Rehydrating and Pitching Dry Lager Yeasts

[mdennytoo]

Please don't beat me up, I know this looks like a hundred previous posts! But, I have read the hundred and don't see where this basic conundrum is addressed. Some have asked, but the answers are "I just do this and it works. DWHaHB, etc."

We want to pitch a properly re-hydrated dry yeast at or slightly below fermentation temps to avoid the production of fruitiness or diacetyl. Depending on the brand, you rehydrate at 95f-100f or 73°f ± 6°f so you don't kill half your cells. You don't want to let the re-hydrating yeast sit without any sugar for longer than 20 min, 30 min depending on the brand so that you don't kill half your cells.

Here is the rub; you don't want to throw 90f slurry into 50f wort because that will shock the yeast into going dormant.

How do you gently cool your slurry in 10 minutes flat so that you don't go out side of your 30 minute window?

 

[Magic8Ball]

Once the yeast is ready, I will adjust the temperature by using small additions of wort, a little at a time so not to make more than a 5 degree jump.

 

[beersk]

What I do is rehydrate the yeast while I'm brewing in a mason jar. I crash my wort over night in the fermentation fridge along with the mason jar of rehydrated yeast and aerate and pitch in the morning. Works pretty well. I don't think the 20-30 minutes without sugar thing is true.
But generally, I don't worry much about pitching temp. Maybe I should. But with ales, I typically rehydrate during the brew session, then pitch. It's maybe at 80-85F when I pitch with the wort being in the mid 60's probably. Seems to work fine.

 

[BigFloyd]

Once the yeast is ready, I will adjust the temperature by using small additions of wort, a little at a time so not to make more than a 5 degree jump.

This ^^^^^^ is the recommended way to do it. I like to give a few minutes between wort additions. It normally takes me 3 wort additions to get the slurry to within 10*F of an ale wort. I've only ever used liquid yeast on lagers (with big starters).

 

[boydster]

Once the yeast is ready, I will adjust the temperature by using small additions of wort, a little at a time so not to make more than a 5 degree jump.

+1 to this. This method makes for happy, healthy yeasties. Make them happy, they will reward you with delicious beer. Don't put them in the fridge after rehydrating and sacrifice their happiness.

 

[beersk]

+1 to this. This method makes for happy, healthy yeasties. Make them happy, they will reward you with delicious beer. Don't put them in the fridge after rehydrating and sacrifice their happiness.

You think it's any different than cold crashing a starter? Seems the same to me.

 

[boydster]

You think it's any different than cold crashing a starter? Seems the same to me.

Yes. The starter has nutrients in it that the yeast can consume even as they are cooling and dropping out. When you rehydrate, the yeast consume the packaged nutrients and quickly run out of food. They are effectively starving (thus, more stressed, lower viability & vitality) by the time they finally hit the wort.

 

[mdennytoo]

Ready to go. I will save back several ounces of 50f wort to drop the temp slowly.
Another question: is Saflager W 34/70 supposed to be rehydrated at about 100f like every other brand? Their .pdf on their website says 73f. Easier to attemporate. I will do 73f, but why would Fermentis be different? The lingo they use is generally not like our homebrew vocab. Ex.: they don't use terms like attenuation. In stead they show a fast ferment test of 11g/l of residual sugars? Probably a better way to say it.

 

[bethebrew]

Ready to go. I will save back several ounces of 50f wort to drop the temp slowly.
Another question: is Saflager W 34/70 supposed to be rehydrated at about 100f like every other brand? Their .pdf on their website says 73f. Easier to attemporate. I will do 73f, but why would Fermentis be different? The lingo they use is generally not like our homebrew vocab. Ex.: they don't use terms like attenuation. In stead they show a fast ferment test of 11g/l of residual sugars? Probably a better way to say it.

Are you hung up on yeast rehydration and truly of the (mistaken) belief that 50% of yeast magically perish if dry yeast is sprinkled into wort? Now it goes further yet, and you must hold back 50 F wort and gently cool the now 100 F liquid yeast back down.

I just don't get it. Dry is so easy.

 

[boydster]

Are you hung up on yeast rehydration and truly of the (mistaken) belief that 50% of yeast magically perish if dry yeast is sprinkled into wort? Now it goes further yet, and you must hold back 50 F wort and gently cool the now 100 F liquid yeast back down.

I just don't get it. Dry is so easy.

