Rehydrating yeast

[The-Engineer-That-Brews]

Blimey, this re-hydrating yeast business is more complicated than I thought. The Lallamand BRY-97 instructions say:

" Rehydration guidelines are quite simple and present a much lower risk of contamination than a starter, which is unnecessary when using the recommended pitch rate of dried active yeast.​

​

Sprinkle the yeast on the surface of 10 times its weight in clean, sterilized water at 30-35°C (86-95F). Do not use wort, or distilled or reverse osmosis water, as loss in viability may result. Stir gently, leave undisturbed for 15 minutes, then stir to suspend yeast completely. Leave it to rest for 5 more minutes at 30-35°C.​

​

Without delay, adjust the temperature to that of the wort by mixing aliquots of wort with the rehydrated yeast. Wort should be added in 5 minute intervals and taking care not to lower the temperature by more than 10°C at a time. Temperature shock of >10°C will cause formation of petite mutants leading to extended or incomplete fermentation and possible formation of undesir- able flavors. Do not allow attemperation to be carried out by natural heat loss. This will take too long and could result in loss of viability or vitality. "​

And there was me just about to sprinkle it on the surface of the wort...

As to what a petite mutant or an aliquot is....

 

[The-Engineer-That-Brews]

So what kind of sterilised water did they have in mind, I wonder, that's that much different to RO ??? Well this lot is getting cooled filtered water from the kettle and it can like it or lump it. Let's just hope the Petite Mutants don't come and get me eh?

 

[marshbrewer]

Wasn't Marx always moaning about the Petite Mutants?

 

[An Ankoù]

Use about 100 ml of boiled and cooled tap water at around 30-35C. By the time to 15+5 minutes has passed, It'll have cooled a bit more anyway. If you're pitching at 20-22 ish, you can just chuck it in as the temperature difference will be less than 10C. If you're doing lager, first you rehydrate at a slightly lower temperature, around 25C and then, after the 15+5 minutes, add enough of your cooled wort to effect a temperature drop of about 5C, leave 5 minutes and add another aliquot until you're within 7 or 8 degrees of the temperature of the wort. Then chuck it in. Petite mutants are mutations of the yeast which behave differently to the parent yeast. If they become dominant then your fermentation won't necessarily go as predicted.
Too much to worry about. If you're making ale, just rehydrate your yeast and chuck it in.

Apparently yeast rehydrates best in hard-ish water.

 

[The-Engineer-That-Brews]

… add another aliquot until you're within 7 or 8 degrees

I went to my local deli but they were fresh out of Aliquots… they suggested a Kumquat might work?

 

[dad_of_jon]

So what kind of sterilised water did they have in mind, I wonder, that's that much different to RO ??? Well this lot is getting cooled filtered water from the kettle and it can like it or lump it. Let's just hope the Petite Mutants don't come and get me eh?

View attachment 51408

boiled water cooled down to the temp recommended using the kettle method

 

[dad_of_jon]

Use about 100 ml of boiled and cooled tap water at around 30-35C. By the time to 15+5 minutes has passed, It'll have cooled a bit more anyway. If you're pitching at 20-22 ish, you can just chuck it in as the temperature difference will be less than 10C. If you're doing lager, first you rehydrate at a slightly lower temperature, around 25C and then, after the 15+5 minutes, add enough of your cooled wort to effect a temperature drop of about 5C, leave 5 minutes and add another aliquot until you're within 7 or 8 degrees of the temperature of the wort. Then chuck it in. Petite mutants are mutations of the yeast which behave differently to the parent yeast. If they become dominant then your fermentation won't necessarily go as predicted.
Too much to worry about. If you're making ale, just rehydrate your yeast and chuck it in.

Apparently yeast rehydrates best in hard-ish water.

I use chase spring. Our tap water is softer than a babys bum. Given our babies are now 20+ I'm not going to ask them to assess the softness of their derriere. because they are no longer babies.

P.S. of course tap water would be chorinated in some way so I wouldn't recommend using that anyway

 

[Tommo 2]

Once the water is boiled not much chance of any chlorine being in it anyway ; and the whole process of rehydration is much easier than it sounds ; have done it for donkeys years with no problem at all and with great results

 

[scomet]

Good yeast management is worth the effort, can make a good beer great!

