Massachusetts
Posts: 170
Liked 3 Times on 3 Posts


doublepost sry!



Reason: Doublepost

 
Reply With Quote
Old 05-01-2012, 05:41 AM   #3
Andrew5329
Recipes 
 
Nov 2011
Salem, Massachusetts
Posts: 170
Liked 3 Times on 3 Posts


A large factor is the size of your boil. I'd bet money your first boil had a larger volume than your second. You can throw in all the hops you want but a given volume of water will only dissolve AA so readily.

I'd recommend http://www.beersmith.com/ it's a paid program but there's a 21 day free trial. It has all those mathematical equations you requested built into it, plus a database of values for most of the commercial hops/grains available as well as a rough price gauge for when your planning a recipe.

Also, later hops = aroma,
early hops = flavor because the boil releases the Alpha Acids that give you the flavor.

 
Reply With Quote
Old 05-01-2012, 11:48 AM   #4
alestateyall
Recipes 
 
Jun 2011
Posts: 735
Liked 89 Times on 58 Posts


The boils for the 2 beers were both full boils. Both were about 7 gallons before boiling.

Are you saying Beersmith has equations for hop aroma and flavor? Lots of programs have an equation for hop utilization (Tinseth or Rager) which is used to predict bitterness.

Thanks.

 
Reply With Quote
Old 05-01-2012, 11:52 AM   #5
ajdelange
HBT_LIFETIMESUPPORTER.png
Recipes 
 
Aug 2010
McLean/Ogden, Virginia/Quebec
Posts: 8,919
Liked 1365 Times on 1040 Posts


Apparently you are aware that there are several models for bitterness as a function of hop amount, hop alpha acid content, wort strength and boil time. Search Rager, Tinseth... with bitterness. These work, but not that well because the perception of bitterness is tied to the amounts of isomerized hop acids in the beer and it is possible to roughly estimate the amount of those from the parameters listed above. These models do not consider wort pH, however, and that also has an effect.

Bitterness is pretty much bitterness (though there is fine bitterness and coarse bitterness) but when it comes to flavor and aroma there are many more dimensions: fruity (several fruits), citrusy, spicy, floral, piney, earthy, licorice like... One could try multiple experiments where drinkers perceived flavors and aromas were tied to certain compounds (licorice to ethyl hexanoate, for example), many hops cultivars anaylyzed for their content of these compounds and all that data stirred up into a big principal components analysis (PCA) but the task would be daunting and not something that would be of practical use to brewers. I don't doubt that some of the things I'm suggesting here have already been done and can be found buried in the literature.

Practically speaking, control of aromas and flavors is done through the brewers knowledge of which hops cultivars present what flavors and how to handle these hops in order to avoid volatilizing the essential oils that are responsible for the aromas and flavors the oils deliver. Another approach is to obtain (either by purchase or extraction) these essential oils and then dose them into the finished beer to taste.

 
Reply With Quote
Old 05-01-2012, 01:56 PM   #6
pjj2ba
Look under the recliner
HBT_LIFETIMESUPPORTER.png
 
pjj2ba's Avatar
Recipes 
 
Jul 2006
State College, Pennsylvania
Posts: 3,382
Liked 205 Times on 167 Posts


I've not seen a formula for aroma and flavor, just for bitterness. It certainly would be nice.

I've toyed with the idea of making a rough estimate of the oil content in my house IPA recipe and then trying a different combination of hops that gives me the same oil profile. The problem is most of the data on hop oils gives a range of content so it is not that accurate. For this to really work, you would need more accurate oil values, akin to what we get for AA percentages.
__________________
On Tap: Doppelbock O'fest, Pale Ale, cider
Kegged and Aging/Lagering: CAP, Ger. Pils, OKZ (std Amer. lager), CZ Pils, Amer. Wheat, Rye IPA, Saison
Secondary:
Primary: Ger Pils, CAP
Brewing soon: Pale lager, Amer. wheat
Recently kicked : (
Pilsner Urquell Master Homebrewer
(1st NYC 2011, 2nd NYC 2012)
P U crowns winners in its inaugural master HB competition

