Rehydrating yeast

Should i rehydrate the yeast that comes with a home brew beer can before i pitch?

Yes, the yeast is shocked and can lyse apart with the sudden rehydrating in sugary wort. Rehydrate first or you'll lose about half of the cell count right out of the gate.

Ok so what's involved in rehydrating your yeast how do you do it ?

Boil about a cup or two of distilled water for 5-10 minutes, you will need 4oz of water per packet of dry yeast. Keep in mind some will boil off. It's ideal if you can put a tiny pinch of gypsum or calcium chloride in the water before you boil it. The yeast like the calcium. When the water cools down to 80-90* add the yeast packet to 4oz of the water and let it sit. Do not stir. Once the concoction has cooled down to about 70* you can stir it up and pitch it in your wort.

SC_Ryan said:

Boil about a cup or two of distilled water for 5-10 minutes, you will need 4oz of water per packet of dry yeast. Keep in mind some will boil off. It's ideal if you can put a tiny pinch of gypsum or calcium chloride in the water before you boil it. The yeast like the calcium. When the water cools down to 80-90* add the yeast packet to 4oz of the water and let it sit. Do not stir. Once the concoction has cooled down to about 70* you can stir it up and pitch it in your wort.

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Don't use distilled water! Unless you add the minerals you suggest.

You get osmotic shock by using distilled, but instead of the cell walls letting in too much sugar, you get the interior of the cell trying to move to the lower density solution (the distilled water).

A 50:50 wort:water mix can also be used.

ChillWill said:

Don't use distilled water! Unless you add the minerals you suggest.

You get osmotic shock by using distilled, but instead of the cell walls letting in too much sugar, you get the interior of the cell trying to move to the lower density solution (the distilled water).

A 50:50 wort:water mix can also be used.

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Can you provide a source for this? Not saying you're wrong, I just haven't heard that.

I proof my yeast, then I know its good. It gives it a good start.

David

Different manufacturers have different info on rehydrating dry yeast. Some say it is really important while others say you don't need to at all. YMMV

biestie said:

Can you provide a source for this? Not saying you're wrong, I just haven't heard that.

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A scientist/project leader who previously worked at lallemand told me while in a lab session with commercial brewers from my part of the country.

It makes sense if you about the definition of osmosis:
"The movement of a lower density solution through a semi-permable membrane to a solution of higher density". Or something like that.

Basically, it works both ways. Until the cell walls are built up, using the hydrogen bonds of water to 'reorganize' them, the cells can't control what goes in or out so you don't want a high density solution such as wort, or too low such as distilled/RO water.

BMBARON said:

Should i rehydrate the yeast that comes with a home brew beer can before i pitch?

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What kind of yeast is it? I always rehydrate my dry yeast and have actually started doing it in a "stirred vessel" (i.e. glass measuring cup with a small stir bar on my stir plate). I've copied what Fermentis has to say on the matter and pasted it below (from the S-04 product sheet):

"Re-hydrate the dry yeast into yeast cream in a stirred vessel prior to pitching. Sprinkle the dry yeast in 10 times its own weight of sterile water or wort at 27C ± 3C. Once the expected weight of dry yeast is reconstituted into cream by this method (this takes about 15 to 30 minutes), maintain a gentle stirring for another 30 minutes. Then pitch the resultant cream into the fermentation vessel.

Alternatively, pitch dry yeast directly in the fermentation vessel providing the temperature of the wort is above 20C. Progressively sprinkle the dry yeast into the wort ensuring the yeast covers all the surface of wort available in order to avoid clumps. Leave for 30 minutes and then mix the wort e.g. using aeration."

I haven't rehydrated dry yeast since '96... have used SO4, S23 and Nottingham commercially without rehydration and saw zero difference in the finished product. I don't remember where the thread was, but someone had a vid up where they did a side-by-side comparison of dry yeast; rehydrated vs dry, and aerated vs non aerated. The progress of the fermentation was slightly different, but in the end they all ended up at the same place.

I put my yeast in the ferm prior to knockout... whether that means dumping int into a unitank in a brewery, or in the bottom of a bucket, and running the wort in after. My beers have an average lag time of about 6 hours from knockout to signs of active ferment. Works just fine for me... good starts, clean beer and one less possible source of infection.

Just dumped a 05 onto my wort. First time ever but lately I have tasted Damn good beer made with 05 and just dumping on wort.

Don't rehydrate, waste of time. I used to rehydrate my safale 05, but stopped many brews ago, just go to their website for instructions on pitching dry.

Dry pitching or rehydrating, either way you are going to make beer. Same goes with temp controls during fermentation or the pH balance of your water. IMO the more you do to utilize the optimal conditions for your brew, the better it will be.

I'd reccomend rehydrating. It only takes several minutes and it's and easy and efficient way of optimizing the conditions for your batch.

Mase said:

I'd reccomend rehydrating. It only takes several minutes and it's and easy and efficient way of optimizing the conditions for your batch.

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I've done it both ways, at the home scale and on commercial systems from 15-50bbl... the end product was the same. Why fool with it, adding an extra step that includes an (albeit small) increased risk of contamination? All that matters is what hits the glass.

Whatever works for you, if you have success with it either way that's awesome. I've just tried it both ways and noticed a difference. Just my 2 pennies.