Fermentation By-products (OG,FG and ABV) [Warning: Math]

Discussion in 'Homebrewing' started by BobbyLager, Feb 27, 2015.

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  1. BobbyLager

    BobbyLager Initiate (0) Feb 11, 2015 New York

    Brewers,

    What would the difference between true ABV, and estimated ABV (using OG and FG), tell me about my beer? Estimated ABV assumes (almost) all fermented fermentables are converted into alcohol and CO2, which is never the case, so the difference should be able to estimate the extent to which byproducts were produced during fermentation in terms of ABV. To this number we can then apply the inverse of the estimation formula to reach an estimate of byproducts in terms of gravity points. See image.

    https://www.dropbox.com/s/3o6ihm4fesqg7mq/ByproductEst.jpeg?dl=0

    Of course, byproducts (esters, fusel alcohols, ketones, various phenolics and fatty acids) vary in density/size, but the above provides an aggregate ESTIMATE of the gravity difference caused by them.

    This topic came up today when I was talking to an executive at a brewery who expressed frustration at the fact that distributors were asking for TMI on the brewery's beers (including OG). I tried to reason as to why they would want to know OG, then I realized that they might be using the information to estimate byproducts influencing flavor/aroma and shelf stability.

    Thoughts?

    Sources: How To Brew
     
  2. pweis909

    pweis909 Grand Pooh-Bah (3,176) Aug 13, 2005 Wisconsin
    Pooh-Bah Society

    Why is it too much information? As a brewer and beer drinker, I find this type of information interesting. It helps me understand the beer. For the average consumer, perhaps not too interesting, but for those in the know, OG + ABV can help me understand how dry a beer is going to seem. I brewed a saison once that went from 1.065 to 1.001. Estimated ABV 8.5%, dry as bone. In contrast, a beer with the same ABV but a higher OG, say a Belgian Quad, might come across as syrupy sweet. You'd have to ask the distributors why they want the info, but that's what it means to me.

    While I know that estimated % ABV assumes a simpler mixture than the reality, the assumption works because those other compounds that vary in density must not really play a significant role (i.e., their concentrations are too low to matter much). I don't know that if we have an accurate ABV and an estimated ABV (or OG), I don't think distributors or consumers would be able to infer useful information about the beer - it still could be any number of compounds responsible for that difference.
     
  3. DrMindbender

    DrMindbender Initiate (0) Jul 13, 2014 South Carolina

    I want the basic beer stats on any bottle I purchase, and honestly could care less how many of the other mentioned compounds are in their beer, because they brewed it that way for a reason, ie for the esters or phenols. It doesn't matter that they may affect the abv, SLIGHTLY. You seem to feel that the distributor is in grad school working on a project or something, because I dont know too many distributors that really give that big of a damn about their products...they would say anything, supported or not, to sell beer. Seems like the stats you are talking about would be way more useful for the brewery than anyone else.
     
    #3 DrMindbender, Feb 27, 2015
    Last edited: Feb 27, 2015
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  4. Naugled

    Naugled Pooh-Bah (1,882) Sep 25, 2007 New York
    Pooh-Bah Society

    I don't think it's TMI. I like when the brewers list the OG. It saves me the trouble of degassing a sample for a FG measurement to estimate the OG myself. I don't do this with every beer, but as a homebrewer I do do it.

    I can't image why a distributor would want to know OG other than for marketing reasons, which the brewery should be ok with. Sure they may be interested in shelf life, but I can't think of any reasonable information they can glean about shelf life by simply knowing the OG.
     
  5. Brew_Betty

    Brew_Betty Initiate (0) Jan 5, 2015 Wisconsin

    I'm more interested in knowing the FG, but not enough to take measurements. Put it on the label.
     
  6. BobbyLager

    BobbyLager Initiate (0) Feb 11, 2015 New York

    Your beer was dry as a bone because it fermented down to 1.001. Simple as that. No OG needed. All that OG is going to tell you is the saturation of the solution at the commencement of fermentation, which is generally irrelevant for determining dryness on its own.

    A significant role in what? How do we know when their concentrations matter? There are compounds that at only a few ppm can have a significant impact on a brew.

    Well, as an example, too much diacetly could have been created during fermentation therefore reducing shelf life. I think both you and the distributor would care about that. If their product spoils in the warehouse, they can't sell it. If it spoils in the fridge, you'll be pissed.

    Right... I think knowing OG would be useful in replicating a beer, and getting a feel for how they make their recipes.

    Like I said, knowing OG could tell them how much 'fuel' the yeast had to begin with, and the extent to which byproducts could be produced, given FG and ABV.

    I love knowing FG. Especially for beers like Ten Fidy.
     
  7. Brew_Betty

    Brew_Betty Initiate (0) Jan 5, 2015 Wisconsin

    What is Ten Fiddy's FG?

    I'm guessing 1.024

    I would mostly like to know the FG for commercial IPA and DIPAs. Way to many of them are too sweet. It's one of the reasons I homebrew.
     
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  8. pweis909

    pweis909 Grand Pooh-Bah (3,176) Aug 13, 2005 Wisconsin
    Pooh-Bah Society

    The premise I assumed from the original post was that the distributor wanted OG in addition to ABV. I assumed the distributor knew nothing about FG, so I used an extreme example to illustrate why ABV is not enough to tell me what I want to know. You are right that OG says nothing about dryness on it's own, but, if you had the ABV and the OG, you can infer something about dryness without the FG.
     
