Re-hydrating Yeast

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Nicknack

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I just brewed my third batch yesterday which was a 5 gallon Falconer's Flight Brewer's Best extract brew kit. After much reading about re-hydrating yeast, I gave it a go for the second time.

With my last batch, I started to re-hydrate the yeast towards the end of my boil. The issue was that the temperature of the yeast was considerably higher than the wort. I added some wort to the yeast to cool it, which helped, but still a good bit higher. According to what I've read, the yeast needs to be within 5 degrees of the wort before pitching. In order to accomplish this, I had to wait 15 minutes or so which I doubt was very good for the wort to sit there waiting.

With yesterday's batch, I decided to start re-hydrating my yeast much earlier so the wort wouldn't have to sit and wait. Although, maybe I did it too early because it was going from a creamy mixture to sort of a large bubble on top.

Is it really necessary to get the yeast to within 5 degrees of the wort before pitching? Perhaps it's because I'm just a newb, but having to juggle this while trying to focus on my brewing isn't ideal. I actually had a boil over yesterday because I was working on re-hydrating my yeast and took my eyes off the stove for a couple minutes. If the temperature is important, how do others work the timing?
 
I start to re-hydrate with about 20 min left in the boil. I sprinkle the yeast into the water and let sit 15 min. Then I stir the yeast and let sit another 15 min. By then my wort is chilling and I pitch within 15-30 min. Never bothered to check the temp of the yeast, and after sitting for that long it has to be around room temp. Works fine for me.
 
You want to rehydrate the yeast. The bubble on top is fine, think of as a viability test. You can rehydrate before you start your boil and let it rest loosely covered with a piece of aluminum foil. It will get to room temp and after you cool the wort to 65-68 you can just pitch the slurry and call it a day. You don't want to shock the yeast, which is why you want to keep it close to wort temps.. Hot wort can kill yeast and cool wort can cause it to lag long than you want allowing other organisms a head start. It's probably optimal to have your slurry a degree or two below your wort at pitch time but not critical.
 
I rehydrate with about 20 - 30 minutes before the end. By the time my worts chilled, its ready to pitch. If you have a boil over that late in your boil. Your boiling too hard. Measure out 100ml of water, sprinkle yeast in and forget. I try to match the temperatures but sometimes im too lazy and put it in. However it is always within 5 degrees C so as not to temperature shock the yeast but i have heard 10 degrees C is not an issue. Ive never pitched with that differece though
 
I've most often red in manufacturers PDF's that the rehydrate should be within 10 degrees of current wort temp, not 5. Within 5 degrees might be better, but 10 degrees is the norm they give. I do believe I've read the times wrong though. I was sure it was sprinkle on dry yeast, wait 15 minutes. Then stir & wait another 15. I read one of them again, & it was said to sit another 30 minutes after those first two steps. Gonna look at'em again...:confused:
 
I asked Danstar about rehydration timing. They emailed me this:
"Our technical manager suggests that you don't go longer than 30 minutes after the start of rehydration before pitching the yeast into wort as the yeast needs nutrients. If there is a delay you could actually add more wort to the rehydration water to give the yeast something to eat while you are waiting to pitch it, so long as it isn't too hot."
 
Those that responded that you re-hydrate at xx time, are you talking about when you actually add the yeast to the water? The reason I ask is that the instructions that I have about re-hydrating yeast recommends that you boil for 15 minutes. In my mind, that seems like a long time to boil such a small quantity of water. You all do boil the water before introducing it to the yeast, correct?
 
Those that responded that you re-hydrate at xx time, are you talking about when you actually add the yeast to the water? The reason I ask is that the instructions that I have about re-hydrating yeast recommends that you boil for 15 minutes. In my mind, that seems like a long time to boil such a small quantity of water.