You are wrong. This has been discussed a lot. Read Yeast by Chris & Jamil or see other studies by other sources if you like. You DO risk killing up to 50% of the yeast by skipping the rehydration step. You also reduce vitality & viability by rehydrating in cooler water.

 

[Wynne-R]

You don't want to let the re-hydrating yeast sit without any sugar for longer than 20 min, 30 min depending on the brand so that you don't kill half your cells.

I hadn’t heard that. I usually go an hour or more. I set the flask in the same water tub as the fermentor and wait for the temps to equalize. It makes sense that you want to pitch before the nutrients are too depleted, but 20-30 minutes seems fussy.

I realize ‘It seems I can get away with it’ is not the same as best practice, maybe I’m doing it wrong. Do you have any evidence to support this short timetable?

 

[boydster]

Ready to go. I will save back several ounces of 50f wort to drop the temp slowly.
Another question: is Saflager W 34/70 supposed to be rehydrated at about 100f like every other brand? Their .pdf on their website says 73f. Easier to attemporate. I will do 73f, but why would Fermentis be different? The lingo they use is generally not like our homebrew vocab. Ex.: they don't use terms like attenuation. In stead they show a fast ferment test of 11g/l of residual sugars? Probably a better way to say it.

I haven't done cell counts at 73° vs 100°, so I can't tell you for sure, but manufacturer directions for ideal temp should be trusted. I suspect the 100° water would be just fine, possibly better, but that is pure speculation.

 

[mdennytoo]

Not that a picture is necessary for this thread, but I just couldn't help myself. Ain't it purdy! 5 gals. of 1.054 ~ish Marzen berwed in October like a goofball. I had some foam still on the yeast at 61f and pitched into 50 deg wort at 48f. So its probably good. Thanks y'all.

 

[mdennytoo]

Here is another. Throwing sulfur and foaming a bit. Seems to be going fine.

 

[beersk]

I hadn’t heard that. I usually go an hour or more. I set the flask in the same water tub as the fermentor and wait for the temps to equalize. It makes sense that you want to pitch before the nutrients are too depleted, but 20-30 minutes seems fussy.

I realize ‘It seems I can get away with it’ is not the same as best practice, maybe I’m doing it wrong. Do you have any evidence to support this short timetable?

I just don't believe this. But maybe I'll try it next time.

 

[beersk]

Here is another. Throwing sulfur and foaming a bit. Seems to be going fine.

That looks good. It's about what my lager fermentations look like. Aerating with pure O2 makes a big difference, I think.

 

[boydster]

I hadn’t heard that. I usually go an hour or more. I set the flask in the same water tub as the fermentor and wait for the temps to equalize. It makes sense that you want to pitch before the nutrients are too depleted, but 20-30 minutes seems fussy.

I realize ‘It seems I can get away with it’ is not the same as best practice, maybe I’m doing it wrong. Do you have any evidence to support this short timetable?

According to Yeast, you want to get the yeast down to pitching temp and pitch it as soon as possible after rehydration is complete.
Pg 148, discussing proper use of dry yeast:

Once the yeast is ready, add it to the wort as soon as possible. At warm temperatures, the yeast cells quickly use up their energy reserves.

While that is a rather generic statement with no specific mention of what sort of window you have before yeast health degrades, another HBT member emailed Danstar to ask them specifically what the timeframe is:

I emailed Danstar about yeast timing. The answer was: “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.” I avoid having a delay by having the rehydration complete 10 – 15 minutes after the wort is ready for it.

I agree that it's probably fine, but I feel like the better you treat your yeast, the better it will treat you.

Edit: Fermentis also recommends a 30-minute rehydration. See http://www.brewwithfermentis.com/tips-tricks/yeast-rehydration/

Granted, they don't discuss how quickly yeast health drops off outside that time frame, but obviously the yeast need to eat so they don't starve and they have very little to sustain them in those little packets.

Edit again: Found the other resource I was looking for. Yooper posted this a while back. http://home.comcast.net/~mzapx1/FAQ/Rehydrate.pdf
Again, it reiterates the 30 minute time frame.

 

[Wynne-R]

Awesome! Thanks boydster.

It’s nice to have actual facts from card-carrying experts.

 

[mdennytoo]

Here it is at ~1.011 after 2 day 'D' rest. Racking to secondary and slowly dropping the temp from today. This worked out well. It tastes ready now except for carbonation. I probably won't be able to wait but two more weeks.

