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General Category => Yeast and Fermentation => Topic started by: dimik on October 15, 2012, 01:53:29 PM

Title: Rehydrating Dry Yeast
Post by: dimik on October 15, 2012, 01:53:29 PM
I've always just sprinkled dry yeast into the wort and didn't give it much thought, but started thinking more about it recently. So I tried it with one of my latest brews and I must say the reduced lag time is just amazing. Cut it at least in half. Think I'll keep doing it in the future. Just felt like sharing :)

Here is some more of my thoughts on this topic (http://bkyeast.wordpress.com/2012/10/15/yeast-rehydration/)
Title: Re: Rehydrating Dry Yeast
Post by: hamiltont on October 15, 2012, 02:12:21 PM
I know some very good brewers will say Bah Humbug, just sprinkle it. Obviously it works but I have to wonder if there is just an over abundance of yeast cells in a packet that it doesn't really matter.  I always rehydrate BTW. Good to see you had positive results. Cheers!!!
Title: Re: Rehydrating Dry Yeast
Post by: davidgzach on October 15, 2012, 02:13:43 PM
Yep, you lose about half of your yeast cells by sprinkling versus rehydrating. 

Dave
Title: Re: Rehydrating Dry Yeast
Post by: nateo on October 15, 2012, 02:35:39 PM
You also lose a lot of cells rehydrating at 70* vs 100*.
Title: Re: Rehydrating Dry Yeast
Post by: a10t2 on October 15, 2012, 03:39:38 PM
You also lose a lot of cells rehydrating at 70* vs 100*.

From what I've seen that isn't necessarily true.
Title: Re: Rehydrating Dry Yeast
Post by: nateo on October 15, 2012, 04:48:11 PM
http://koehlerbeer.com/2008/06/07/rehydrating-dry-yeast-with-dr-clayton-cone/

I've noticed dry yeast hydrates and becomes active more quickly if rehydrated at higher temperatures. At 100*+ the yeast gets creamy and bubbly within a few minutes.
Title: Re: Rehydrating Dry Yeast
Post by: tcanova on October 15, 2012, 08:08:12 PM
I always rehydrate because it is always what I have done when making bread.  May not translate to beer yeast but it just kinda made sense to me.
Title: Re: Rehydrating Dry Yeast
Post by: davidgzach on October 15, 2012, 08:16:07 PM
Just finished Chris White and Jamil's book on yeast.  95F-105F is optimal from what I remember. 

Dave 
Title: Re: Rehydrating Dry Yeast
Post by: kramerog on October 15, 2012, 08:25:33 PM
Just finished Chris White and Jamil's book on yeast.  95F-105F is optimal from what I remember. 

Dave

Someone should tell Fermentis!
Title: Re: Rehydrating Dry Yeast
Post by: nateo on October 15, 2012, 08:42:57 PM
Someone should tell Fermentis!

Clayton Cone said that every strain has a unique optimal rehydration temperature. So for Fermentis to say that all of their beer yeasts should be rehydrated between 20-26*C is a most likely a simplification for ease of use, and not the optimal solution. Kinda like how Wyeast insists you don't actually need a starter for most beers.
Title: Re: Rehydrating Dry Yeast
Post by: skrag6713 on October 15, 2012, 09:12:22 PM
i've rehydrated, sprinkled, and made starters with dry yeast.  sprinkling is definitely longer lag than the other 2 from what i've seen.  as for starters vs rehydrating, i don't necessarily think the difference in lag is worth the time and materials put into a starter.
Title: Re: Rehydrating Dry Yeast
Post by: dimik on October 16, 2012, 12:46:29 AM
I'll have to try the temperature range. I just used the data from the study sited that there is no difference in viability.
Title: Re: Rehydrating Dry Yeast
Post by: a10t2 on October 16, 2012, 02:22:18 AM
I'll have to try the temperature range. I just used the data from the study sited that there is no difference in viability.

