Do people rehydrate a sachet of yeast in chilled wort?

I am wondering if i should rehydrate my safale S0-4 dry yeast in a small glass of chilled wort (from the very same batch I am working on) for better yeast health. Any idea/experience on this one and the use of dry yeast directly from the sachet vs the use of rehydrated (in water or wort) dry yeast?

I am asking because I suspect that my yeast health is not flawless and some auto autolysis occurs during the fermentation and I am looking for ways to improve.

UPDATE: IT IS A BAD IDEA TO REHYDRATE IN CHILLED WORT. According to the book "Yeast"from Chris White and Jamil Zainasheff, if you do so, you simply end up damaging the yeast cells. They say that high levels of sugar, nutrients, hop acids, or other compounds can enter freely and damage the cells. This is due to the fact that during the first moments of rehydration, yeast cells can't regulate what passes through the membrane.

Basically, this makes us think and reconsider the option of pitching dry yeast straight from the sachet....since what I have just mentioned is what kills 50% of the total yeast cells at pitching.

Its recommended u use just water as they have reserves saved up and are ready to get right to work. Some have posted on here that rehydrating in a solution with sugar is counter productive. But others report sprinkling straight on top of the wort without rehydrating and have said they don't notice any difference.

The more u research the more you'll see there is a clear line between people who do rehydrate and people who just sprinkle right on top.

the whole point of rehydrating is to get the yeast active without the osmotic shock they can get from going straight into a very sugary wort. thus either rehydrate properly, in water, or skip it and sprinkle on the wort. rehydrating in a smaller amount of wort is just an extra step and accomplishes nothing.

Rehydrate in warm, sanitary water. If you search, you should be able to find the yeast manufacturer's recommendations for the process - temperature, time, etc. Doing this will ensure you pitch the proper amount of yeast...the conventional wisdom is that if you do not properly rehydrate up to 50% of your yeast will die...properly rehydrating the yeast in water basically gently wakes them up and prepares the cells...when you just dump them into wort, the high sugar, low pH environment is too much for the yeast cells to manage.

dinnerstick said:

the whole point of rehydrating is to get the yeast active without the osmotic shock they can get from going straight into a very sugary wort. thus either rehydrate properly, in water, or skip it and sprinkle on the wort. rehydrating in a smaller amount of wort is just an extra step and accomplishes nothing.

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+1
Putting a few of the thoughts together, the dehydrated yeast don't have much control over their cell walls - they basically take in everything. Once they're rehydrated they'll act as normal.

I always just boil a little bit of water on the stove while heating up my strike water. Put a lid on it then let it sit on the stove and cool on its own while I brew. By the time I'm ready to rehydrate the water is usually around 80 - 90 degrees F. Which seems to be the recommended rehydration temp for a lot of dry yeasts. I have personally noticed a better taste and less lag time in rehydrated yeast beers than those I just sprinkled.

It doesn't show up in darker beers. But in cream ales and pale ales I have tested I could taste a little stress in the ones where I just sprinkled dry. The rehydrated beers were a lot clenaer than those without rehydrating. I think the most beneficial thing is the reduced lag time. The yeast seem to take off better when properly hydrated.

Some yeast manufacturers also recommend that you attemperate the yeast to within at least 10*F of your wort temp. I rehydrate my yeast in water at temp per the yeast manufacturer (it can vary from around 80*F for US-05 up to 104*F for Lalvin 71B, as examples). I then add aliquots of the chilled wort at 10 min intervals until I'm within 10* of the wort temp. (I generally chill my wort to nearly 60*F, so there can be a pretty significant difference between the rehydration medium and the wort...)

There is also some data to suggest that using distilled water may be as osmoticly damaging to the yeast as wort. Tap water is probably fine, as long as it's not RO, but best practice may be to use a rehydration nutrient such as GoFerm. I have yet to actually play around with GoFerm (I have some, just haven't had the chance to use it) ...

All this may seem excessive, and I know there's the people out there who swear they brew the best barleywine ever by sprinkling a single 5 gm pack of yeast directly into their wort, but I think it's worth it to produce the healthiest yeast with the best pitch rate you can achieve...

Elysium said:

I am asking because I suspect that my yeast health is not flawless and some auto autolysis occurs during the fermentation and I am looking for ways to improve.

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why do suspect your yeast health is bad? i really doubt you are experiencing autolysis which happens only under extreme (for yeast) conditions: high heat for long periods of time, top pressure, O2 deficiency, high gravity among other things.

If rehydrating is so important why does fermentis packages just say "Pitching: Sprinkle into wort"?

steinsato said:

If rehydrating is so important why does fermentis packages just say "Pitching: Sprinkle into wort"?

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because it will work that way and its easy. Manufacturers like to make things easy for the customer...even if it sacrifices quality a little.

Most reliable yeast companies will suggest hydration. Stressing the yeast (ie pitching dry into wort) will create more mutations and ensure a poor yeast health if you were to wash it. In that case, you had better throw it out and buy a new packet. Who makes more money that way?

Also; the higher the stress on the yeast, the more healthy yeast you need to pitch. Pitch one packet of dry onto a batch of ris or barley wine. Go ahead... I dare you

steinsato said:

If rehydrating is so important why does fermentis packages just say "Pitching: Sprinkle into wort"?

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If you read their instructions for professional brewers, you'll see they say to rehydrate (http://www.fermentis.com/wp-content/uploads/2012/02/SFA_S04.pdf). Rehydrating will give a better fermentation...assuming you can keep everything sanitary during the rehydartion process. Fermentis assumes professional brewers know how to do this. They also assume that homebrewers do not..or at least a sufficient proportion of them do not, so it is safest to just say "sprinkle into wort".