 

[The-Engineer-That-Brews]

Once the water is boiled not much chance of any chlorine being in it anyway ; and the whole process of rehydration is much easier than it sounds ; have done it for donkeys years with no problem at all and with great results

I agree - it was actually pretty easy. It was just a surprise to me, as the very few times I used dried yeast before (S-04) the packet simply said ‘sprinkle on surface of wort’ :-)

 

[Tommo 2]

Amazes me how many just do the easier thing in brewing like just sprinkle dry yeast on the wort ; which kills so many cells when rehydration gets you so much more viable cells ready to go, is easy to do, produces a much better beer and doesn’t cost anything but a bit of extra time and effort, surly it’s worth it , brewing is about enjoying the hobby , making the best beer you possibly can and enjoying the end product , at least it is for me and I really do enjoy all of the process even bottling like I say not having a dig at anyone each to there own, but if you are a sprinkler I would deffo give it a try , you will get much better results

 

[obscure]

Amazes me how many just do the easier thing in brewing like just sprinkle dry yeast on the wort ; which kills so many cells when rehydration gets you so much more viable cells ready to go, is easy to do, produces a much better beer and doesn’t cost anything but a bit of extra time and effort, surly it’s worth it , brewing is about enjoying the hobby , making the best beer you possibly can and enjoying the end product , at least it is for me and I really do enjoy all of the process even bottling like I say not having a dig at anyone each to there own, but if you are a sprinkler I would deffo give it a try , you will get much better results

As someone who mostly does just that (sprinkles it in directly) I suspect the answer is because I can get away with it. I tend to do 9-11L batches and my OG rarely exceeds 1.050 and even that is on the high side, sure I might loose half my yeast cells but I’m still pitching more than enough. I appreciate that if I was say doing a 23L batch of imperial stout at 1.090 this would be a bad idea but for my lower gravity beers I see it as a case of it works and I’m happy with the results so will keep on being lazy.

I should add that on the rare occasions that I do make stronger beers (Belgium Trippel, Barley Wine etc,) I have started to rehydrate my yeast or make a starter as appropriate as with these I find you really do need to give the yeast all the help you can.

 

[trueblue]

Good yeast management is worth the effort, can make a good beer great!

Could not agree more. Yeast is by far the most important ingredient we use yet a lot of brews put as little effort as they can into making sure the wort they have spent 4 hours producing receives the best yeast in top condition. Can be the difference between good and great beers.

 

[chrisbjones202]

I use a 250ml erlenmeyer flask, star san then pour in 100ml boiling water. Leave to cool to 35 while im doing other things. Easy to swirl the yeast in and again get into suspension before tipping in. No bother at all compared to the rest of the process.

 

[johncrobinson]

I advocate that looking after your yeast is a good thing,I am a winemaker and as such our starting gravities are generally so much higher.

Good treatment of the yeast will always pay dividends.

 

[The Baron]

Interesting I have just watched the latest Geterbrewed youtube video on yeast and they have done trials with Lallemand and have come to the conclusion there is not benefit from creating a starter or dehydrating compared to just sprinkling.
Watch it and see what you think

 

[The-Engineer-That-Brews]

The video mentioned by @the baron :

 

[The-Engineer-That-Brews]

So far I haven't been able to find the 'Lallemand research' referenced by GEB near the beginning of the video; however the following short report of lab testing on S-05 for 'rehydrate vs. sprinkle' is quite interesting: DryYeastViabilityTest

These tests found that proper rehydration did result in slightly less yeast mortality, but that the difference was only 5% not 50% as is commonly claimed.

The author concluded that in a home-brew context the difference was not worth bothering about.

<quote>

Conclusion​

Non-hydrated, direct pitched wort did indeed have a higher death rate than both the hydrated samples.​

However, the loss was minimal in comparison to other sources reporting cell loss rates upwards of 50%.​

The loss is significant enough, particularly when scaling to commercial sized batches that the slightly​

higher loss should be accounted for depending on your desired pitch rate. For typical five or ten gallon​

batches, homebrewers should not have concerns, specifically pertaining to cell counts, as the difference​

in loss between the two methods was only five percent. Now that I have a baseline for comparison, I will​

conclude further testing using these methods on other dry yeast packs to see if the results change.​

Additionally, by my understanding of the date code, the yeast packet that was used is nearly nine​

months old, yet cell death was only 3% on the hydrated sample.​

</quote>

Whether there are other factors related to the health of the surviving yeast is a different question of course...

 

[The Baron]

There is another youtube video
Pitching best practices for Lallemand Dry Brewing Yeast
Sorry I can not do a link as my computer locks at every copy Paste attempt

 

[MmmBeer]

I first came across the 'rehydration concept' whilst doing the IBD general certificate. The text said that the osmotic shock of adding dried yeast direct into wort containing high amounts of sugar would stress the yeast cells, killing many. It recommended using a mixture of cold sterile water (bottled) and boiling water or small amount of wort.

I have done this regularly for the last two years with decent success, however I have inevitably forgotten a few times and pitched direct into the fv with no obvious issues. I have also noticed that it is done in some breweries, but not in others.

My conclusion is that rehydrating is best practice, but not essential.