The Importance of Rehydrating Yeast

[Intheswamp]

I was reading through some of the faqs on Lalvin's website and stumbled upon a statement I thought was interesting. I have read where some folks use distilled water and some use deionized water. Personally, I use bottled "spring water". The bolding of part of the print is my emphasis. This is just a part of this particular short faq.

http://www.lalvinyeast.com/importance_rehydration.asp

Rehydration in distilled or deionized water is lethal to the yeast. The cell walls require the presence of some minerals, sodium, calcium, magnesium and or potassium, during rehydration. Tap water at 250 ppm hardness is optimum. Most tap water has enough hardness to do the job. The presence of 1/2% yeast extract, yeast hulls, autolyzed yeast or peptone in the rehydration water will give the yeast an added boost that will get it through its lag phase quicker. After the yeast cell wall has been reconstituted, the yeast returns to its normal ability to be selective

Anyhow, just thought I'd share this info with the other newbees...use it for what it's worth to you.
Ed

 

[Golddiggie]

Many use yeast energizer when rehydrating their yeast. This provides nutrients, and other goodies, for the yeast so that they're better prepared to be poured into the must.

 

[YogiBearMead726]

Many use yeast energizer when rehydrating their yeast. This provides nutrients, and other goodies, for the yeast so that they're better prepared to be poured into the must.

In the very FAQs link provided, there is a disclaimer about Fermaid K (yeast energizer/nutrient) that reads "DO NOT use Fermaid K to rehydrate yeast". The DAP is actually toxic to the yeast during the fragile rehydration stage. Proper rehydration requires Go-Ferm or another rehydration blend. As an aside, sugar is also lethal to yeast during their initial rehydration.

Another key to proper rehydration is to use water @ 104F. Using water at room temp can cause up to 60% of the yeast to die.

The most common cause for stuck or sluggish fermentations is improper rehydration practices...at least according to the yeast experts over at Lallemand/Lalvin. And personally, I've noticed markedly better fermentations when I do rehydrate properly as opposed to before I knew what I was doing.

 

[Golddiggie]

In the very FAQs link provided, there is a disclaimer about Fermaid K (yeast energizer/nutrient) that reads "DO NOT use Fermaid K to rehydrate yeast". The DAP is actually toxic to the yeast during the fragile rehydration stage. Proper rehydration requires Go-Ferm or another rehydration blend. As an aside, sugar is also lethal to yeast during their initial rehydration.

Another key to proper rehydration is to use water @ 104F. Using water at room temp can cause up to 60% of the yeast to die.

The most common cause for stuck or sluggish fermentations is improper rehydration practices...at least according to the yeast experts over at Lallemand/Lalvin. And personally, I've noticed markedly better fermentations when I do rehydrate properly as opposed to before I knew what I was doing.

I, normally, just heat up water in the tea kettle to the right point (reading the package). I use water that went through my filter system, which leaves trace elements/minerals (removes the nasty stuff) in the water. I'm not buying distilled, or RO, water and not about to get the hardware to do either.

 

[veritas]

Personally I swear by Go-Ferm and I also am a huge fan of mass bio pitches.

 

[Medsen Fey]

... As an aside, sugar is also lethal to yeast during their initial rehydration.

I wholeheartedly agree with your post except for the part about the sugar. There have been studies done showing rehydration with a little sugar (I think it was around 50 g/L but don't quote me) can produce better results.

Interestingly some manufacturers, like Vintner's Harvest recommend dry pitching into the must. I contacted them to ask and they said their data showed superior results dry pitching. I asked them to show me any data that indicates this and I received nothing. So I'm not accepting their claim until I see some evidence.

 

[skunkboy]

I've been know to toss a little bit of apple juice into rehydrated yeast before tossing it into the must... does seem to speed up the little dudes...

 

[Intheswamp]

Newbee opinion here... From what I've gathered from "here and there" the yeast need a short hydration period in which there cell walls are prepared for the work they will be doing. I've heard folks mention about the yeast having "too much pressure" on them in a high gravity must situation. I'm thinking that that might could easily happen to yeast that are in the rehydration stage of their life if too much sugar is available. Very shortly after that hydration period they need nutrtiion to be available, though. When I rehydrated my yeast (only done it one time so far so ya'll *know* I'm a real pro! ) I added some must at intervals after mixing the yeast with the Go-Ferm Protect slurry...that must had plenty of sugar and the other things honey has in it...minerals, enzymes, chemicals, etc.,. The yeast had a good fermentation going the next morning and I believe it was a good overall fermentation.

I think I will continue doing what I did this time as I think the yeast may need that short "unpressured" rehydration time but then quickly need nourishment afterward so there's no hesitation in their production of more yeast.

They ya'll for the (as usual) great feedback!

Ed

 

[wildoates]

I, uh...put some water from the tap into a Pyrex measuring cup, add gro-ferm, and put it in the microwave. When it's cool enough I add the yeast. Wait 15 minutes. Pitch into a must also filled with tap water. So far, so good.

 

[YogiBearMead726]

I wholeheartedly agree with your post except for the part about the sugar. There have been studies done showing rehydration with a little sugar (I think it was around 50 g/L but don't quote me) can produce better results.

Interestingly some manufacturers, like Vintner's Harvest recommend dry pitching into the must. I contacted them to ask and they said their data showed superior results dry pitching. I asked them to show me any data that indicates this and I received nothing. So I'm not accepting their claim until I see some evidence.

Very interesting. I always add some must after the initial 10 minutes at 104F with Go-Ferm, because by then the yeast is frothing and I feel like they can handle the sugar. I'll have to try adding a dash of must to the water I use to rehydrate with my next batch.

 

[Chevette Girl]

I used to dry-pitch Lalvin yeasts because my wine kit said to do so. I'm not sure how much of an effect it's had on my wines and meads, I still get the occasional sluggish ferment even now when I rehydrate or make a starter. But in the interest of giving the yeasties the best chance I can, I fill my plastic measuring cup to at least 1 cup with hot tap water, stick in the thermometer, adjust as required with either more hot or cold water to get the right temperature range, pour out all but 1/4 cup, add yeast, set timer, and at the end of the 15 minutes, I either add the yeast to the must or add some must to the yeast. (yeah, the fill it then empty it part sounds stupid but I can't get a reading with my big clunky thermometer with the water level at only 1/4 cup and wasting a cup of water is less wasteful to me than buying a new thermometer when I have one already).