 

[mdennytoo]

From above: "Fermentis also recommends a 30-minute rehydration. See http://www.brewwithfermentis.com/tips-tricks/yeast-rehydration/

Granted, they don't discuss how quickly yeast health drops off outside that time frame, but obviously the yeast need to eat so they don't starve and they have very little to sustain them in those little packets."


This is what got me a little wound up. I thought that crashing the yeast from 77f down to 48f in 20 minutes would just put them to sleep. Rehydrating them in 48f water would be so much more convenient, but they die, apparently.

 

[boydster]

OK time for me to eat my humble pie. I was just reading over a Fermentis "Tips and Tricks" pamphlet that they link to on their website and it says that after you have done the initial 30-minute rehydration procedure, you should pitch the yeast within 4 hours if stored at 25C, 6 hours at 20C, and 18 hours at 4C. This is certainly good info for anyone that is unable to pitch immediately.

They have it hosted on a different site, so here is both the link to Fermentis' page (so you don't have to trust a sketchy looking link from me) and the link to the actual place where the PDF is:

http://www.fermentis.com/brewing/craftbrewing/tips-tricks/
http://en.calameo.com/read/0026934555f07e32293ea

 

[TrickyDick]

I need of a quick answer here, as I'm preparing to depart for the LHBS.

The real quick question is: how many cells per sachet for the Saflager 23? The remainder of the message is my typical rambling...

Planning to go buy some fresh yeast - ruined my first real yeast washing experience by collecting mostly trub in my one gallon jar. only about a 1/2 inch layer up top of suspended yeast - the rest is THICK sludge. Ditto on two additional 1 quart jars I collected from conical. Yeastcalc.co says I need 1629 billion cells for my 11 gallon batch of 1.081 lager. Seems I need to go buy some dry yeast for this IPL I'm planning.

How many packs of yeast (Planning on using saflager23 if they have enough in stock at LHBS) will I need? I've heard that the packs of S04/S05 contain 200 billion cells.

Fermentis website doesn't say, only > 6x10^9 / g at packaging. A little math tells me that's 6 billion cells per gram, and in 11.5 gram sachets, that's a far cry from 200 billion cells. The greater than sign isn't very helpful.

Was planning to do staged oxygenation, with a second blast at the 12 hour mark. Cold pitch? I've not had great success with the cold pitch in the past with sluggish fermentation. Probably pitch at 58º and then chill hold for 12 hours, perform second oxygen addition, and then set temp controller to 51º.

I'll follow the rigorous re-hydration methods. Worried that with an estimate 8-9 packs of yeast that its going to dilute the wort!! How can I account for that? Its going to be nearly 1 liter of water. Maybe I should RDWAHAHB on that part.


Thanks

TD

 

[trentm]

I need of a quick answer here, as I'm preparing to depart for the LHBS.

The real quick question is: how many cells per sachet for the Saflager 23? The remainder of the message is my typical rambling...


Fermentis website doesn't say, only > 6x10^9 / g at packaging. A little math tells me that's 6 billion cells per gram, and in 11.5 gram sachets, that's a far cry from 200 billion cells. The greater than sign isn't very helpful. TD

If they count the way Danstar counts here is the confusion (this is clipped from the Danstar website)

"The viabilities mentioned on the technical data sheets are minimum viable cells per gram that we guarantee determined by plate count on YPD-agar. Usually the viability is higher. There is a slight difference in how resistant the different strains are to drying and rehydration. Usually ale yeast strains are more resistant than lager yeast strains.
You might also consider that you will find much higher cell numbers under the microscope than by plate count, even if you have 100 % viability because you do not always have a single cell forming a colony but rather two or more cells. For Nottingham yeast the average cell count under the microscope is around 20 to 30 billion cells per gram dry yeast."

I think most dry yeast users who have thought this through have decided to go with the 20-30 billion cells per gram. Which would be >200 billion cells per 11 gram pack. After all microscopic cell counts is what the brewing industry relies on for pitching rates.

Here is a link to the article I clipped: http://www.danstaryeast.com/articles/cell-count-and-glycogen

 

[TrickyDick]

I got 9 packs. Tomorrow is brew day.
Peeved that I didn't inspect ALL 9 packs for the date, because there are a couple that are old....
Well, I hope they work for me with proper hydration oxygenation and plenty of time should be enough.

TD