100% Brettanomyces Brewing

Discussion in 'Grain, Hops, Yeast & Water' started by SG Brewing, May 24, 2019.

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  1. May 24, 2019 #1

    SG Brewing

    SG Brewing

    SG Brewing

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    *I have done a lot of research about this style and i’m compiling the information here in a relative and easier to read form, my sources will be referenced at the end of this post*

    I will keep updating this page upon completion of brews and experiments with results and newly discovered information.

    Here is the link to my Recipe post on here.

    Since the late 1800’s brettanomyces has been considered as a spoilage yeast (though in the 17th century it was thought that it gave English ales character) apart from a few styles:

    • Flanders Red Ale
    • Lambics
    • Saisons
    • Some wines – Mostly reds in small amounts to give a complexity or a young wine an ages character
    Brettanomyces produces a number of different fruity esters and spicy phenols that give it distinctive barnyard, horse blanket, funky, Band-Aid flavours. It was predominantly used in secondary fermentation after a saccharomyces cerevisiae (brewers yeast) primary fermentation, this would lead to further attenuation and the production of these funky esters and phenols.

    Since the late 1990’s / early 2000’s Brettanomyces has been used as the primary fermenting strain, it was found that these fermentations produced a beer with predominantly tropical fruit esters and a subdued funk. This is due to the fact that when it doesn’t have to compete with saccharomyces cerevisiae it doesn’t have to adapt to a more hostile environment (lower pH, higher alcohol, less sugars) and it can metabolise the worts sugars into different esters (strain dependent).

    When brettanomyces is fermented in the presence of oxygen (aerobic) it produces ethanol and acetic acid as a byproduct of fermentation. The more oxygen present, the more acetic acid produced and less ethanol. Studies have shown that acetic acid isn’t produced during the yeast growth stage so aeration before inoculation should not have an effect on acetic acid production, so initial aeration should result in faster and healthier yeast growth. However some people have stated that no aeration causes stress on the yeast cells and this causes more byproducts (esters and phenols) to be produced and hence more funk (I will test this theory in the future). From Chad Yakobson’s brettanomycesproject.com dissertation it can be seen that Brettanomyces needs to reduce the pH to around 4 to achieve greater attenuation of sugars (strain dependent ), therefore it could be assumed that this acid is produced to drop the pH to attenuate further. It has also been found that Brettanomyces can produce enough fatty acids in anaerobic fermentation to drop the pH to 4. These acids (often rancid tasting) are then esterified by the Brettanomyces to give the known character. This is why young Brettanomyces beer can often taste rancid, the acids have yet to be esterified.

    Acetic acid is esterified into ethyl acetate which yields pineapple and pear flavours in lower levels while reaching nail polish in higher amounts. So to increase the pineapple flavour in the finished beer you could increase the aeration of the wort which would lead to more acetic acid formation and hence more ethyl acetate being converted, increasing temperature to 28°C would maximise the esterification of acids. So hence not aerating the wort at all and fermenting at the lower end of the strains range would yield less acetic acid and hence ethyl acetate, reducing the pineapple flavour. There are other fatty acids that will be esterified into pineapple flavoured esters.



    From Yakobson’s research it can be said that most strains produce an above threshold level of ethyl caprylate (pineapple, soapy, brandy, apple) and ethyl caproate (sweet, fruity, pineapple, banana, apple or aniseed), these are the 2 most abundant esters produced (from acids produced from fermentation). Upon increased pitching rates, some Brettanomyces strains increase production of these while others decrease it. B. bruxellensis decreases ester production with increasing pitch rates while B. lambicus and B. claussenii increase ester production with increasing pitch rates.

    The same can be said about attenuation but for most strains a pitch rate of 6×106 cells/ml seems to be the most efficient. However, the levels of 4-vinylguaiacol decrease as pitch rate increases, this suggests a lower pitch rate should increase the phenol production and vice versa.