 
Reply With Quote
Old 05-01-2012, 02:51 PM   #7
dbhokie
Recipes 
 
Mar 2012
Lynchburg, Virginia
Posts: 407
Liked 8 Times on 8 Posts


Everything with Hops is a guess, there are a few standard equations out there that some people have come up with. I tend to use Tinseth's model, Rager and some other's are out there. Here are the equations for IBUS:

IBUs=AAU*Utilization*74.9/Volume
Utilization = BTF*Bigness Factor
Bigness Factor (SG of boil determination) = (1.65*(.000125^(PreBoilSG-1))
BTF (length of boil determination) = (1-(2.71828^(-.04*BoilTimeMinutes))/4.15(this can be adjusted to mimic your kettle efficiency and dial in the equation (the 4.15 number))
AAU (Alpha Acid Units) = Weight(oz)*(AA(alpha acid percentage)*100) eg: 2 oz hops with 4.5 AA (2*(.045*100))= 9 (tettnang)

The 4.15 number as mentioned above in the BTF Factor, can be adjusted to adjust for your Kettle's efficiency. Every boil has a different gravity, different chemical interactions, different boil, etc..but this will get you in the ball park. A lot of people use Rager's equations as well, but those are the ones I use in my spreadsheet.
__________________
On Deck
Abbey Ale #2
Rye Imperial Pale Ale
Primary
20 Gallons of Apple Cider
Secondary
Bourbon Vanilla Imperial Porter
Conditioning (Bottle)
---So Sad

 
Reply With Quote
Old 05-01-2012, 02:51 PM   #8
alestateyall
Recipes 
 
Jun 2011
Posts: 735
Liked 89 Times on 58 Posts


Do you know which oils contribute to aroma and flavor? In my case on the Simcoe versus Citra comparison there is data like this available:

http://www.hopunion.com/17_HopVarieties.cfm?p3=open

The oil contents are generalized but that would be a start.

Thanks.

 
Reply With Quote
Old 05-01-2012, 02:54 PM   #9
alestateyall
Recipes 
 
Jun 2011
Posts: 735
Liked 89 Times on 58 Posts


Quote:
Originally Posted by dbhokie View Post
Everything with Hops is a guess, there are a few standard equations out there that some people have come up with. I tend to use Tinseth's model, Rager and some other's are out there. Here are the equations for IBUS:

IBUs=AAU*Utilization*74.9/Volume
Utilization = BTF*Bigness Factor
Bigness Factor (SG of boil determination) = (1.65*(.000125^(PreBoilSG-1))
BTF (length of boil determination) = (1-(2.71828^(-.04*BoilTimeMinutes))/4.15(this can be adjusted to mimic your kettle efficiency and dial in the equation (the 4.15 number))
AAU (Alpha Acid Units) = Weight(oz)*(AA(alpha acid percentage)*100) eg: 2 oz hops with 4.5 AA (2*(.045*100))= 9 (tettnang)
Thanks, but, I am not asking about bitterness. I am asking about a mathematical model for aroma and flavor (not bitterness flavor, maybe best put has flavor from hop oils).

 
Reply With Quote
Old 05-01-2012, 03:05 PM   #10
dbhokie
Recipes 
 
Mar 2012
Lynchburg, Virginia
Posts: 407
Liked 8 Times on 8 Posts


No, but I would think if you came up with a subjective flavor profile (the flavors they convey may be perceived different to different people, From my generic understanding the isomerization of the Beta Acids are what convey your "aroma's" and flavor. They do not isomerize during an extended boil, which is why they tend to convey bitterness then. There are a few major types of these oils, and if you could establish a spreadsheet imparting a table with the different base oils, and a cross-reference to your associated taste, you could come up with some equations for them I suppose.

EDIT: Although to ensure accuracy of your calculations with your setup, you would need some lab equipment to measure the oil levels, A great cook though, doesn't measure chemical flavor profiles with lab equipment at the end, it could be done, I suppose, but it would take more equipment than I have to get it right, that's for sure.


__________________
On Deck
Abbey Ale #2
Rye Imperial Pale Ale
Primary
20 Gallons of Apple Cider
Secondary
Bourbon Vanilla Imperial Porter
Conditioning (Bottle)
---So Sad

 
Reply With Quote
Reply
Thread Tools



Forum Jump