Just to be clear, I've only used US-05, and I've only used methylene blue to test viability. It could well be that the results aren't applicable to all strains, or that it's simply an artifact of the methylene blue staining.
Title: Re: Rehydrating Dry Yeast
Post by: dimik on October 16, 2012, 02:28:15 AM
That's exactly why I said that methylene blue staining is dubious. In all seriousness I can't think of anything better than trypan blue unless you wanna go with fluorescence. That's why I want to try Neutral and Phenol Reds in a neutralized/alkaline conditions since they would only work if the cell is intact.

Another thing about temperatures that concerns me is that 100 degrees is a lethal temperature for a lot of yeast strains so rehydrating in that is just scary to me. But who knows, maybe it is better.

On another hand I've never seen such a vigorous fermentation with dry yeast so shortly after pitching as I did this time.
Title: Re: Rehydrating Dry Yeast
Post by: kramerog on October 16, 2012, 03:07:14 PM
Regarding the source of water for rehydrating yeast, I used to boil the water first but now I used municipal water that has passed through a carbon monobloc filter reasoning that it was very unlikely to contain significant quantities of beer spoilers.  Is my reasoning correct?  I don't repitch my yeast.
Title: Re: Rehydrating Dry Yeast
Post by: blatz on October 16, 2012, 03:25:55 PM
unopened 1/2 liter bottle of distilled or RO water (should be sanitary so long as it is sealed), let warm in the sun, the dump half, add yeast, swirl, voila.

most of the time, I'm too lazy to do it and just sprinkle and add another pack...
Title: Re: Rehydrating Dry Yeast
Post by: erockrph on October 16, 2012, 03:29:59 PM
unopened 1/2 liter bottle of distilled or RO water (should be sanitary so long as it is sealed), let warm in the sun, the dump half, add yeast, swirl, voila.

most of the time, I'm too lazy to do it and just sprinkle and add another pack...

Interesting. I think I've always heard from the rehydration camp that you shouldn't use RO/distilled water because the yeast want some minerals in their rehydration water.
Title: Re: Rehydrating Dry Yeast
Post by: Kaiser on October 16, 2012, 03:30:19 PM
Regarding the source of water for rehydrating yeast, I used to boil the water first but now I used municipal water that has passed through a carbon monobloc filter reasoning that it was very unlikely to contain significant quantities of beer spoilers.  Is my reasoning correct?  I don't repitch my yeast.

yes, that should be reasonably safe. Even for repitching yeast. You'll pick up more contamination from brewing than from the water.

If you want to test it, tough, you could do this:

take two glass jars, that you boiled to sanitize them, and fill them with some of your brewed and cooled wort. Then add some tap water to one of them and mark it. Cover with a lid or aluminum foil. Don't close he lid tightly. Let this at a warm spot until it starts fermenting. You are basically doing a wort stability test on the water. If the watered sample turns noticeably earlier, you have a contamination in the water and should refrain from adding it to your beer un-boiled.

Kai
Title: Re: Rehydrating Dry Yeast
Post by: blatz on October 16, 2012, 03:31:10 PM
unopened 1/2 liter bottle of distilled or RO water (should be sanitary so long as it is sealed), let warm in the sun, the dump half, add yeast, swirl, voila.

most of the time, I'm too lazy to do it and just sprinkle and add another pack...

Interesting. I think I've always heard from the rehydration camp that you shouldn't use RO/distilled water because the yeast want some minerals in their rehydration water.

that's true.  I've heard that as well.  guess you could use spring water instead - I generally have used whatever we had in the outside fridge - sometimes spring, sometimes distilled/dasani
Title: Re: Rehydrating Dry Yeast
Post by: nateo on October 16, 2012, 03:35:30 PM
I use 10ml per gram tap water in mason jar, microwave for 2-3 minutes, then let cool to 105-110* or so, then add yeast. The cold yeast usually drops the water temp 5* or so. I use go-ferm more often than not, so if you're using something like that, distilled water would be fine. Otherwise, diffusion will suck all the goodies out of the yeast bags.
Title: Re: Rehydrating Dry Yeast
Post by: a10t2 on October 16, 2012, 08:25:13 PM
Regarding the source of water for rehydrating yeast, I used to boil the water first but now I used municipal water that has passed through a carbon monobloc filter reasoning that it was very unlikely to contain significant quantities of beer spoilers.  Is my reasoning correct?  I don't repitch my yeast.

