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Can never get OG lower than 1.022

Discussion in 'General Brewing Techniques' started by Tyson, 9/10/19.

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  1. Tyson

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    Posted 9/10/19
    Hey guys need some help. I've done 4 batches of various types of beer lagers,ales, and just recently belgian wit. I can never seem to get lower than 1.022 I'm fermenting only in a primary. I fermented 23L on a heat pad on my first brew. Stopped using that then brought a tub filled it with water sat my fermenter in it like a bath and then used a aquiruim heater to keep temputure constant. I aerate the beer before I pitched the yeast I always pitch yeast at the right temp. Im using extract malts and dextrose mainly and recently wheat extract and malt extract. I sanitize everything thoroughly before fermentation.

    Im really at a loss as what I'm doing wrong.

    Recent batch OG 1.050 FG 1.022 after 2 weeks.
    1.7kg black rock whispering wheat
    Briess Bavarian wheat
    15g coriander seeds
    2tbsp Orange zest
    Mangrove jack m21 belgian wit yeast
    Fermenting was fast but no bubbling in airlock suspect gasket leak pitched yeast at 25c and brewed at 24c.
     
  2. Tyson

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    Posted 9/10/19
    And yes hydrometer is reading fine in water
     
  3. LorriSanga

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    Posted 9/10/19
    Hey Tyson...that would be FG.

    I had this problem in the early days.
    My problem was mash temps wern't accurate. Mash to high by accident leaving behind unfermentables.
    How long are you leaving the yeast to ferment?
     
  4. philrob

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    Posted 9/10/19
    Not surprising if you are using two kits in one brew, that is if I read your post correctly.
    The Black Rock and Briess kits on their own are designed to be used with 1 kg of sugar or equivalent for a single batch.
    Instead, you are using a tin of each\ in a single bacht?

    If I'm correct you'll never get much lower than you did.

    You are using enough malt to make 2 batches.

    Try using half of each and add 1 kg of sugar or dextrose for a single batch..
    You'll find you will end up with a much lower FG, as you would wish.

    Don't worry about the half used tins, they'll keep fine in the fridge until you do your next batch. I use tins for my starters, and they do me for several batches over a period of months, and never a problem.
     
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  5. Tyson

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    Posted 9/10/19
    Hey mate cheers for the reply yeah I'm using a beer kit I purchased from a brwq
    Cheers for reply mate I'm leaving yeast in to ferment for about 2 weeks. Sprinkling it directly on top. Cheers
     
  6. Tyson

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    Posted 9/10/19

    Not sure what happened in my reply before I tried to say I'm using a brewkit I brought from aussiehome brew store no suguar or dex was in the kit so I thought it might of fermented out abit more. Do you think adding 1kg of dex will help get a lower FG. Cheers.
     
  7. philrob

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    Posted 9/10/19
    Sure will. If you use the equivalent of 1 can plus the dextrose, you'll definitely get it lower.
     
  8. MHB

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    Posted 9/10/19
    Couple of things worth thinking about.
    For a start OG is short for Original Gravity, you are actually talking about FG or Final Gravity. Not nitpicking but its good if we all use the same terminology.

    When we measure SG (Specific Gravity) we are just comparing how heavy a given volume of a liquid is when compared to water. An OG of 1.050 means that the your wort weighs 1.050kg/L, if you had 23L of 1.050 wort the total mass would be (23*1.050) = 24.15kg.
    The other way we measure the density of a wort is with the Plato scale. Plato (oP) it says that the wort is the same density as a given %WW Sucrose in Water solution. WW means Weight : Weight, for example if you dissolved 100g of sugar in 900g (mL) of water you would have 100g/kg or 10% or 10oP solution.
    There is a rough conversion between SG and oP it is SG = (4*oP)/1000+1 (not an exact answer but more accurate than we can measure across the 1.000-1.100 range where do our brewing).
    If we look at that 10oP solution we can say that it is also has an SG of 1.040.
    What makes your wort heavier than water can be called Solids, from the above if we take an SG reading we could for example say a 1.040 wort was 10% solids, if we had 23L of 1.040 wort we know there would be (23*1.040*10%) or (23*1.040*0.1)=2.392kg of solids dissolved in the wort.
    In your case you have 23L at 1.050 or 12.5oP. Or (23*1.050*12.5)=3.02kg of solids

    Liquid Malt Extract and kits are very close to 80% solids and 20% water. You have added a 1.7kg kit and 1.5kg of LME for a total of 3.2kg, At 80% solids that 3.2*0.8 = 2.56kg of solids in solution.

