Should I Re-hydrate Dried Yeast?

[Truman42]

I got a bit confused when doing my first AG on re-hydrating dried yeast and was told different things on here about if it needs to be done or not. I think I may have worded my post wrong so I just wanted to clear things up.

Do we need to re-hyrdate yeast following John Palmers instructions show here.

re-hydrate yeast


Or with modern day yeasts is this something we no longer worry about and can I just pitch it dry? Im using US05.

Thanks heaps.

 

[argon]

Should you?... yes you'll get the best out of your yeast

 

[1975sandman]

I rehydrate US-05 by following the Fermentis instructions - add packet to 10 times it's own weight of boiled and cooled water into a sterilised glass jar at the start of the brew day, swirl gently every half hour or so to keep it mixed then pitch when wort at right temperature.

Note: I use an immersion chiller to chill to pitching temp.

 

[MarkBastard]

You don't have to, but it apparently gives better results. I often don't do it. I just sprinkle on top of the wort and don't even stir it in. Probably takes a better longer to kick off but I've never noticed a difference in the finished beer.

I always rehydrate when using dry lager yeast though.

 

[flano]

done both ....and cannot tell the difference.

 

[Mikedub]

I think of rehydrating yeast as foreplay, it puts it in the mood before you stick it in,

Just whacking it in dry could end in tears

 

[Fourstar]

if your incapable of following the fermentis directions (or whatever brand you use), just pitch the yeast dry. If you are capable of performing their instructions and rehydrating the yeast correctly. Do it, it will be benificial.

Read below to see why.

slightly :icon_offtopic: but highly relevant.

im sure they handled their yeast and more so prepared it correctly too. :icon_cheers:

This isnt a dry yeast bash and you will see why. Dry yeast is completely fine assuming you handle it correctly and pitch it at correct rates.

I overheard some interesting information that Chris White (whitelabs) was discussing regarding the use of dry yeast. I believe he estimated cell death of dry yeast if not rehydrated of close to 50%. AKA pitching direct to fermenter.

Now using that information, see the following. The dry yeast packets state on their spec sheet each packet contains 11.5g of yeast and the viability at packaging is 6 * 10 ^ 9 (6 billion cells per g) which equates to 69 billion cells in a packet.

What do whitelabs and wyeast have as a starting point? Around 31% more viable cells in a fresh smack pack/vial. (wyeast state 100 billion cells, whitelabs between 70 -140 billion cells.)

Now the figures above are assuming you pitch the dry yeast after rehydrating. If not, that figure could be closer to 65% less yeast if you decide to sprinkle the dry yeast directly onto the wort.


Now if we think about correct cell pitching rates, what cell count do you need for a 1.050OG 20L wort?

750000*20000*12.5 = 187.5 billion cells.

At worst, one non-rehydrated dry yeast pack will get you to 18%~ of that recommended cell count.
one smack pack/vial assuming 100% viability of a liquid culture at 100 billion cells = 53% if your cell count.

I know what option i would choose.

Smack pack + 1L starter. For those fond of dry yeast, atleast two rehydrated US05 packets.

 

[kymba]

man, do we really need another rehydration thread? did you do any searching at all?

 

[Dave70]

As far as I can tell, the only point of re-hydration is to 'proof' the yeast buy adding a teaspoon of sugar to a cup of water and making sure it fires up. Saves the fretting in a few days time when the fermenter's sitting there dead as the Ok Tedi tailings dam.
I think fresh, well handled dry yeast actually contains more cells than liquid smack packets. So there's little point making a starter for a regular batch.

Of more importance is a well aerated wort to get the party started.

 

[Fourstar]

As far as I can tell, the only point of re-hydration is to 'proof' the yeast buy adding a teaspoon of sugar to a cup of water and making sure it fires up.

You're actually lowering your viability by doing this as the propose of rehydrating yeast is to get it ready for the job. While the yeast are rehydrating, their cell walls are fragile and giving them medium to chew on doesnt do them any favours and you end up with fatalities. You should rehydrate on the correct temperature water only. not wort or other sugars. STARTERS on the other hand is essentially proofing/building cell count.

