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Fermentations stop at ~4.2% Plato

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  • Fermentations stop at ~4.2% Plato

    I`ve got a problem with primary fermentation. Primary fermentaion in last few batches stopped at 4.0-4.3% Plato (1.016). Mash rests were 63-64 degrees Celsius (145-147F), mash out at 75 degrees Celsius (167F). I used Fermentis yeast, US-05 and S-04. Fermentation temperature 18-19 Celsius or 64-66F.
    Have you any assumption why fermentation stops? Thanks for advance
    Last edited by zaporozsky; 11-21-2018, 03:29 AM.

  • #2
    Hello, we have been having the same issues, we monitor attenuation and it seems lately that fermentis yeasts arent reaching our previous targets. Major problems when brewing an imperial stout or such. It sucks but it may be due to batch production problems in Fermentis and not because your/our protocols. Hope we can all sort it soon.
    Good luck
    Jose Argudo
    Head Brewer
    3Monos Craft Beer
    Malaga, Spain


    • #3
      I've been having the same problem with fermentis recently, specifically their s-04. Always pitched fresh


      • #4
        thanks guys!


        • #5
          Continue our investigation

          My water profile shows low calcium — 5 mg/L. Calcium is important for enzymes during process of mashing. If calcium is not enough, enzymes can leave a lot of unfermented sugars. What do you think about my hypothesis?


          • #6
            As far as I know, malt has enough calcium for conversion purposes and additional calcium is added mostly to aid yeast flocculation in the fermenter. A poor conversion would result in a low OG for the grain bill. Unless α - amylase is more sensitive to low calcium than β, there wouldn't be a reason to suspect that.

            The other thing to look at is mash temperature since too high would give lenghtier sugar chains.

            Anyway, I have also experienced FG of 1.016 - 1.014 when using S-04 when OG is about 1.062-1.058 for enough time. S-05 consistently goes down to 1.010 here. Both are classified as mid-attenuation by Fermentis which is odd. At this point I have credited it to the higher flocculation rate of S-04 which means it goes out of suspension more quickly.


            • #7
              Forced ferment

              I know you put you rest temps in your original post, but any chance you've tried a forced ferment to rule out a problem in the mash? Follow up, are you tracking gravity daily, are you checking pH? Is this a beer you brew frequently? Lots of questions but there's lots of places to look for a problem like this.


              • #8
                "As far as I know, malt has enough calcium for conversion purposes and additional calcium is added mostly to aid yeast flocculation "

                Not always true. Calcium is needed for phosphate and oxalate precipitation in the mash (amongst other uses), which then releases hydrogen ions and so reduces the pH to one better suited for the amylases in particular. Traditionally, the lack of ability to add mineral salts to the mash in pilsener lager style brewing areas meant that to get the correct pH, the brewers added lactic acid from lactic acid mashes. I have also seen horrible sediments and hazes / suspended bits like snow in (lager) beers brewed without sufficient calcium. On adjusting to about 100 ppm in the mash liquor, this left about 25 ppm in the final beer - eliminating these hazes and sediments. At the time I was in packaging / QA and so don't know if it also improved yeast flocculation, but it cannot have harmed.