    If you compare the 2.56kg you added and the reported 3.02kg required to get 23L at 1.050, it might not surprise you that I don't trust your reported OG, if we cant trust the OG its hard to trust the FG either.
    Its very easy to get measurement errors especially as a starting out brewer. Sorry about the long winded explanation above, but if I just said I don't trust your readings that isn't worth much, showing why at least gives a reason to think about it.

    One mistake a lot of brewers make is to not flush the tap out before taking a sample. When using extract the contents of the tap are a lot heavier than the rest of the wort, well worth taking samples carefully next time.
    This includes the temperature you take your readings at, remember hydrometers are only accurate at a given (usually 20oC) temperature, at any other temperature you need to make corrections.

    The other possibility that occurs to me is that you might be cooking your yeast. If we cant really trust your SG readings its fair to worry about your temperature readings, if you are only a couple of degrees hotter than the 24oC you think you are brewing at, you could easily be cooking your yeast so it isn't finishing.

    Worth having a long hard look at your Volume, Hydrometer and Temperature readings and how you are taking your measurements. Cool your ferment down to around 20oC the yeast will preform better and your beer will taste better.
    Mark

    PS
    Just to be clear, adding Sugar or Dextrose (Sugars) wont lower the gravity, both are 100% fermentable, if you replace some or all of your LME that is about 65% fermentable with sugar, that is 100% fermentable from the same OG you will get a lower FG.
    Doesn't apply to Lactose that is 0% fermentable clearly that will add the same amount to your FG as it contributes to your OG. Maltodextrin that might be 35% fermentable...
    Just remember that its the bits that don't ferment that give beer a lot of its body, head and flavour.
    M
     
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  9. Tyson

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    Posted 13/10/19
    My og was 1.050 21L. Really appreciate your time to write out such a detailed reply it's going to help me out. Cheers mate
     
  10. Journeyman

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    Posted 25/10/19
    That is a great post for a newbie like me. Thanks
    1 question though, WHY is it important to get the FG down low? or perhaps, what is it that is changing in the FV that is reducing the weight of the brew? e.g. is a difference in SG from (say) 1.040 to 1.005 the same as from 1.050 to 1015 or is there an ideal FG to achieve for all brews?
    I hope that's clear... :D
     
  11. MHB

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    Posted 25/10/19
    What is changing is the amount of fermented or fermentable sugars(mostly), you are right there is no "ideal" FG, what there can easily be is too much unfermented sugars which will make the beer too sweet.
    When we make a wort, in the mashing process we make a range of insoluble grain constituents soluble. Primarily starch is converted into sugars, but there is a significant amount of protein and dextrines, this is a pretty fair representation
    upload_2019-10-26_6-40-21.png
    If we mess up the mash, we can make a wort with less fermentable sugars and more unfermentable content (mostly dextrines).
    Or even the reverse, ending up with beer that has little flavour, being thin and dry.
    Part of the art (and science) of brewing is to make a beer that we want to drink, it will need a alcohol, protein, sugars balanced with a given amount of bitterness and hop flavours, add in yeast flavours too.

    Clearly the higher the OG the higher the FG, just from the unfermentable fraction of the wort. One of the things we look at as part of a beer design is called "Apparent Attenuation", basically its what we see on the hydrometer as a percentage, or Change/OG*100 from above 1.040-1.005 is a change of (40-5), 35 points, %AA would be 35/40*100=87.5%, or in the second example the same change of 35 points 50-15/50=70% would mean a much sweeter beer compared to a fairly dry beer in the first. Both would have the same alcohol content (Change /7.5=ABV) 35/7.5 = 4.666%.

    Around 75% Apparent is a pretty common result when making Pale Ales
    To answer directly the why, so the beer tastes good!
    Mark
     
  12. TheSumOfAllBeers

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    Posted 25/10/19
    Stupid question time:

    Is the hydrometer touching the bottom of the sample glass when you take a reading?