    In malted barley there are 2 abundant acids in free and bound forms; Ferulic Acid and p-Coumaric Acid, they are converted to 4-Vinylguaiacol and 4-Vinylphenol respectively. These 2 compounds are then rapidly converted to 4-Ethylguaiacol (Smokey and spicy) and 4-Ethylphenol (Barnyard and horsey) respectively by Brettanomyces.

    Pilsner Malt contains a higher extractable p-Coumaric Acid to Ferulic Acid ratio than Pale Ale Malt so this should yield a beer with a more ‘funky’ character. Also employing a Ferulic Acid rest should result in an increased extraction of both of these acids. Wheat malt also contains a good supply of free Ferulic Acid and p-Coumaric Acid.

    Under anaerobic fermentation Brettanomyces relies on nitrates in the media, so having increased nitrates will result in a reduced lag time by avoiding the ‘cluster effect’ (redox imbalance) by supporting Brettanomyces’ adaptation to anaerobic conditions and therefore increasing fermentation efficiency. Boiling hops in the wort and dry hopping are a big source of nitrates and hence could increase fermentation efficiency.

    So by using the above information you can tailor your fermentation conditions to acheive your desired flavour profiles. For example, to produce an ester forward tropical beer you could choose B. lambicus and B. claussenii (or possibly a more fruity strain of B. bruxellensis) and slightly aerate the wort so that more acetic acid is produced and therefore more to esterify to ethyl acetate (fruity/pineapple), using a large pitch rate would increase the fruity esters of these strains as would increasing fermentation temperature up towards 28°C and then using Pale Ale Malt instead of Pilsner Malt would result in a lower proportion of p-Coumaric Acid yielding a less ‘funky’ beer.

    For a more funky beer you would want to limit the ester formation by not oxygenating the wort at all before fermentation, using a large pitch of B. Bruxellensis and ferment at the low end of the yeasts range. Then you would want to use Pilsner malt and some wheat malt with a Ferulic Acid rest to amplify the production of the phenols. Limiting ester formation here is key so that they don’t mask the funky flavour of the phenols.

    Brettanomyces doesn’t produce Glycerol (gives beer the silky mouth feel) like saccharomyces cerevisiae does so this can lead to a thin mouthfeel. Adding wheat malt and around 8% flaked grains should add some mouthfeel.

    As Brettanomyces can ferment a number of different sugars up to 9 chains long, mash temperature should not have an effect on attenuation, just the time it takes to attenuate (in the future I will be doing some test batches to see if mash temperature has any effect on ester and phenol production).

    These are my assumptions and interpretations from my research and I will be testing it in my first 100% Brettanomyces brew.

    I will be attempted to lure out the funk from the yeast and subduing the esters while getting the fruit from the hops; I’m thinking of Nelson Sauvin for some tropical flavour with Amarillo supporting, Centennial blending in some floral notes with Stryian Goldings with the earthy spice to blend it with the Brettanomyces funk. Im looking to brew a beer that reminds me of summers day in the countryside (usual West Coast style IPAs remind me of a summers day on the beach).

    I will be seeing if my assumptions are correct and that I can get more funk using the above methods, if successful I will be doing another brew with the exact same blend but this time subduing the funk and maximising ester formation.

    My goal is to run lots of experiments with Brettanomyces over time and learn how to pull out the flavours/characteristics that I require.

    References:
    https://www.sciencedirect.com/science/article/pii/S0958166918300922
    http://brettanomycesproject.com/
    http://www.milkthefunk.com
    https://doi.org/10.1002/jib.5
     
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  2. May 24, 2019 #2

    ChrisRedWills

    ChrisRedWills

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    good luck with that
     
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  3. May 24, 2019 #3

    Braindead

    Braindead

    Braindead

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  4. May 25, 2019 #4

    strange-steve

    strange-steve

    strange-steve

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    Nice post, looking forward to hearing the results of your experiments :hat:
     
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