I would use the unfiltered water, personally. The carbon is filter is just another opportunity for contaminants to be introduced.
Title: Re: Rehydrating Dry Yeast
Post by: firedog23 on October 16, 2012, 08:45:17 PM
I just used Fermentis T58 and did not hydrate and quite honestly, I don't know if it would have started any faster or needed to hydrate.  I have had great luck with US-05 but this stuff was a monster.  It raced to full fermentation in 6 hours and the next morning it was around 78 degrees which made me move quick to cool it down as I did not see the big temps coming.  It has since been cooled to the mid-60's but it is still bubbling away.
Title: Re: Rehydrating Dry Yeast
Post by: kramerog on October 16, 2012, 10:05:42 PM
Regarding the source of water for rehydrating yeast, I used to boil the water first but now I used municipal water that has passed through a carbon monobloc filter reasoning that it was very unlikely to contain significant quantities of beer spoilers.  Is my reasoning correct?  I don't repitch my yeast.

I would use the unfiltered water, personally. The carbon is filter is just another opportunity for contaminants to be introduced.

The carbon filter removes chlorine which is a minor plus from avoiding chlorophenolics.  The monobloc also removes bacteria, but I couldn't say down to what size. 
Title: Re: Rehydrating Dry Yeast
Post by: tschmidlin on October 20, 2012, 06:55:40 AM
Another thing about temperatures that concerns me is that 100 degrees is a lethal temperature for a lot of yeast strains so rehydrating in that is just scary to me. But who knows, maybe it is better.
I think it would be fine - I typically rehydrate at 100-105F without issues.  The water doesn't stay that warm for that long.  There are yeast assays that call for 108F for 15 minutes, and the yeast survive that just fine so I doubt 105F and dropping over time is going to cause problems (and it hasn't for me).
Title: Re: Rehydrating Dry Yeast
Post by: dimik on October 22, 2012, 04:39:49 AM
Actually it seems to have worked very well.
It bubbled like MAD at 54 for about 2 days in just a couple hours after pitching (was too busy to look at the temperature so ended up with an English "lager" Winter Warmer lol). After that I moved it to my room and it bubbled for one more day and stopped. Not going to even look at it for a few more weeks, but it seems to me like it was the strongest dry yeast induced fermentation I've ever experienced.
Title: Re: Rehydrating Dry Yeast
Post by: anje on November 06, 2012, 09:18:17 PM
Well, I tried it this time. Rehydrated a pack of US-05 in the Fermentis-recommended 80F water for a while (I know, sounds cool to me too, but I decided to do it their way for a first try), then pitched it. Next morning, the airlock was burbling happily. Usually, I spend the day after brewing anxiety-ridden because I didn't seem much yeast activity before leaving for school.

There's more than one thing changed with this batch vs the previous APA I did, so I don't know what I'll be able to attribute specifically to the rehydrated pitch. (Need to try new things vs need to control experiments -- Argh!) But the peace of mind at seeing such obvious fermentation alone is reason to keep doing it.
Title: Re: Rehydrating Dry Yeast
Post by: Pinski on February 08, 2013, 03:49:14 PM
So, If I'm planning on boiling my water that I'll use to rehydrate some US-05 is there any reason I shouldn't add enough DME to the equivalent concentration of a typical starter  and a pinch of yeast nutrient for the purpose of rehydrating? I'm wondering if this would provide a nice boost or if the yeast would be confused by spending a short time in a "starter" solution prior to being pitched (say, after a couple hours or so).
Title: Re: Rehydrating Dry Yeast
Post by: morticaixavier on February 08, 2013, 04:34:36 PM
So, If I'm planning on boiling my water that I'll use to rehydrate some US-05 is there any reason I shouldn't add enough DME to the equivalent concentration of a typical starter  and a pinch of yeast nutrient for the purpose of rehydrating? I'm wondering if this would provide a nice boost or if the yeast would be confused by spending a short time in a "starter" solution prior to being pitched (say, after a couple hours or so).

As I understand it this is a bad idea because the yeast, when first reintroduced to a liquid environment are not prepared to triage what goes in to the cells via dried out membranes. So they can not regulate how much and and what kind of things are coming in and this causes a lot of damage if there are lots of sugar and other stuff in the liquid. Plain water gives them a chance to wake up and get their membranes working properly before they have to deal with sugars and other chemicals.