    If so, get a taller sample glass that lets the hydrometer freely float
     
  13. Journeyman

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    Posted 26/10/19
    Thank you for amazing info - you may want to start running brewing courses professionally. (if you aren't already) TAFE pays pretty well. :D
     
  14. Journeyman

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    Posted 26/10/19
    Hopefully you are familiar with IanH's spreadsheet. In the Hops section, adding in hops choices puts a value in a section labelled %AA - with low values. e.g. Kent G gives 4.9 or Amarillo gives 8.9.
    It doesn't seem this is the ABV reading so is it the AA change in points caused by adding the Hops?
     
  15. Tyson

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    Posted 28/10/19
    Yeah I have a test tube i use.
     
  16. MHB

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    Posted 28/10/19
    I don't use Ian's spreadsheet, but have looked at it.
    Calculating the bitterness of a beer is problematic, often far from an exact science.
    Bitterness is usually defined in IBU's (International Bittering Units) or mg/L (milligrams/L) of isomerised Alpha Acids in the finished beer. That's a fairly modern definition but if we work with it we will all be on the same page.
    Where it starts to get complicated is most people are calculating the end of boil bitterness. Forgetting that during the ferment about 1/3 of the dissolved Iso-Alpha gets lost, it sticks to the fermenter and the yeast, gets blown off in foam... and that 1/3rd can vary by +/-15% (roughly) depending on pitch rate, temperature, dry hops...
    We might have calculated that we will have 45IBU (mg/L) but really we are calculating that we will have 45IBU +/-15% or 38.25 to 51.75IBU (probably).

    To calculate the amount of Iso-Alpha we need to know how much Alpha Acid (pretty much insoluble in wort) we are adding. Hops all have different amounts of AA, this can vary from ~2% to nearly 20% by weight. Clearly the same amount of a 5% AA hop will give you less AA than the same weight of 15% AA.
    Traditional hops like Goldings tend to have lower bitterness (AA) than some of the more modern cultivars, but they tend to have more other flavours (taste and aroma components).
    The mg of Alpha Acid available can be calculated by mass*AA, if we used 25g of EKG with 4.9%AA. we would be adding
    25*(4.9/100) = 1.225g or 1,225mg of AA.
    The same addition of say Amarillo at 8.9% gives 2,225mg
    Naturally this will vary from year to year, as it will with the age of the hops, as they get older they loose AA, depending on how they are stored up to ~50%/year in Cascade stored at 20oC (much less if air and light are excluded and its stored cold, lower loss rate in pellets than flowers).

    Only 20-40% of the AA added to the boil will get isomerised and survive to get sent to the fermenter, this amount is referred to as Utilisation.
    Utilisation is the product of a bunch of factors mainly, Length of the boil, Vigor of the boil, pH, Wort gravity, Mass of AA added, amount of protein in the wort...

    Put it all together and we get a simple equation Predicted IBU's = (mg of AA added * Utilisation)/L
    Remembering of course, that its not really an equation, more an educated guess. Big breweries use experience to tell what sort of utilisation they will get with well known ingredients on the same equipment with lots of practice. They still measure IBU's and blend beers or adjust with prepared pre-isomerised AA, not something we can do at home.
    Worth noting that there is a limit on the solubility of Iso-AA its about 103 IBU at 20oC (less colder), not more than 90 IBU in beer that has-been chilled, no-matter how much hops you add, how long you boil...

    When you buy hops it should come with the AA% value, you should enter this value rather than rely on one that is only a typical value. Never forget that you aren't really getting an exact answer, more of a guidance value.
    I call it a Goldilocks answer, aim for just right.

    Sorry to rabbit on, sometimes a simple answer to a question can be very misleading, especially when its a simple answer to a very complex question.

    Worth reading: - The HBD Palexperiment Results Lab Analysis, Part I
    Mark
     
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  17. Journeyman

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    Posted 29/10/19
    That's not a rabbit, that's full-fledged mink of an answer.

    Thanks very much - that info is excellent in understand WTF is happening in making beer.
     
  18. huey

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    Posted 30/10/19
    Thanks a lot for the insights, Mark! I've had and still have similar issues and will have to try a slightly lower mash temp next time.
     

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