Rehydrating Yeast

Discussion in 'Beginners Brewing Forum' started by Craigerrr, Apr 30, 2019.

  1. Craigerrr

    Craigerrr Well-Known Member

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    Is there any reason why I couldn't rehydrate yeast a day in advance, refrigerate it, and take it out to warm up to pitch temp on brew day? I typically use US-05, or S-04 dry yeasts.
     
  2. Hogarthe

    Hogarthe Well-Known Member

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    As long as you keep it sanitary it should be fine.
     
  3. Nosybear

    Nosybear Well-Known Member

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    Second that.... But if you're going to do that, why not mix up a small starter and use only one of the packages? 24 hours AND rehydrating to the starter would give you a nice, healthy batch of yeast while using only one package.
     
  4. Drewfus1

    Drewfus1 Member

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    Alternately, you could just pitch the yeast directly into the fermentor. Fermentis states that you can do just that: "Pitch the yeast directly in the fermentation vessel on the surface of the wort at or above the fermentation temperature.
    Progressively sprinkle the dry yeast into the wort ensuring the yeast covers all the surface of wort available to avoid clumps."

    I've never rehydrated dry yeast. Fermentation always starts promptly, the beers fully attenuate and I don't get any off flavours. If its a high gravity wort you may want two packets or you could make a starter. Otherwise, rehydrating dry yeast is just another complicating step that has the chance of introducing an infection.
     
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  5. Nosybear

    Nosybear Well-Known Member

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    And so it begins...
     
  6. J A

    J A Well-Known Member

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    The downside to pre-hydration and cooling is that the yeast will go dormant and have to start over in terms of metabolism. If you're just rehydrating, it only takes a very small amount of time. I don't see any advantage in rehydrating ahead of time.
    As for whether to rehydrate or not, the debate has played out many, many times. There are always some who say it's just as good to skip rehydration but I know that when I put a foaming mass of live, active yeast in my wort, it starts quicker and even if there's ultimately no other difference, I'll take that because it ensures less time that the wort is vulnerable to colonization by random micro-organisms in the environment.
     
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  7. The Brew Mentor

    The Brew Mentor Well-Known Member

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    It's interesting that what is stated on the yeast pack and also in most kit instructions is different than what may be on the manufactures websites.
    Fermentis' site will say it's fine to "dry pitch", but then gives proper re-hydration instructions as well.
    I've always understood that the yeast, in a dried state, are very fragile and susceptible to damage. Logic would say that proper re-hydration should give them a better start.
    Do what works for you, but I would feel better with a "safer" start.
    I also see a huge difference in yeast after the 1st generation and feel it more reflects what the descriptions of it are.
    Cheers,
    Brian
     
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  8. Nosybear

    Nosybear Well-Known Member

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    "Safest" given the OP's post, would be to simply pitch the two packets of yeast without rehydrating. Brew Mentor speaks of the science behind rehydrating and I tend to like to maximize my pitch. Sometimes two packets of rehydrated yeast are just enough for a lager, last brew, a middle-of-the-road blonde, I just sprinkled. Back to my mantra: Know why you are doing a thing. Craigerr had several options. I wouldn't rehydrate and let the yeast stand overnight, as he originally suggested. Two packets, simply sprinkled on top of the wort would be enough for the beer he's brewing. If he's going to let it stand overnight, I'd do a small starter, a half to a liter, and really have the yeast revved up when I pitched it. But then if I thought I needed the higher pitch rate, I'd rehydrate the two packets when I started cooling the wort. Given decent sanitation, none of the options are particularly risky so it comes down to brewer's preference on this one.
     
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  9. Craigerrr

    Craigerrr Well-Known Member

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    Appreciate all of the responses.

    Why do I rehydrate?
    I ferment in carboys, and getting the dry yeast in there is a little tricky. Some always seems to stick to the side. I would use a funnel, but it would get wet when I sanitize it.

    Why am I asking about getting it ready the day before?
    I always forget to boil, and cool the water. So I end up rushing around.

    I have only ever pitched one package of dry yeast, but I have often made starters when using liquid yeast.

    I guess the best solution is to remember to get the water boiled and cooled ahead of time.
     
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  10. Please Delete!

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    Just to put in my noob experience. I nuke the water at the start of my brew day and then by 15 mins left my boil its cool enough to add the yeast. The last 2 brews I have used my stir plate and yeast nutrient. Not really doing a starter just something i tried and have gotten 4 points lower fg then expected both times. ( probably just the added nutrients )
    I don't see any reason not to re-hydrate it only has neutral or upside no real downside.
     
  11. J A

    J A Well-Known Member

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    For over a hundred brews, I've been rehydrating with filtered tap water run directly into a sanitized, new solo cup and covered immediately with sanitized foil. If you need to boil your water in order to rid it of bacteria, you've got bigger problems than anything that happens to your beer. :eek:
    Contamination is far less likely to come from water fresh out of your tap than from any number of other sources throughout your process. Not to mention the fact that the concentration of yeast cells in the cup of water is millions, if not billions, of times higher than anything that could possibly be in there with it. The yeast will win every single time.
     
