Safale S-05 Rehydration question

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daveyohill

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I understand that dry yeast viability is improved with rehydration prior to pitching (according to Jamil anyway).

To re-hydrate I boil 1 cup of water to sterilize and then cool off tin foil covered in a pyrex measuring cup. When the water is below 80degF. I sprinkle the yeast into the water to rehydrate.

The last two times I've done this with S-05 the yeast formed a barrier at surface and even after letting it sit for 1/2hr a major portion of the yeast required stirring to incorporate into the water. It was clumpy and needed stirring to produce a slurry.

When I've done this with S-04 the yeast immediately falls into solution and produces a foamy slurry without stirring within 15 minutes.

Is this a common experience with this yeast?

Do you even bother rehydrating with this yeast.

After 12 hours in primary the airlock has started bubbling every 15-20 seconds so I'm guessing everything is OK. My last beer was fermenting vigorously after 24 hours. I just wonder if I really need to sweat this detail to produce great beer.
 
I understand that dry yeast viability is improved with rehydration prior to pitching (according to Jamil anyway).

This is true and here's why...

When yeast ferment certain sugars (such as maltose), they must first secrete an enzyme that breaks this sugar down so they can metabolize it. They only have the capacity to secrete these types of enzymes when they are healthy and hydrated. Under these circumstances, the yeast's cell membrane won't allow maltose in unchecked.

When a dehydrated yeast cell first becomes hydrated, it allows too many things in the hydration solution into the cell unchecked. When it allows things in that it would normally break down first (e.g., maltose), it can die. This is why it's best to rehydrate in water first. It gives the most viability and cell count.

That being said, it's not black and white and plenty of yeast survive when rehydrated directly in wort. In the case of ales, it is often desired to have a flavor profile that comes from yeast characteristics (esters, etc.). Many of these compounds are produced during the growth phase. So, having a higher cell count, such as that which comes from rehydrating dried yeast in water, is not always considered necessary depending on the brewer and the intended beer.

In the case of S-05, you may want a relatively clean flavor profile, so it may be worth rehydrating... especially if the gravity is over ~1.040.
 
Most yeasts just sit there. The explanation I've received is: dry yeast is extremely hygroscopic and sticky. Even sitting on top of the water, the yeast is absorbing water. Next time I use some S-04, I'll try to remember if it acts differently.
 
I have this 'problem' as well.

The effect is reduced if you can rehydrate in a container that is shallower and wider so there's more water surface area touching the yeast.

I just use a pyrex beaker, after about 15 minutes I give it a good stir, and again after about another 5 minutes then pitch., haven't had any problems yet.
 
I don't rehydrate it at all and I've never had a problem. I'm careful to get my wort to the right temperature before pitching.
 
Yes, I have noticed this as well. Seems pretty much impossible to execute the instructions as stated (suspend without stirring while it soaks up water, then stir after ~15 min). I think denimglen hit it right on about using a shallower, wider container.
 
Viability of the yeast is lower without re-hydrating properly. There still are enough active yeast to ferment, but you are also essentially throwing a bunch of sick or dead yeast in your beer. I prefer not to do that.
 
I fill a sanitized quart measuring cup with cooled wort, and dump the yeast on top. Cover with sanitized foil for a few minutes, then mix it up with a sanitized whisk.

Since I always need a blowoff tube by the next morning, I must be doing something right.

;)
 
Same experience here with the 04 and 05 yeasts. So it's not just you, all my beer has turned out fine so I wouldn't worry too much.
 
I advocate rehydration of all dry yeast but admittedly I do dry pitch US-05 and Nottingham if the beer is below 1.060. As long as you know you're killing a good portion of the packet, go ahead and do it. If you find a little downtime during the boil, why not rehydrate?
 
Plastic lidded container allows me to shake it up a bit without introducing a stirring device. I know it is not exactly what the directions call for but it is easier. Also direct pitch seems to work well for me if I forget to rehydrate.
 
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