I've never boiled the water that long and I see no reason to. Before I begin the boil of the wort, I put the desired amount of water (plus a bit more to account for boil off) into a pyrex measuring cup and nuke it until it boils plus 2 min. After, I cover it with a piece of foil sprayed with StarSan and leave it to cool on the counter while I brew. I check it when I begin chilling the wort and put it in the fridge or freezer if needed to get it down around 85-90*F which is a good rehydration temp.


You all do boil the water before introducing it to the yeast, correct?

If you boil after adding the yeast, you'll have 100% dead yeast.
 
I've never boiled the water that long and I see no reason to. Before I begin the boil of the wort, I put the desired amount of water (plus a bit more to account for boil off) into a pyrex measuring cup and nuke it until it boils plus 2 min. After, I cover it with a piece of foil sprayed with StarSan and leave it to cool on the counter while I brew. I check it when I begin chilling the wort and put it in the fridge or freezer if needed to get it down around 85-90*F which is a good rehydration temp.

Don't you risk shocking your yeast pitching it around 85-90 degrees if your wort is chilled to about 70 degrees? The instructions that I've been following recommends getting the yeast within 5 degrees of the wort. After looking more at other directions for re-hydrating yeast, I've seen within 10 degrees as well.

The instructions that I have been using:

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1. Start off by boiling ¾ cup water on your stove. Regular tap water will work fine here. You need to boil this water for 15 minutes to sterilize it.

2. Slowly pour ½ cup boiled water into a sanitized bowl. Sanitize a thermometer and a large piece of foil. Use the thermometer to monitor your temperature, and cover the bowl with the sanitized foil.

3. Wait for the temp to drop to 105 F, then gently sprinkle the dry yeast on top of the water. Avoid creating clumps of yeast. Cover again with your foil, and let this sit for 15 minutes.

4. Carefully stir your yeast with a sanitized spoon or fork. Your yeast should now have a very thin creamy texture. You now need to carefully adjust your yeast to close to the same temperature as the wort or starter that you'll be pitching into. The best way to do this is to add cooled wort to the yeast 1 tablespoon at a time. Use your sanitized thermometer to monitor your temperatures. Once you're within 5 degrees of your wort temperature, go ahead and pitch your yeast.

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I would think that as long as I use bottled water (instead of tap) I wouldn't need to boil it for 15 minutes like the directions recommend. Thoughts?

The biggest challenge I have had with following the instructions above is getting the yeast to within 5 degrees of the wort. I believe next time I will shoot for within 10 degrees which will be much easier to do. Also, I like the suggestion of putting the yeast mixture in the fridge to cool it down faster, assuming that is okay to do with the yeast.
 
Don't stress too much over this. It's good to rehydrate; especially if your making high ABV beers, but you don't need to do it. You don't want the yeast to get shocked going from one temperature to another, so you can add some hot wart to the cold yeast/water, to bring the temperature up or down. But don't stress over this, just throw it in dry if you want. It is good to boil the water and kill the bugs for 20 min, it just has to be on a low simmer. It would make a bigger difference if you wanted to invest in a oxygen kit with a oxygen stone.
 
I'm one who doesn't re-hydrate dry yeast. I just sprinkle on top. I tried re-hydrating but found no difference. Actually for me, re-hydrating provided a longer lag time than just pitching.
 
That's where matching the temp of the rehydrate to within 10 degrees of wort temp comes in. Otherwise, the yeast shocks to some degree, & it takes longer for visible fermentation to start. It should take less time, not more.
 
I'm one who doesn't re-hydrate dry yeast. I just sprinkle on top. I tried re-hydrating but found no difference. Actually for me, re-hydrating provided a longer lag time than just pitching.

+1

I almost never rehydrate my dry yeast. I simply sprinkle it on top of the wort and give it a good stir. Never had problems doing that with US-05 or S-04. Other dry yeasts may behave differently, but probably not.
 
It is good to boil the water and kill the bugs for 20 min

Yes, being that I was using tap water, I understand the need to boil for 15-20 minutes. However, if I use spring water, do I really need to boil for more than a minute or two? This is the water that I use for my batch (without boiling it).
 
