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Jack Horzempa
New Member
Username: Jack_horzempa
Post Number: 4
Registered: 02-2007
Posted From: 38.243.104.19
| | Posted on Thursday, May 03, 2007 - 04:08 pm: | 
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I am going to brew an Oatmeal Stout tomorrow using Coopers Dry Ale Yeast (7 gm packet). There are no rehydration instructions on the packet. Does this dry yeast benefit from rehydration? If so, what is the recommended rehydration temperature (e.g., the same as Danstar dry yeasts)? |
Tex Brewer
Member
Username: Texbrewer
Post Number: 143
Registered: 03-2004
Posted From: 216.62.203.81
| | Posted on Thursday, May 03, 2007 - 05:51 pm: |
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I've used Coopers a fair bit and have always rehydrated it. Results have always been good. I cannot believe that that does not help. |
Dan Listermann
Senior Member
Username: Listermann
Post Number: 4297
Registered: 03-2004
Posted From: 216.23.59.245
| | Posted on Thursday, May 03, 2007 - 06:24 pm: |
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I never rehydrate dry yeast and get good results. At least to me, rehydration may only be marginally useful and has unnecessary risk. Others are perfectly free to disagree.
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Tex Brewer
Member
Username: Texbrewer
Post Number: 145
Registered: 03-2004
Posted From: 216.62.203.81
| | Posted on Thursday, May 03, 2007 - 07:47 pm: |
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From How To Brew, by John Palmer:
Chapter 6 - Yeast
6.5 Preparing Yeast and Yeast Starters
Preparing Dry Yeast
Dry yeast should be re-hydrated in water before pitching. Often the concentration of sugars in wort is high enough that the yeast can not draw enough water across the cell membranes to restart their metabolism. For best results, re-hydrate 2 packets of dry yeast in warm water (95-105°F) and then proof the yeast by adding some sugar to see if they are still alive after de-hydration and storage. |
Bill Pierce
Moderator
Username: Billpierce
Post Number: 7023
Registered: 01-2002
Posted From: 24.57.224.220
| | Posted on Thursday, May 03, 2007 - 07:52 pm: |
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On the other hand, Fermentis recommends against rehydrating their dry yeast. Frankly, I'm not sure what to believe or whether in fact it makes that much difference. |
Tex Brewer
Member
Username: Texbrewer
Post Number: 146
Registered: 03-2004
Posted From: 216.62.203.81
| | Posted on Thursday, May 03, 2007 - 08:01 pm: |
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Cooper's web site has extremely simple kit instructions, and merely says to sprinkle the yeast. They are making it idiot proof, but we can do much better. Here's a FAQ from http://www.clickabrew.com/newsletter/news-102005.htm
Should I rehydrate my beer yeast or just sprinkle it on?
Beer and wine kit manufacturers instruct you to sprinkle the yeast on top of the wort or must but yeast manufacturers tell us it’s very important to rehydrate the yeast. So who do we listen to?
To get the highest number of viable cells and strongest fermentation you should follow the yeast manufacturers instructions and rehydrate the yeast. But there is one problem with this. If you don’t follow the rehydration instructions exactly you could end up damaging more cells than by just sprinkling. That’s why you are instructed by kit manufacturers to sprinkle. It’s really a numbers game. They believe that there will be many more failures caused by improper yeast rehydration than failures caused by yeast damage from sprinkling.
We recommend that you rehydrate if you are sure that you will follow the directions exactly. If you're the type of person who rather not bother with details then go ahead and sprinkle your yeast. |
Chumley
Senior Member
Username: Chumley
Post Number: 4762
Registered: 02-2003
Posted From: 63.118.227.254
| | Posted on Thursday, May 03, 2007 - 08:44 pm: |
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I agree with Dan Listermann. |
Tex Brewer
Member
Username: Texbrewer
Post Number: 147
Registered: 03-2004
Posted From: 216.62.203.81
| | Posted on Thursday, May 03, 2007 - 10:21 pm: |
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Microbiologists I have talked to about this say that putting the dry yeast into wort will shock the yeast and kill many cells because of the osmotic pressure from sugars passing through the dry cell walls. They say the cells need to be rehydrated so that the cells fill with water, and membranes can effectively filter and buffer the sugars. the more concentrated the wort, the more important this is. Where is Fredrik? |
Bill Pierce
Moderator
Username: Billpierce
Post Number: 7025
Registered: 01-2002
Posted From: 24.57.224.220
| | Posted on Thursday, May 03, 2007 - 11:05 pm: |
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Here is Dr. Clayton Cone, the retired head of R&D for Lallemand, on the subject of rehydration for 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 105°F. Most of them closer to 105°F. 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 65°F the yeast leached out more and more of its insides damaging the 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 deionized 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 add to the wort. You just do not get the added benefit of that sudden burst of energy. We also recommend that you attemperate the rehydrated yeast to with in 15°F of the wort before adding to the wort. Warm yeast into 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 attemperation 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 with out 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 cell you still have 8 billion cells per gram that can go on to do the job at a slower rate.
