Rehydrating.....hurrah

[Bribie G]

As mentioned on many threads, the basic underpinning argument is that if you rehydrate yeast cells in wort a fair few of them will die due to osmosis and cell walls rupturing and I'd guess the degree of damage depends on the gravity of the wort. I've also had good results just sprinkling.. of course you are going to get a fermentation and for many Woolies kit users the instruction under the lid is to sprinkle as, for many, once you mention something four syllable like re-hyd-ra-tion their eyes are going to glaze over immediately.

Rehydrating in warm water wakes the bubs all up gently. Dried yeast is different to liquid yeast in that the cells are pre-primed with lipids etc, as a result of the special manufacturing process, and are ready to rock, whilst liquid yeasts need to go through the lag phase and kick in a bit later.

Nearly everything I know about yeast comes from the "Yeast" book, as well as a fantastic lecture at the Brisbane Brewing conference in 2011 by Whitelabs 2.I.C.

 

[DJ_L3ThAL]

I've rehydrated and had good results, I have been wondering what pitching the warmer rehydrated yeast cream (haven't measured the actual temp but I assume it would be around 25-30C by the time I pitched it) into wort at around 20C which would be the ferment temp would do in terms of shocking it? Or are the preprimed lipids of dry yeast what assist against the temp shock?

 

[kaiserben]

By the sounds of this, your beer is totally ruined. Throw everything out and start from scratch as there is no possible hope of making his beer from this horrible, failed rehydration.

I'm a stickler for following the rules and the advice of scientists (the 15min, 1:10, stirring, water that's not cold, using tap water wit minerals rather than distilled) but that's just who I am - we're getting into some serious anecdotal territory here. I do trust the guys who make our dried yeast and follow their instructions but I'm not sure that stirring/not stirring or 15min/5min will give your beer another 5 points in a comp or make your beer slightly more delicious.

Ha! Easy now! I just want to know why my rehydrated yeast didn't go creamy, and if non-creaminess means my efforts were wasted, and if I've missed something obvious.

As it is, my air-lock activity seems to have taken about the same length of time as it would have if I'd just sprinkled.

 

[kaiserben]

I've rehydrated and had good results, I have been wondering what pitching the warmer rehydrated yeast cream (haven't measured the actual temp but I assume it would be around 25-30C by the time I pitched it) into wort at around 20C which would be the ferment temp would do in terms of shocking it? Or are the preprimed lipids of dry yeast what assist against the temp shock?

I'm clearly no expert, but from what I've read you can attemperate your starter by either adding small amounts of water at wort temp, or even small amounts of wort. A youtube vid I watched said if it's within 15F of the wort temp then you won't have to worry. (so what's that? Less than 9.5C difference is okay).

 

[fraser_john]

I found this as well until I started using warmer water to rehydrate. All the texts I found said to use water between 35-40C but I wouldn't believe it as I thought that was way to high. I finally tried after having the same issue you have had and sure enough it worked like a charm.

Yeast taking off and lively in 37C water for 30mins and kick on in the wort in no time.

The attached spreadsheet was gleaned from each product info sheet from each manufacturer, it shows the brand, the yeast strain, recommended rehydration temperature, a +/- value around that temp eg. 25c +/- 3c

View attachment Rehydration Temperatures.xlsx

 

[kaiserben]

Could someone tell me-

If, when sprinkling my M44, it usually takes ~36 hours to see air lock activity, how might I expect that time to change when (successfully) rehydrating?

 

[The Holy Ale]

The attached spreadsheet was gleaned from each product info sheet from each manufacturer, it shows the brand, the yeast strain, recommended rehydration temperature, a +/- value around that temp eg. 25c +/- 3c

Rehydration Temperatures.xlsx

That's a handy spreadsheet. I did find when I rehydrated US05 around the 27C mark the yeast seemed to sink and showed little activity such as forming a "cream" etc.

My 35-40C numbers came from "How to Brew" and other articles online. All recommended higher temps than the manufactures.

I'll definitely be looking into it further and might check out the Yeast book Bribe G recommends

 

[Croc_TFNQ]

I am a total novice to home brewing my first brew was a pimped GB and I knew absolutely nothing.

Just put my second GB in the FV, and, this time I had read and received tons of good advice from many on this great Brewing site, and I rehydrated my yeast just in warm water no wort after a fair bit of research, finally sealed off the FV last night around 1930hrs this morning at 0700hrs it was going like a steam train constant bubbling in the airlock and I mean constant no break at all and does not look like slowing if anything it has increaed through the day.

I am a happy brewer so far :chug:

 

[The Holy Ale]

That's awesome. Nothing beats trying something new and getting good results. Happy brewing

 

[Bribie G]

Could someone tell me-

If, when sprinkling my M44, it usually takes ~36 hours to see air lock activity, how might I expect that time to change when (successfully) rehydrating?

No doubt for the better.

 

[fraser_john]

That's a handy spreadsheet. I did find when I rehydrated US05 around the 27C mark the yeast seemed to sink and showed little activity such as forming a "cream" etc.

My 35-40C numbers came from "How to Brew" and other articles online. All recommended higher temps than the manufactures.

I'll definitely be looking into it further and might check out the Yeast book Bribe G recommends

If the Yeast book is a must for brewers really interested in making sure they understand the fermentation process and how yeast works. A great read.

 

[kaiserben]

Is the Yeast book the one by Jamil & Chris White? ie Yeast: The Practical Guide to Beer Fermentation

 

[DJ_L3ThAL]

Yep!

 

[Bradgc]

I've also started hydrating yeast, I pour boiling water over 1 tsp sugar and cover till warm, then add the yeast. It usually takes about 24+ hours to get activity out of dry yeast in my wort, as opposed to 12 hours when using hydrated yeast

 

[manticle]

No need for sugar. Follow manufacturer's instructions (differ slightly between brands).

 

[danestead]

I rehydrate yeast (and have only every rehydrated yeast, unless u count half a dozen brews when I was 18) for the only reason of getting a more accurate pitch amount. Rehydrating gives apparently almost 100% survival rate where pitching dry gives a pretty vague 50% survival rate. Pitching as accurate an amount of yeast every time gives me consistency so I can focus on other variables.

 

[Gelding]

Rehydrating gives apparently almost 100% survival rate where pitching dry gives a pretty vague 50% survival rate.

Is this referenced from the "yeast" book ?

 

[Rocker1986]

I rehydrate dry yeast too. I noticed the fermentations start to kick off quicker and be a bit more vigorous than sprinkling it dry, once I started doing it. Nowadays I throw it into a starter after rehydrating, not necessary I know, but I do it in order to harvest yeast from the starter. Not saying everybody should start doing that, but it's been working well for me so far.

 

[danestead]

Is this referenced from the "yeast" book ?

No idea but I've read both the yeast book and how to brew and listened to about 100 podcasts by John palmer, Zamil and brad Smith. Usually I try to remember the stuff from credible sources and take the heresay with a grain of salt. So sorry, I don't know which exact source.

 

[Blind Dog]

Is this referenced from the "yeast" book ?

Yes - section heading is 'working with dried yeast' (no idea of page number as it's the kindle version). you apparently get the same 'kill rate' if you rehydrate with room temp water.

Personally, using that book and other sources, I rehydrate at circa 35C in a sanitised zip lock bag using 10ml water per g of yeast, and sit that in a small pot of 35C water and let it come down to close to pitching temp - checked by measuring the water bath temp