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Thread: High gravity brewing

  1. #1
    Join Date
    Oct 2002
    Location
    Middle Coast
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    44

    High gravity brewing

    Anyone have any experience with high gravity wort production that will be reduced to a standard beer?

    ie-22P wort to produce two 11P beers.

    Due to limited fermentation space and time constraints I am considering something along these lines, but am unsure how to proceed.

    My thoughts are to let the wort ferment and condition and at racking time to the brite tanks divide in half and top each with an additional 3.5 bbls.

    Any thoughts or comments would be greatly appreciated.

  2. #2
    Join Date
    Oct 2002
    Location
    Tadcaster, Yorkshire, UK
    Posts
    1,085
    Im afraid there is quite abit to consider, but here goes.

    It is not going to be easy to do this level of high gravity brewing and dilution, and basically I recommend you dont, at least to the levels you want to. The big boys dont do it to this extent due to flavour considerations amongst other things. You may get away with a 15 plato wort, but even this may be pushing it for a non automation controlled brewery.

    I assume you are producing a beer with an alcohol content around 4.5 %. First may I suggest that you find a beer of about 9 10 % alcohol, if you can obtain such a beast. Think about the flavour characteristics. The beer is probably quite rich and fruity, with high levels of esters grapefruity type nose, more than normal 4 to 5% beers. If you wish to brew at high gravity and dilute, this is likely to be one of the dominant characteristics in flavour / aroma terms.

    The main problem with high gravity brewing is the yeast & fermentation. You will almost certainly need higher pitching rates to ferment in a similar time scale. At this high gravity, you are likely to have to aerate the fermenting wort considerably to be able to achieve full attenuation of the wort. In spite of that, you will almost certainly end up with unacceptably high levels of esters after dilution, i.e. it will be a different beer. The aeration may cause fobbing over, and increase losses and hygien problems. The air / oxygen will have to be sterile minimise infection pickup.

    The yeast will probably not be reusable for pitching again, and a fresh batch from a normal 11P wort will be required for each batch of high gravity wort. This means you will have to run normal fermentations alongside the high gravity ones. The fermenting wort aeration, if required / used must have its last aeration when the pg is no less than about half original (depends on yeast, fermenting temperatures, wort composition etc.etc.), otherwise you will again get too may unwanted flavoursome by-products produced which carry through to the final beer.

    You may need to make the mash thicker to obtain the final gravity you want without boiling the wort to death. If you make the mash thicker, you will have to raise the mashing in temperature slightly to prevent reduction in attenuation limit this is general, fraid I cannot give any guidelines other than you will probably need to change it by 1 or 2 deg C, but because each brewhouse and raw materials used is different, this is trial and error.

    You may need to increase the amount of liquor treatment salts, but possibly not pro rata for the increase in malt loading. This is to ensure that the final liquor mineral ion balance is the same after dilution as before.

    You will need to increase the hop rate more than pro rata as high gravity worts, and here I am assuming that you currently boil at approx 12 plato, and would wish / need to boil at 23 / 24 plato. This is because hop utilisation is not as good at high gravity as at lower gravities. If you are looking for a definite hop aroma in your final product, then I suspect that this will not come through particularly well, and you may need to increase in FV or in MV or in final pack dry hopping rates.

    The water you use for dilution must be dissolved oxygen free, otherwise you will suffer flavour changes, particularly the production of cardboardy / papery flavours, possibly diacetyl (pear drops), or hazes quite quickly making the beer unsaleable. Dearation with oxygen free CO2 or nitrogen is common. Note the gas must be guaranteed food grade / medical oxygen free.

    Having said all that, if you wish to brew at higher gravity, then try for no more than 15 plato in FV, which probably doesnt get you your capacity increase, but at least all the other aspects indicated above can be controlled reasonably reliably, at least in big breweries. At this gravity, the yeast will be reuseable, and should not require additional aeration, perhaps even using the current aeration rate. You may get away with sufficient aroma from aroma hops in the boil to not worry about dry hopping (which tends to give a different aroma anyway, even when using the same hops). You will probably not have to increase the hop rate by much over pro rata, and should be able to use pretty much the same mash and sparge regime, without major changes to temperatures, stand times, merely reducing the sparge a little and stopping the runoff a little short. You still need to ensure the dilution water is thoroughly dearated and sterile you dont want to introduce infection, particularly at this late stage.

    Phew. Does this help ?