 

[manticle]

Forget John Palmer's instructions - follow the fermentis instructions found here: http://www.fermentis.com/fo/pdf/Tips-Tricks.pdf (scroll to the bottom of page 5).

I rarely rehydrate despite the alarmist cell counting evidence. I find little problems with this method. However if my beer is much above 1050 SG, I may rehydrate according to said instructions. It's easy enough and gives me peace of mind. I have made super tasty beers with a single pack of 05 in 1060 wort though (one of my recent ones got a fourth in Vicbrew) so it could just be one of those things to fuss over if you feel like it.

It's easy to make brewing complicated and sometimes it's fun but it's rarely necessary.

I reckon it's more important to get fresh, well handled yeast than to rehydrate.

 

[Bribie G]

I'll double check on this but I'm sure that in part 2 of "Your Shout" on the history channel an Australian Craftbrewery is clearly shown pouring a shitload of dried yeast from a bulk pack straight onto a brew. I remember thinking "I bet that's S-04 " :lol:
I'll fire up the IQ box later and have a look

I always rehydrate on the odd occasion that I use a fresh pack of dried, but it has been pointed out that anyone quoting Chris White is quoting a guy who makes a living out of liquid yeast.

 

[MarkBastard]

Regarding cell count and viability, all that is well and true, but what are the reported outcomes of under pitching and what levels of under pitching produce what outcomes?

Who knows if they're talking about a brew taking longer than normal to ferment? Maybe they're thinking of commercial breweries that can only have a certain fermentation tank used for a certain amount of days.

Does it make the beer funky? Under attenuated?

If people are under pitching and don't notice these issues, does it really matter?

 

[bkmad]

I always rehydrate on the odd occasion that I use a fresh pack of dried, but it has been pointed out that anyone quoting Chris White is quoting a guy who makes a living out of liquid yeast.

I think this is an important point. Pretty much every time I've seen a reference on this site regarding a 50% drop in viability when not rehydrating, the reference is the Chris White. I haven't seen any other data to back his statement up (not that I've gone looking for it).

 

[Steve@PMF82]

I think this is an important point. Pretty much every time I've seen a reference on this site regarding a 50% drop in viability when not rehydrating, the reference is the Chris White. I haven't seen any other data to back his statement up (not that I've gone looking for it).

I am pretty sure this has been posted here before, in exactly the same kind of thread, which should make the regurgitation police happy....
here it is anyway http://koehlerbeer.com/2008/06/07/rehydrat...r-clayton-cone/

 

[beerbog]

I've done both and haven't noticed any difference, same lag time and same amount of activity. Same FG after 14 days. It is easier just to sprinkle on top, providing you whip the wort up real good to oxygenate it first. :beerbang:

 

[bkmad]

I am pretty sure this has been posted here before, in exactly the same kind of thread, which should make the regurgitation police happy....
here it is anyway http://koehlerbeer.com/2008/06/07/rehydrat...r-clayton-cone/

Thanks for that.
I find it interesting that the temperature of the water can have a drastic effect on viability. Looks like I can improve my practices a bit as I've been rehydrating but not been too fussed on getting the water temp right.

 

[Greg.L]

In my experience, for beer it's fine to pitch dry yeast but for cider or wine you do need to rehydrate, it makes a big difference. The beer wort is so full of nutrient that the yeast recover quickly, but grape or apple juice are much tougher for the yeast to get going.

 

[DUANNE]

I think this is an important point. Pretty much every time I've seen a reference on this site regarding a 50% drop in viability when not rehydrating, the reference is the Chris White. I haven't seen any other data to back his statement up (not that I've gone looking for it).

there was a basic brewing podcast were another bloke did the lab work and came out with a similar result as well.

 

[Truman42]

man, do we really need another rehydration thread? did you do any searching at all?

Yes I did and found the same difference of opinions as I have on this thread.

Thank you to everyone for the informative replies. I will check out the link to the fermentis instructions, thanks Manticle once again.