I just boil my water at the beginning of the brew day and let it sit/cool during the brew. AFter cooling the wort, I microwave my previously boiled water for 20 seconds which heats it to about 100 degrees. I add a pinch of yeast nutrient to that water. I then pour the yeast on top of that warm water solution and let it sit for 15 minutes (during which I use my air stone to aerate the wort). After 15 minutes, I pour in a bit more cooled (previously boiled) water into the yeast solution to get it to 75 or so degrees, stir with a sanitized spoon and add to aerated wort.
 
+1

I almost never rehydrate my dry yeast. I simply sprinkle it on top of the wort and give it a good stir. Never had problems doing that with US-05 or S-04. Other dry yeasts may behave differently, but probably not.

I brewed two batches a couple weeks ago using S-04- just sprinkled the yeast on top. Within 8 hrs the yeast was rocking. And that was just shaking the carboy for 3 min. I have since gotten an oxygen wand with a .5 micron stone but have not used it yet.
 
I just boil my water at the beginning of the brew day and let it sit/cool during the brew. AFter cooling the wort, I microwave my previously boiled water for 20 seconds which heats it to about 100 degrees. I add a pinch of yeast nutrient to that water. I then pour the yeast on top of that warm water solution and let it sit for 15 minutes (during which I use my air stone to aerate the wort). After 15 minutes, I pour in a bit more cooled (previously boiled) water into the yeast solution to get it to 75 or so degrees, stir with a sanitized spoon and add to aerated wort.

Going back to my earlier question regarding boiling the water - are you boiling because you are using tap water? If I use spring water, I could skip this step, correct? Being that this is the same water that is in my wort (which I didn't boil either because it's bottled) I would think that they would be treated the same.
 
Yeah, I boil just because I use tap, but if I had bottled water (and sometimes I do) I don't bother to boil it - I just warm it up for rehydrating.
 
You can rehydrate before you start your boil and let it rest loosely covered with a piece of aluminum foil.

That's not recommended. The manufacturer cautions that you don't want to leave the rehydrated yeast sitting around waiting for too long, as after it's been reconstituted, it rapidly depletes is reserves and needs to be pitched into the main wort. Sprinkle and leave it for 30 minutes, then stir for 30 minutes, then pitch immediately. Starting the process before you've even started boiling would have your yeast ready too early.
 
Yeah, I boil just because I use tap, but if I had bottled water (and sometimes I do) I don't bother to boil it - I just warm it up for rehydrating.

I tend to use bottled water still (as I do not have all my ph equipment bought and all that, and the strips say ph 5), but what should the temp of the water be on warm-up? I plan to do my next brew soon and will need to rehydrate my US-05 due to my OG planned being 1.092ish. I want max cellcount out of it (even got a 2nd packet after feedback from guys here)
 
The guidelines that I have says to add yeast to the water when it reaches 105 degrees (when cooling down from a boil). Therefore, as eadavis80 stated earlier, heating up to about 100-105 degrees should be fine as far as I understand it.
 
You all do boil the water before introducing it to the yeast, correct?

I don't. I just collect it from the tap, mixing hot and cold until the temperature is pretty much right on 85° F, then pour off the excess to get me down to the desired volume (115 mL for 1 packet, 230 mL for 2), drop in a sanitized stir bar, sprinkle in the yeast, cover with sanitized foil, wait 20 minutes, then turn on the stir plate, wait 30 more minutes, then pitch.

Never boiled my rehydration water, never had an infection (knock on wood).
 
I don't. I just collect it from the tap, mixing hot and cold until the temperature is pretty much right on 85° F, then pour off the excess to get me down to the desired volume (115 mL for 1 packet, 230 mL for 2), drop in a sanitized stir bar, sprinkle in the yeast, cover with sanitized foil, wait 20 minutes, then turn on the stir plate, wait 30 more minutes, then pitch.