They already have the reserves they need to get through this period well. Hence the manufacturers recommending rehydration in plain water.
Title: Re: Rehydrating Dry Yeast
Post by: Pinski on February 08, 2013, 04:48:04 PM
So, If I'm planning on boiling my water that I'll use to rehydrate some US-05 is there any reason I shouldn't add enough DME to the equivalent concentration of a typical starter  and a pinch of yeast nutrient for the purpose of rehydrating? I'm wondering if this would provide a nice boost or if the yeast would be confused by spending a short time in a "starter" solution prior to being pitched (say, after a couple hours or so).

As I understand it this is a bad idea because the yeast, when first reintroduced to a liquid environment are not prepared to triage what goes in to the cells via dried out membranes. So they can not regulate how much and and what kind of things are coming in and this causes a lot of damage if there are lots of sugar and other stuff in the liquid. Plain water gives them a chance to wake up and get their membranes working properly before they have to deal with sugars and other chemicals.

They already have the reserves they need to get through this period well. Hence the manufacturers recommending rehydration in plain water.

That makes really good sense.  I suppose I should have just asked myself what I would prefer if I were dehydrated. Thanks Mort.
Title: Re: Rehydrating Dry Yeast
Post by: BrewQwest on February 12, 2013, 09:42:38 PM
Tried something new, for me anyways.... took some go-ferm rehydration nutrient at the proper dosage and added that to the cooled boiled water...then added the S-189 lager yeast packets to that....waited 15 min....slightly stirred (became really frothy) and pitched it into the fermentor at 50F .... bubbling merrily away within 8 hours.... cheers!!
Title: Re: Rehydrating Dry Yeast
Post by: Pi on February 14, 2013, 04:20:30 PM
when rehydrating dry yeast, using cooled boiled water, the fact that the O2 has been cooked off any concern?
Title: Re: Rehydrating Dry Yeast
Post by: denny on February 14, 2013, 04:36:53 PM
when rehydrating dry yeast, using cooled boiled water, the fact that the O2 has been cooked off any concern?

I don't think so.  You need O2 for cell growth, and when you rehydrate dry yeast you're not going for cell growth.
Title: Re: Rehydrating Dry Yeast
Post by: tom on February 14, 2013, 05:01:18 PM
And it is all set up with lots of sterols.  Dry yeast may need less O2 than liquid.
Title: Re: Rehydrating Dry Yeast
Post by: CASK1 on February 15, 2013, 03:37:19 AM
Here's a nice article on the topic from Northern Brewer:

http://www.northernbrewer.com/connect/2010/06/the-importance-of-being-hydrated/
Title: Re: Rehydrating Dry Yeast
Post by: bazowie on February 18, 2013, 11:03:19 PM
The yeast book I bought from AHA recommends to rehydrate at 105 deg, wait, stir, cool to pitch temp, and pitch.
Title: Re: Rehydrating Dry Yeast
Post by: dimik on March 14, 2013, 02:43:10 AM
Actually I don't think you need oxygen for rehydration for two reasons:
1 - Dry yeast should have whatever they need to get started in the preservative.
2 - Oxygen is actually a very toxic thing. Just because we evolved to use it doesn't mean that it's good for life all the time. So I'd imagine high oxygen concentration in water/wort would result in even more cell death while their membranes are still fragile and not rebuilt. Afterwards, pitching into a well oxygenated wort would be good because it would help in growing and forming stronger membranes, which would prolong and improve their activity and viability.

Here is a little experiment I did to follow up on the original topic
http://bkyeast.wordpress.com/2013/03/13/more-on-yeast-rehydration/
Title: Re: Rehydrating Dry Yeast
Post by: davidgzach on March 14, 2013, 11:28:36 AM
when rehydrating dry yeast, using cooled boiled water, the fact that the O2 has been cooked off any concern?

I don't think so.  You need O2 for cell growth, and when you rehydrate dry yeast you're not going for cell growth.

+1.  Or in it's absence for cell growth, sterols and fatty acids.  Hence the olive oil experiment.