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brewfan86 · 10-10-2012, 07:20 AM

Do you guys recommend this?? I've seen videos on YouTube and I'm thinking of doing it for my second batch. I bought a northern brewer kit tht came with safale US -05 ale yeast which on the packet says PITCHING: sprinkle into wort. Does this mean I can't rehydrate or shouldn't?

**tally350z** · 10-10-2012, 07:24 AM

It's not required. I have personally never rehydrated my dry yeast. You can just sprinkle onto the wort.

chemicalcraig · 10-10-2012, 07:41 AM

it's not required, but is recommended. By rehydrating you make the cell walls pliable, getting the yeast ready to do their job in a healthy and effective manner. If you sprinkle directly it shocks a lot of the yeast and can effectively decrease the viable cell count. But given the relatively high cell count in each packet, you'll be fine. I simply sprinkled the yeast for years, producing award winning beers, and still do on occasion when I've forgotten to rehydrate with no noticeable detrimental effects. An added benefit to using dry yeast is that you don't need to aerate the wort, though this can increase lag time if that worries you.

ETCS · 10-10-2012, 08:59 AM

I'm with tally.....whenever I use dry yeast, I just dump the dry yeast in and shake the carboy. Never had a problem.

**unionrdr** · 10-10-2012, 12:00 PM

I like to re-hydrate,as it decreeses lag time. And I always aerate the wort. Regardless of being dry or liquid,the yeast still need o2 for the reproductive phase.

progmac · 10-10-2012, 12:07 PM

Here are the FULL pitching instructions from the product spec 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 (80F ± 6F). 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 (68F). 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.

friday · 10-10-2012, 12:12 PM

Being that this post is in the new brewers forum I would just toss it in.

Yes I do rehydrate but it's ok if you don't. Does it really make a difference, as a new brewer probably not.

**unionrdr** · 10-10-2012, 12:12 PM

Yup,the cream works real well. Pitched late last night with re-hydrated US-05 on a PM pale ale. Co2 is building up atm,but had to burp test it. Blow off should dtart in a lil while.

**Paulgs3** · 10-10-2012, 01:46 PM

This is a copy/paste from one of my bookmarks:

Dr. Clayton Cone on rehydrating dry yeast - 2000

From: Dan Listermann
Subject: Dry Yeast Hydration

My question to Dr. Cone regards yeast rehydration. All the packages of yeast contain instructions for rehydration yet they all ferment just fine without it. I have to believe that such a procedure may be theoretically beneficial, however it would seem to be marginally useful at least on a homebrew scale.

I own a home brew shop and a very common phone call is the "My beer is not fermenting" problem. I go through the list of potential causes; plastic bucket lid leaks, too cold, etc. About twice a week the caller will indicate that he rehydrated the yeast. This is a strong signal that the
yeast has been damaged and will need to be replaced. I have come to the conclusion that, since rehydration is not necessary to ferment beer properly and there is a strong chance that the yeast will be damaged in a botched rehydration, it is not desirable to recommend such a procedure. Just how important is rehydration and is it worth the risk?

Dan,
I appreciate your dilemma. It is a universal problem for those that market Active Dry Yeast.

Let me give you some facts regarding rehydration and you can decide for yourself where you want to compromise.

Every strain of yeast has its own optimum rehydration temperature. All of them range between 95 F to 105F. Most of them closer to 105F. The dried yeast cell wall is fragile and it is the first few minutes (possibly seconds) of rehydration that the warm temperature is critical while it is
reconstituting its cell wall structure.

As you drop the initial temperature of the water from 95 to 85 or 75 or 65F the yeast leached out more and more of its insides damaging each cell. The yeast viability also drops proportionally. At 95 - 105 F, there is 100% recovery of the viable dry yeast. At 60F, there can be as much as 60% dead cells.

The water should be tap water with the normal amount of hardness present. The hardness is essential for good recovery. 250 -500 ppm hardness is ideal. This means that de-ionized or distilled water should not be used. Ideally, the warm rehydration water should contain about 0.5 - 1.0% yeast extract

For the initial few minutes (perhaps seconds) of rehydration, the yeast cell wall cannot differentiate what passes through the wall. Toxic materials like sprays, hops, SO2 and sugars in high levels, that the yeast normally can selectively keep from passing through its cell wall rush right in and seriously damage the cells. The moment that the cell wall is properly reconstituted, the yeast can then regulate what goes in and out of the cell. That is why we hesitate to recommend rehydration in wort or must. Very dilute wort seems to be OK.

We recommend that the rehydrated yeast be added to the wort within 30 minutes. We have built into each cell a large amount of glycogen and trehalose that give the yeast a burst of energy to kick off the growth cycle when it is in the wort. It is quickly used up if the yeast is
rehydrated for more than 30 minutes. There is no damage done here if it is not immediately added to the wort. You just do not get the added benefit of that sudden burst of energy. We also recommend that you atemperate the rehydrated yeast to within 15F of the wort before adding to the wort. Adding warm yeast to a cold wort will cause many of the yeast to produce petite mutants that will never grow or ferment properly and will cause them to produce H2S. The atemperation can take place over a very brief period by adding, in increments, a small amount of the cooler wort to the rehydrated yeast.

Many times we find that warm water is added to a very cold container that drops the rehydrating water below the desired temperature.

Sometimes refrigerated, very cold, dry yeast is added directly to the warm water without giving it time to come to room temperature. The initial water entering the cell is then cool.

How do many beer and wine makers have successful fermentations when they ignore all the above? I believe that it is just a numbers game. Each gram of Active Dry Yeast contains about 20 billion live yeast cells. If you slightly damage the cells, they have a remarkable ability to recover in the rich wort. If you kill 60% of the cells you still have 8 billion cells per gram that can go on to do the job at a slower rate.

The manufacturers of Active Dry Beer Yeast would be remiss if they offered rehydration instructions that were less than the very best that their data indicated.

One very important factor that the distributor and brewer should keep in mind is that Active Dry Yeast is dormant or inactive and not inert, so keep it refrigerated at all times. Do not store it in a tin-roofed warehouse that becomes an oven or on a windowsill that gets equally hot.

Active Dry Yeast loses about 20% of its activity in a year when it is stored at 75 F and only 4% when refrigerated.

The above overview of rehydration should tell you that there is a very best way to rehydrate. It should also tell you where you are safe in adapting the rehydration procedure to fit your clients.

Clayton Cone.

**Beer-lord** · 10-10-2012, 01:52 PM

I still do it dry and rehydrated but rehydrating it definitely decreases lag time for me. There is not doubt about that.