The manufacturer 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 beer maker should keep in mind is that Active Dry Yeast is dormant or inactive and not inert, so keep refrigerated at all times. Do not store in a tin roofed warehouse that becomes an oven or on a window sill that gets equally hot.
Active Dry Yeast looses 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. |
Bill Pierce
Moderator
Username: Billpierce
Post Number: 7026
Registered: 01-2002
Posted From: 24.57.224.220
| | Posted on Thursday, May 03, 2007 - 11:15 pm: |
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I'm recalling this discussion from earlier posts, and it's beginning to come back into focus. Forgive me for my slightly fuzzy memory and also for not thoroughly searching the archives.
I believe the consensus (with some dissenting opinion) is that rehydration is best practice for dry yeast, especially if pitched into high gravity wort. However, there are some risks, both from less than stringent sanitation and less than optimal procedure. If you are the fussy brewer type, by all means rehydrate, but pay attention to Dr. Cone's instructions above. If you are more of the RDWHAHB school of brewing, go ahead and sprinkle the dry yeast onto the wort. As we all know, beer has been brewed for thousands of years in spite of ignorance and apathy. It's just that some people want to increase the odds even more in their favor.
(Message edited by BillPierce on May 03, 2007) |
Chumley
Senior Member
Username: Chumley
Post Number: 4763
Registered: 02-2003
Posted From: 63.118.227.254
| | Posted on Thursday, May 03, 2007 - 11:24 pm: |
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I still agree with Dan Listermann. |
Paul Hayslett
Senior Member
Username: Paulhayslett
Post Number: 1225
Registered: 02-2002
Posted From: 71.234.46.245
| | Posted on Friday, May 04, 2007 - 01:57 am: |
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Hey, it's DRY yeast. US$1.20 a packet, last I checked. So buy 3 and sprinkle them all. If 60% die, who cares? You'll still have enough to do the job. You'll avoid the sanitation risk. And it will still cost you 1/2 of what liquid yeast costs.
I very, very rarely use dry yeast, but when I do I just sprinkle in 22g and slam the lid. Life's too short to fuss over a dollar's worth of yeast.
"Cornbread and butter beans and you across the table,
Eatin' beans and makin' love as long as I am able,
Hoein' corn and cotton too and when the day is over,
Ride a mule you crazy fool and love again all over."
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Colby Enck
Intermediate Member
Username: Thecheese
Post Number: 419
Registered: 06-2003
Posted From: 70.44.68.25
| | Posted on Friday, May 04, 2007 - 05:17 pm: |
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"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."
Damn, I didn't think yeast cells were that big. |
Jack Horzempa
New Member
Username: Jack_horzempa
Post Number: 5
Registered: 02-2007
Posted From: 63.28.96.219
| | Posted on Friday, May 04, 2007 - 05:52 pm: |
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I want to thank everybody for their responses to my query. I just pitched the Coopers yeast into my Oatmeal Stout and I decided to not rehydrate (I just sprinkled it in and 'mixed' in in with an egg whisk). I have made this same batch of Oatmeal Stout before (twice before; a kit from Dan Listermann). I am somewhat embarrased to admit that I do not rememner whether I have rehydrated previously (I did not note this in my records). I am guessing that I did not rehydrate since Dan's instructions did not mention this.
I use dry yeast when the beer style permits (IPA, English Bitter Ale, Oatmeal Stout, etc.). I typically use Danstar yeasts (Nottingham and Windsor) and I always rehydrate them per the Danstar instructions. I once used Fermentis US-56 in my 'house' IPA. I rehydrated it as I always did with the Danstar yeasts but this batch did not ferment well (O.G. 1.053; F.G. 1.022). With the same 'malt bill' the Nottingham would finish at 1.012. I am guessing that rehydrating the US-56 caused this poor ferment?
Anyhow, I have resolved to just follow the manufacturer's instructions with respect to rehydrating:
- Rehydrate Danstar yeast
- Do not rehydrate Fermentis yeast (although I have never used this yeast again since I was not pleased with the past performance)
- Coopers yeast? (I still do not know what the manufacturer's recommendation truly is for this yeast).
Separate message to Dan Listermann: You Oatmeal Stout kit makes an EXCELLENT beer! |
Dan Listermann
Senior Member
Username: Listermann
Post Number: 4302
Registered: 03-2004
Posted From: 216.23.59.245
| | Posted on Friday, May 04, 2007 - 06:28 pm: |
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Jack, tomorrow, for National Homebrew Day, I intend to make 15 gallons of the Oatmeal stout. It is my brother's favorite and I have promised a batch to the guy who has supplied me with birds. I might split five gallons worth to give various yeasts a spin.
Thanks for the nice words!
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Brews and Views Archive 2007 
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