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Rehydrating dry yeast: what to look for.

Discussion in 'General Brewing Techniques' started by ballantynedewolf, 16/4/19 at 12:34 AM.

 

  1. ballantynedewolf

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    Posted 16/4/19 at 12:34 AM
    I rehydrate my dry yeast in 30C mineral water before pitching. Sometimes the grains sink v slowly and there's great foaming, other times they sink fast and sit there seemingly dormant, as just happened with 2 packs of MJ French Saison. I'm suspicious this yeast is in poor condition. I got it from a shop I haven't been to before.
    Ferm has started within 12 hrs as it always does.
    Are there reliable signs in the rehydration jar that tell me if it's good yeast or not?
     
  2. wide eyed and legless

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    Posted 16/4/19 at 1:07 AM
    I have found that different yeast have different behaviour, some on the stir plate will start foaming others seem to do nothing. I don't rehydrate or aerate any more and everything still goes as normal. I have been sent some dry English ale yeast from China and it has the same instructions as Fermentis not to aerate. I don't think it makes any difference to rehydrate as long as the temperature of the wort is comparable to the temperature of the rehydrated yeast.
     
  3. ballantynedewolf

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    Posted 16/4/19 at 7:35 AM
    Like you, I make OK beer, and have done so without rehydrating. But if I knew the yeast was top shelf, then my beer would be maybe better, and certainly more predictable.
    Everything I've read about rehydrating says it should foam up, so when it doesn't I'm concerned.
     
  4. wide eyed and legless

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    Posted 16/4/19 at 7:41 AM
    Don't bother with the rehydrating, I can't recall which yeast didn't foam up I do know that the Fermentis SO4 did and CML yeast did, could have been a pseudo lager yeast or US05 which didn't foam.
     
  5. ballantynedewolf

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    Posted 16/4/19 at 7:58 AM
    We're going to have to agree to disagree. There are excellent reasons to rehydrate and it's easy to do. But I totally respect your decision not to.
     
  6. wide eyed and legless

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    Posted 16/4/19 at 8:59 AM
  7. Schikitar

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    Posted 16/4/19 at 9:38 AM
    Yeah I don't rehydrate anymore either, no real need, if doing a big ABV beer (or have more volume than a typical batch) just use two packets..
     
  8. jollster101

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    Posted 16/4/19 at 12:26 PM
    Hey Weal and Schikitar,

    Do you guys predominantly only use dried yeast when brewing?

    If you don't then what do you do with liquid yeasts? I am only 4 FWK's in and so far every yeast has been dried which I have rehydrated. Curious as to what needs to happen when (and if) I use a liquid yeast for the first time.

    Cheers
     
  9. wide eyed and legless

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    Posted 16/4/19 at 2:08 PM
    With the liquid yeasts I will make a starter and have it on the stir plate for an hour before pitching, the dried yeast is past the oxygen stage this is an excerpt from a reply from Fermentis on Pro Brewer forum.

    We don’t recommend to aerate the wort in normal conditions. The dry yeast has been produced and dried with a specific know-how of the Lesaffre Group, in order to maximize the Ergosterols content of the cells. It allows the yeast to ferment well.
    However, you could aerate the wort in particular cases, for example if you recycle the yeast, maybe the 02 will be limited after the 4th or 5th pitch.

    So even repitching saved dried yeast it still does not need oxygen until after the 4th or 5th pitch.
     
    Schikitar likes this.
  10. Schikitar

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    Posted 17/4/19 at 12:34 AM
    For me it really depends on the brew. If I'm doing a bigger ABV (+6%) brew then I like to build a liquid starter on my custom made stirplate OR it might be that I just want to try a particular strain rather than something more generic like with the dry yeasts. I build my starters 24-36 hours before pitching - if you step them up or simply build a big starter then you can split it at this point and save some for the next brew (this is good as you don't have to harvest from the fermenter with all the crud, not that that is a show stopper). If I'm just quickly throwing an impromptu brew together and it's no bigger than say 5.5% then I just grab a packet of dry (usually S04 or M36) and just sprinkle that straight in, in many ways this is much easier but I like to experiment with every brew, also building little mini beers (starters) is kinda fun. Even though I mention the ABV limitation that's just something I've been doing lately - a dry yeast, like M36 for example, will chew through a big beer just fine, you just have to up the amount you pitch (at which point the cost starts to equalise with liquid yeast which you can invest in once and split over many batches, economics)..
     
  11. jollster101

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    Posted 18/4/19 at 3:19 AM
    Thanks for the replies gents. One of the biggest time consumers for me when I am doing my FWK's is waiting for the temperature of the water I have boiled to come down to 30-35C before rehyrdating the yeast.

    It would be a massive bonus not to have to do that if still able to yield the same results.
     
  12. Schikitar

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    Posted 18/4/19 at 3:28 AM
    Give it a go next time, just sprinkle yeast in and see what happens, don't forget to report back with your findings! :)
     
  13. jollster101

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    Posted 18/4/19 at 5:55 AM
    Will do. One last one, is there a need to use double dried yeast if not rehydrating or does it make no odds (assuming not doing a high gravity beer)
     
  14. Schikitar

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    Posted 18/4/19 at 2:09 PM
    As you are doing FW kits then one packet of well maintained dry yeast will be just fine! It may be a little slower to get going but it will go. If you overlap your brews then you could potentially pitch some slurry from one brew to the next, that should take off pretty quickly and you get even more bang for buck. Just be super good with sanitation and handling as any brewer should..
     
  15. hotmelt

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    Posted 19/4/19 at 2:09 AM
    If you've got a vacuum sealer make up a small bag and add the water,seal and cool in the fridge.When cool enough,open and add the yeast,reseal and leave to rehydrate.You could also add some wort to the bag to make a starter.
     
  16. mabrungard

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    Posted 20/4/19 at 4:45 PM
    Rehydration is semi-optional. In ale brewing, the pitching rate provided by the typical homebrew sachet is OK. But its definitely not when dealing with lager brewing. The low wort temperature definitely reduces the hydration of the yeast and ultimately, the start of and progression of fermentation.

    I sometimes pitch dry yeast into my ales and they perform well. However, I found out the hard way when brewing a German Leichtbier (1.040 SG), that pitching dry yeast on a 10C wort does severely delay the start of fermentation. It took almost 3 days for my Tilt to report any gravity reduction. Fortunately, my brewing practices are apparently clean and the beer eventually fermented out and its clean. But I now strongly recommend that any lager brewers be sure to rehydrate your dry yeast in 30C water that has decent mineral content (using epsom salt in RO water is very good too).
     
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