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Thread: Very Poor Attenuation

  1. #1
    Join Date
    Jul 2014
    New Zealand

    Very Poor Attenuation

    Hi Brewers

    Can anyone help me out with a head-scratcher? I recently brewed a contract Red IPA for another brewery, 1400L batch with 280KG base malt and 86KG of various crystal malts. Water additions were our normal for a pale ale. pH was about right, Conversion was normal or maybe a bit above average. Mash temp was 67'C. We used 600g Safale US-05. It has stopped dead at 1.027. We extracted a sample and over-pitched with US-05 and it went nowhere.

    I personally think that there's too much crystal in this recipe but nowhere near enough to explain this under-attenuation.

    Does anyone have any ideas?

    Cheers and Beers


  2. #2
    Join Date
    Oct 2002
    Chesterfield, UK
    It sounds as though you mash temperature is too high, though I am surprised the AL appears to be as high as it is.

    Any other major changes from your normal procedures such as liquor to grist ratio? High liquor to grist will generally increase the AL, though again, I would be surprised if anywhere near that much. All malts evenly mixed in to ensure consistent mash temperature and enzyme distribution?

    Pitching rate OK by my usage standards.

    Otherwise - perhaps a one off daft mistake - such as killing off most yeast by forgetting to cool wort or water down adequately before mixing in, or adding to hot wort in the FV during wort transfer

  3. #3
    Join Date
    Jun 2011
    Richmond, VA.
    was there any simple sugars added to the wort in the kettle? i have see fermentation stall out if there are to much simple sugars. yeast will tend to go after simple sugars and not produce the enzymes to break down other sugars.

  4. #4
    Join Date
    Jul 2014
    New Zealand
    Thanks for the tips folks. I've dumped the brew after a massive slurry re-pitch failed to do anything. I've had a complete overhaul of our processes taking into account your advice (bigger liquor to grist ratio in particular) and hopefully won't encounter any more issues.

  5. #5
    Join Date
    Mar 2013
    Milwaukee WI

    Poor Attneutation

    Could be the amount if specialty in there as well, i know we start to see attenutation only out to around 65-75% using US-05 at specialty malt additions around 25% of the grist bill (beers where specialtes make up less than 10% of the grist we have no problem achieving 85-90% attenutation with US-05). Another quirk of US-05 we have noticed is that regardless of how fermentable our wort is and how accurate our viabilities and pitching are, no matter what we can't seem to get US-05 to attenuate (consistently, at least) past 9-9.5% ABV, so depending on the ABV you might have pushed the yeast to its limit, we now brew with either Dry English Ale yeast or Scottish Ale yeast for any beers higher than 20 Plato to be sure we get the attenutation we are looking for on hihg plato beers.

    Just my two cents, hope this helps

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