Never boiled my rehydration water, never had an infection (knock on wood).

You must have decent water. My tap water is full of chlorine. I think next time, to simplify things, I will just use bottled water then...

1. Heat about a 1/2 cup in the microwave until about 90 degrees.
2. Sprinkle yeast on top.
3. Wait for 15 minutes. Then stir.
4. Pitch re-hydrated yeast in wort (assuming the temperature is down around 75 degrees or so). If not, I will add a little cold water to get the temperature down where it needs to be.

With my last batch, I was focused too much on the re-hydrated yeast that I took my eyes off my wort for a couple minutes and as a result, experienced a hot, sticky mess (over boil). I like to simplify things when possible. :)
 
I'm on city water, so it's got chloramines in it. I treat my brewing liquor with Campden tablets, but I don't bother with the rehydration water. The chloramines in the municipal water mean I don't have to boil it (there's nothing living in it), but it's such a small amount that I'm not worried about the chloramines affecting the flavour of the beer.
 
I'm on city water, so it's got chloramines in it. I treat my brewing liquor with Campden tablets, but I don't bother with the rehydration water. The chloramines in the municipal water mean I don't have to boil it (there's nothing living in it), but it's such a small amount that I'm not worried about the chloramines affecting the flavour of the beer.

Good point. Perhaps I will just use tap water which would obviously save on bottled water and allow me to skip the microwaving step as well.
 
On a related note... why do you think the instructions in my Brewer's Best IPA kit were very explicit NOT to re-hydrate the yeast? It not only stated this once but twice in capital letters. Since it has an OG around 1.070, I decided to re-hydrate the yeast regardless of what the instructions told me. The kit came with US-05. I used the US-05 that came with it plus a half of another pack.

I pitched the yeast about 36 hours ago and it is fermenting nicely. Not enough to have to use a blow-off tube but visible action with some bubbling going on in the airlock.
 
Well, that would definitely include me "mostly for beginners". However, I didn't want to chance not having enough active yeast which is I why I decided to go against the directions on that piece.
 
I agree - I think it's to prevent inexperienced brewers from accidentally killing their yeast (by rehydrating it in too-hot water) or contaminating their batch (through poor sanitation during the delicate rehydration procedure).
 
Yeah, I'd say the kit's instructions are written as a way to minimize mistakes so the product's customers will seem happy with said product. Can you ferment just fine without rehydrating? Absolutely? Is there a chance rehydrating will be done incorrectly, thus the beginning brewer will blame the kit? Absolutely. To be fair, in my first few kits I didn't rehydrate and I'm not sure there was a difference. I do now as it's "best practice" but it would be a good experiment - to split a batch between rehydrated and pitched dry yeast and see if there was a difference.
 

Good read, thanks sharing the link. The results of the experiment seem to be fairly consistent with what I've been reading in posts from people on this board. That is, on brews under .0160, you can probably get away without re-hydrating the yeast. However, with higher gravity brews (such as 1.070 like I just brewed), you will probably start seeing a difference.

It would be interesting to do this experiment at 1.060, 1.070 and 1.080 to see if the changes increase as there is an increase in gravity. Perhaps this has been done - if so, I would love to learn about it!
 
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Don't you risk shocking your yeast pitching it around 85-90 degrees if your wort is chilled to about 70 degrees? The instructions that I've been following recommends getting the yeast within 5 degrees of the wort. After looking more at other directions for re-hydrating yeast, I've seen within 10 degrees as well.

85-90*F is the original temp of the water that the packet of yeast is added to, not the temp of the slurry at pitching time .

I should have mentioned that, after giving the yeast the proper amount of time to rehydrate (as per the yeast instructions) I'll "attemperate" the slurry by adding a small amount of the cooled wort (I pitch ales around 60-62*F), stir and wait a few minutes. By the second or third addition of the cooler wort, the slurry is within 10*F of the wort and ready to pitch.
 
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