Pitch dry yeast 5 hours after hydrating

I'm going to brew a simple pale ale tonight and I'm going to try something different. I use US05 and BRY-97 quite a bit and I've had great success with both. The problem I've struggled with is timing the water temp, rehydration time, and getting the yeast attemperated.
Tonight I'm going to rehydrate the yeast during the mash and just let it sit at room until I'm ready to pitch about 5 hours later, which takes care of all those issues.
I've read that it doesn't hurt the yeast to sit around for a while, you just lose the benefit of all the goodness built in to the yeast cells during the drying process.
Just wondering if anybody has tried this and how it turned out?

There is some literature to suggest that you should rehydrate not much more than 30 minutes before pitching. This is because certain energy reserves (glycogen) within the dried yeast are consumed as the yeast rehydrates in water - which is obviously devoid of any source of energy for the yeast.

This probably isn't a hard-and-fast number, and certainly people will disagree with it, but you should aim to incorporate it into your schedule. I know things can be pandemonium on some brewdays but you soon find a rhythm, avoiding the problem won't help with that. A well thought out list always helps !

Their is so much information and misinformation in the world we live in! I don't know for sure but heard your yeast will start dying after about 30 minutes, because they are hungry and don't have anything to eat, I have no idea how long you can actually wait.

I usually let it sit for at least 2 hours. It's not really something I do intentionally because I think it benefits the yeast. I just like to have it ready once the wort is at the correct temperature so it's one of the first things I do.


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Without knowing the technical details and the optimum time to wait, I would be temped to sprinkle into the wort dry, as opposed to waiting 5 hours.

By the way after i rehidrated my dry yeast in 90-100F water, should i wait until it cools down to 65-70F before pitching?

The reason i ask this is strongly related to the thread. I mean sometimes it takes longer than 30 minutes for my rehidrated yeast to cool down to room temp.

I did this on accident once. I hydrated my yeast (BRY-97) then something came up, so I wasn't able to pitch for about 3 or 4 hours. The beer did not turn out great. It attenuated okay, but it took forever to get going, and there was a flaw in the final beer that I couldn't pinpoint...I always attributed it to the yeast sitting out too long. Whether or not that is true, I have no idea. And I wasn't about to try repeating the experiment.

I know, I'm not being super helpful here. But I thought I would pass along my anecdote.

By the way after i rehidrated my dry yeast in 90-100F water, should i wait until it cools down to 65-70F before pitching?

The reason i ask this is strongly related to the thread. I mean sometimes it takes longer than 30 minutes for my rehidrated yeast to cool down to room temp.

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You should be letting your yeast rehydrate for 15-20 minutes anyway. It should be cool enough by then. I'd say just pitch it. BTW, if it's still hot at 30 minutes, you might be using too much water. I rehydrate in a very wide, shallow vessel...more surface contact for the yeast. By the time I pitch, it's cooled to room temp.

The risk of the rehydrated yeast being woken up with not much to eat bothers me, what about rehydrating as instructed, then at about one hour giving it a some weak wort to stop them fading away, then pitch later.

My idea came from reading Clayton Cone's (of Lallemond) response on an old HBD post.

We recommend that the rehydrated yeast be added to the wort within 30
minutes. We have built into each cell a large amount of glycogen and
trehalose that give the yeast a burst of energy to kick off the growth
cycle when it is in the wort. It is quickly used up if the yeast is
rehydrated for more than 30 minutes. There is no damage done here if it is
not immediatly add to the wort. You just do not get the added benefit of
that sudden burst of energy.

Of course the problem is he says it's not a problem if the yeast "is not immediately added to the wort", he doesn't specify how long it would take for it to be a problem....

My last batc the rehydrated yeast sat for around 1.5 hrs. The only thing I have noticed so far is the longer lag time for the yeast to ramp up to good fermentation activity. The yeast did bring the wort to the proper fg. Taste... Well I can not comment yet.

No this ain't right, the purpose of rehydrating is surely to get the yeast in the best condition to be pitched, so it can get going immediately and grow, rather than die.

I only use dry yeast in wine making but it is the same bug so there should not be any difference.

1) Heat water to 110F (not RO or distilled)
2) Mix yeast nutrient into water
3) With water now about 104F, add dried yeast and gently mix
4) After 15-20 minutes (but no more than 30min), begin tempering with small amounts of wort (preferably at ferm temp).
5) Repeat the tempering step until the yeast starter and beer wort are within at least 15F of each other.
6) Pitch rehydrated yeast.

Once you begin tempering you are providing food to the yeast and the 30 minute limit is no longer critical. However, you do not want to let the yeast run out of food or they begin to go back through their dormancy stages or die.

fartinmartin said:

No this ain't right, the purpose of rehydrating is surely to get the yeast in the best condition to be pitched, so it can get going immediately and grow, rather than die.

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Correct. The re hydration step avoids killing yeast via osmotic shock. Whenever the yeast get sprinkled directly into the wort they are unable to control what goes through their cell walls until they are rehydrated. The resulting transfer of compounds into the cells (compounds they are not ready for yet) kills a lot of them. According to Jamil Z it kills about 50% of them. Re hydrating with water allows the cells to be in control and ready to function when you put them into the wort. This keeps many more alive and healthy.

Fermentis says you can wait to pitch, the time varies based on storage temp (read their FAQ here), but the caveat is that you lose the benefit of the boost of energy that was mentioned earlier in the thread. Not the end of the world, but not ideal either.

The_Glue said:

By the way after i rehidrated my dry yeast in 90-100F water, should i wait until it cools down to 65-70F before pitching?

The reason i ask this is strongly related to the thread. I mean sometimes it takes longer than 30 minutes for my rehidrated yeast to cool down to room temp.

Click to expand...

I temper the rehydrated yeast with the cooled wort.

As the wort reaches pitching temp you add the hot water to the yeast. You don't need much. I use a half cup. Wait three min. Then add two cups of cooled wort very slowly over a ten minute period while swirling or mixing the yeast. I like swirling since it allows me to keep things covered. The key if to keep a homogenous temperature that changes slowly. This also gives the yeast food within three to five min of rehydration. Easy!

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I see no reason not to pitch within 15 min of rehydrating. It's very little work.

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