  9. BobbyLager

    BobbyLager Initiate (0) Feb 11, 2015 New York

    It's like 1.030

    It's probably not because of the FG, but rather, because they are using lots of crystal malt (or sometimes lactose). Ten Fidy is pretty dry IMO.
     
  10. BobbyLager

    BobbyLager Initiate (0) Feb 11, 2015 New York

    Yes, infer something... but, the distributor could just plop a hydrometer in the (flat) beer for FG if they wanted.
     
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  11. honkey

    honkey Maven (1,326) Aug 28, 2010 Arizona
    Trader

    My IPA is 1.064 OG and 1.010 FG. No caramel malts and mash temp of 65°C. This will be released in two weeks for the first time.
    My DIPA is 1.074 and 1.008. Has a small amount of crystal 30, low mash temp, and sucrose. This is brewed every 3 months.
     
  12. honkey

    honkey Maven (1,326) Aug 28, 2010 Arizona
    Trader

    I'm not sure why a distributor wants to know OG. My brewery has 4 different distributors and we tell them what we consider the shelf life to be. We also tell them ABV, IBU, food pairings, and descriptions as well as ideal storage conditions. In 2 states (Mississippi and Tennessee) we had to have our beers ABV tested before getting a permit to sell.
     
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  13. FATC1TY

    FATC1TY Pooh-Bah (2,502) Feb 12, 2012 Georgia
    Pooh-Bah


    Yeah, I don't think a distributor needs to know all the info, or should care actually.

    If the brewery says.. it's good for 90 days, and then past it's prime, then that should be good enough. They are there to sell it and thats it. Give them a time frame to sell it and it's on them to supply their accounts.

    Obviously, good notes, and measurement for legal side of labeling and such, but... dsitributor.. I agree.. sell it, thats your job. Very few, if any shops are going to care to know any specific info on a brew.. they just want to sell it. If it taste good, people ask for it, and it can be gotten fresh and moved while fresh.. what else is there to know.
     
  14. icepick

    icepick Initiate (0) Feb 17, 2008 California

    Kind of off topic but You also got breweries saying their iPas and DIPAS are "in code" for 90-120 days. In reality those precious hoppy beers ain't gonna taste the same after a month from bottling/kegging. I wouldn't buy a bottle of a hoppy beer that's over a month month and a half but that's just me
     
  15. BobbyLager

    BobbyLager Initiate (0) Feb 11, 2015 New York

    Good info. Another topic (beer statistic) we covered was IBUs. That number on its own can be misleading. Even IBU to GU ratios can miss the mark in determining how bitter a brew will seem, so as a distributor why do you even need that? I suppose customers will want that information just because they want to feel like bigger hopheads.

    For example: If your IPA and DIPA have the same IBUs, and use the same base malt, the IPA will probably seem more bitter, I'm assuming.

    How do you determine shelf life?
     
  16. FATC1TY

    FATC1TY Pooh-Bah (2,502) Feb 12, 2012 Georgia
    Pooh-Bah


    True, but like you said.. it's just you.

    A brewer might feel, to him, that the beer he designed and made can withstand the torture of sitting for 3 months before he thinks it's different from what he made.

    Doesn't make you, or the brewer wrong.
     
  17. honkey

    honkey Maven (1,326) Aug 28, 2010 Arizona
    Trader

    We tell them IBU's just so they have all the info that they might need. They do not require it from us, but we give it to them anyways. Most likely, they ignore that number and only reference it if they are asked by a retail account. You are right that IBU's and perceived bitterness are two separate things. I know our true alpha acid utilization of additions in our brewhouse, but I ignore the IBU's of late hop additions as I consider them to have about 15% of the perceived bitterness of early additions. My IPA and DIPA's at this point use a lot of hops, but do not seem too bitter since all the hops are added in the last 15 minutes of the boil. The actual IBU's tested are around 95, but our pale ale is tested at 45, with 20 IBU's coming from a 60 minute addition and it seems more bitter than our IPA or DIPA.

    Shelf life for us is determined by how long it takes for our beer to taste oxidized. We have that pegged at 3 months. If we did not have oxygen pick up, it would be based on colloidal stability. As is, we used our tasting panel to help us determine shelf life.
     
  18. PortLargo

    PortLargo Pooh-Bah (1,737) Oct 19, 2012 Florida
    Pooh-Bah Society

    How much will ABV vary from batch to batch? How close is "close enough"?
     
  19. honkey

    honkey Maven (1,326) Aug 28, 2010 Arizona
    Trader

    Legally, .2%. We are usually withing .1
     
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  20. pweis909

    pweis909 Grand Pooh-Bah (3,176) Aug 13, 2005 Wisconsin
    Pooh-Bah Society

    Sure anyone with a hydrometer could waste some beer to get some easily obtained lab result that the brewer already measured and could readily supply to distributors and consumers. Makes a ton of sense. The only reason I can think of for the distributor to want this type of information is so that it is ultimately available to consumers who want this type of information. Consumers may want it to infer something about the beer, like I tried to explain earlier. Or maybe they just yearn for data so they can rattle it off at the bar to impress their friends.
     
    #20 pweis909, Feb 28, 2015
    Last edited: Feb 28, 2015
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