    Cheers
    dick

  3. #3
    Join Date
    Oct 2002
    Location
    Shanghai, P.R. China
    Posts
    158
    I would strongly discourage a dilution post fermentation unless you are diluting with de-aerated water. The big boys will often dilute high gravity up to a point, usually 30%. However they will always use de-aerated water to keep the dissolved oxygen levels low and the shelf-life of the product high. I would prefer to dilute to the fermenter but without extra fermentation capacity you may be in a bit of a jam?

  4. #4
    Join Date
    Feb 2007
    Location
    Brussels, Belgium , Europe
    Posts
    13

    Yeast is stressed by high gravity

    Some yeast strains can produce a significant unfilterable haze (90 angle scattering nephelometry) when submitted to stress conditions (high gravity brewing, high fermentation temperature, etc.). This haze consists mainly of intracellular higher glucans and glycogen particles released during the main fermentation. These particles can undergo some retrogradation and gel formation and can become visible on the microscope. This phenomenon is enhanced when dry yeast is used and in recovered barm beer.

    We have designed a non GMO enzymatic complex to speed up the fermentation rate and to get a brighter beer. This complex called Labilase decreases the lag time before the start of fermentation, speeds up the fermentation rate (P/day) and leads to 40-50% better results concerning the turbidity measures (90 and 25).

    Depending on the dosage rate used, Labilase can also increase the apparent attenuation up to 90% (dosage rate 0,25 g / P / Hl). If you do not want to increase the final attenuation there could be 2 solutions: to use a lower dosage rate or to stop the fermentation by cooling once the desired attenuation is obtained and the diacetyl level is low enough. This last solution is used in 2 breweries in Western Europe. Labilase is totally destroyed after 1 pasteurization unit.

    Best regards

    Pablo Alvarez
    www.cbsbrew.com

  5. #5
    Join Date
    Feb 2007
    Location
    Brussels, Belgium , Europe
    Posts
    13

    Yeast is stressed by high gravity

    Some yeast strains can produce a significant unfilterable haze (90 angle scattering nephelometry) when submitted to stress conditions (high gravity brewing, high fermentation temperature, etc.). This haze consists mainly of intracellular higher glucans and glycogen particles released during the main fermentation. These particles can undergo some retrogradation and gel formation and can become visible on the microscope. This phenomenon is enhanced when dry yeast is used and in recovered barm beer.

    We have designed a non GMO enzymatic complex to speed up the fermentation rate and to get a brighter beer. This complex called Labilase decreases the lag time before the start of fermentation, speeds up the fermentation rate (P/day) and leads to 40-50% better results concerning the turbidity measures (90 and 25).

    Depending on the dosage rate used, Labilase can also increase the apparent attenuation up to 90% (dosage rate 0,25 g / P / Hl). If you do not want to increase the final attenuation there could be 2 solutions: to use a lower dosage rate or to stop the fermentation by cooling once the desired attenuation is obtained and the diacetyl level is low enough. This last solution is used in 2 breweries in Western Europe. Labilase is totally destroyed after 1 pasteurization unit.

    Best regards

    Pablo Alvarez
    www.cbsbrew.com

  6. #6
    Join Date
    Nov 2005
    Location
    Tokyo Japan
    Posts
    209
    I had heard that the guys at Choc Beer brew their beers a little high for their out-of-state sales, then dilute the same beer to 3.2% to be able to be sold in-state at supermarkets and convinience stores, as Oklahoma one of those states that still holds on to its old anti-alcohol ways. It's not quite what you're talking about doing, but it might be worth contacting them to see how they go about it...if they do indeed do this at all! Their 3.2% bottled and draft product is still quite good. I think I recall their brewer posting around here before.

    Cheers
    www.devilcraft.jp
    www.japanbeertimes.com

  7. #7
    Join Date
    Mar 2008
    Posts
    120
    Years ago I had a very high volume brewpub. 2kbbl/yr w/a 10bbl rig.
    We had 12, 10bbl fvs and 2, 40s.
    Two of our top sellers accounted for over 65% of sales on and off premise, they were both in the 11P range.

    Our strategy was fairly simple. Into the 40bbl tanks we would cast 10bbl water acidified and at sanitizing temp. the day before. This water would cool overnight.
    The next day we would run three batches of 15P into the tank yielding our standard gravity. The full charge of yeast was added to the first knock out and both of the first 2 kos O2 was added. The beer from this style of brewing was virtually indistinguishable from batches produced 1:1.

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