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  12. Trialben

    Trialben Well-Known Member

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    I do both:D!
    If I'm gunna use once in she goes dry.
    If I'm looking at reusing that strain I always wip up a large starter pinch 500ml for next brew and pitch resulting slurry.

    I see in your circumstances Craig that pitching dry yeast into a carboy would be a pain in the bum so a liquid pitch seems like a goer to me.

    John's starter tip sounds like a goer to me.
     
  13. Craigerrr

    Craigerrr Well-Known Member

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    Thanks all, much appreciated
     
  14. J A

    J A Well-Known Member

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    Making a starter is fundamentally different from rehydrating. The notion with rehydration is that the yeast cells are dessicated and dormant and are being allowed to "reinflate" with H2O before getting back to the business of metabolizing and reproducing.
    With dry yeast, there's a medium of mineral-rich nutrient that's created from the stuff that the yeast cells are packed in. It just allows a bit of a transition before the cells encounter the real food source and can result in stronger cells and healthier organisms for a higher cell count.
    With a 500ml starter, it's not particularly different from pitching dry directly into the wort but you're getting the benefit of several generations of reproduction to massively increase the cell count.
     
  15. The Brew Mentor

    The Brew Mentor Well-Known Member

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    From the Lallemond website;
    https://www.lallemandbrewing.com/en/canada/products/brewing-yeast/
    Also, download their rehydration guide from the link above

    Upon rehydration, dry cell membranes undergo a transition from gel to liquid crystal phase. Rehydration in sterile water is recommended prior to pitching into wort in order to reduce stress on the cell as it transitions from dry
    to liquid form. Proper rehydration of dry yeast will produce a highly viable and vital liquid slurry.
    The following effects have been observed with nonrehydrated yeast under specific brewing conditions:

    • Longer diacetyl stand
    • Longer fermentation time
    • Longer lag phase
    • Stuck fermentation
    • Poor utilization of maltotriose

    FOUR IMPORTANT FACTORS TO CONSIDER DURING REHYDRATION

    1. MEDIA TYPE
    Rehydration in undiluted wort causes osmotic stress to the yeast. Sterile water should be used for rehydration, but distilled water should be avoided.

    2. TEMPERATURE
    The ideal rehydration temperature is different for ale and lager strains. Ale strains should be rehydrated at 30-35°C (86-95°F), whereas lager strains should be rehydrated at 25-30°C (77-86°F).

    3. TIME
    The rehydration period should be between 20-60 minutes. A decrease in viability and vitality will result from extended storage periods after rehydration. Once rehydrated, the yeast can be pitched into wort. To avoid shocking the yeast, the temperature of the yeast should be reduced gradually to within 10°C (18°F) of the wort temperature. This can be achieved through additions of small volumes of wort to the rehydrated yeast slurry.

    4. SANITATION
    Care should be taken to avoid contamination during rehydration. The rehydration vessel should be autoclaved or sanitized before use. The outside of the yeast pack and the scissors/knife should be soaked in sanitizing solution prior to opening.
     
  16. Hogarthe

    Hogarthe Well-Known Member

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    You could just use bottled water to rehydrate. It's clean so you don't need to boil it. Then you won't forget to boil it.
     
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  17. thunderwagn

    thunderwagn Well-Known Member

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    I am the same. I use water straight from the tap.
     
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  18. Bubba Wade

    Bubba Wade Well-Known Member

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    I had come down with the flu during one batch between the time I put the wort in the fermenter and when it cooled to pitching temperature. I asked my wife to put in the yeast. She pulled out the airlock and dumped the yeast in. No problems. It doesn't really seem to make much difference whether I re-hydrate or not.

    An interesting side-note: I asked my wife to put in the pack of German Lager yeast. She saw a pack that said German and dumped it in. Turned out that she had added the German Ale yeast, which fermented surprisingly well at 48 °F.
     
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  19. atoughram

    atoughram New Member

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    From the Fermentis website in their brochure "Tips and Tricks"

    "TODAY A STUDY DEMONSTRATES THAT THE USE OF ACTIVE DRY YEASTS (ADY) is very easy and does not necessarily include a rehydration step. To the contrary, the ADY can advantageously be immediately put in contact with the wort into the
    fermentation vessel (direct pitch). Several rehydration and direct pitch conditions do not show any significant differences in terms of the viability and the vitality of the ADY."

    The rep that I talked to and a homebrew meeting claimed that you kill yeast rehydrating them in water.

    Each to their own I guess - your results may vary ;)
     
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  20. Trialben

    Trialben Well-Known Member

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    Each of his/her own as long as the beer tastes good that's what matters. There is more than one way to skin a cat and more than one way to brew a beer. To Quote another brewer on this forum I think (noseybear) what is it ask two brewers one question get two different answers! Man I love this hobby LOL:p!
     
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