Should I Re-hydrate Dried Yeast?

[Goose]

I thought this was a good approach to yeast (but not life in general):

"[SIZE=medium]Sure, some yeast die if pitched dry direct into the wort. But maybe this is a good thing. They are weak yeast cells with cell walls that can't withstand the osmotic pressure of the wort. Good. Let the buggers die, and ferment your beer with decendants of the remaining strong, thick walled yeast. [/SIZE][SIZE=medium]Call it a eugenics approach."[/SIZE]

That implies that the yeast that could not withstand the osmotic pressure could also not process wort.

Not sure about that assumption. Just because you can lift a ton, does that mean you can also spell it ?

 

[danestead]

You know what, if getting the rehydration water the right temperature is too much dicking around, I might just throw some hot water in my mash next time and not bother using a thermometer because that is also too much dicking around for my busy life.

Yes my statement above is taking it to extremes, but seriously, any big company wanting exact repeatability, and I am talking mega breweries like Heineken etc, will be testing every single parameter and doing it the same each time to ensure repeatability. The smaller micro breweries like Feral, Bridge Road Brewers, Modus Operandi etc wouldn't likely measure as many parameters as the likes of Heineken in terms of yeast labs, measuring diacetyl through gas chromatography or however they do it but I see sticking a sanitised thermometer in my hydration water quite simple, and in my opinion, something worth doing to give myself the best possible chance of producing a quality product which I can reproduce time after time.

I strive to do everything exactly the same each time so that when I brew that particular brew again, it comes out the same.

 

[Feldon]

That implies that the yeast that could not withstand the osmotic pressure could also not process wort.

Not sure about that assumption. Just because you can lift a ton, does that mean you can also spell it ?

Not an assumption, a postulation.

 

[danestead]

"[SIZE=medium]Sure, some yeast die if pitched dry direct into the wort. But maybe this is a good thing. They are weak yeast cells with cell walls that can't withstand the osmotic pressure of the wort. Good. Let the buggers die, and ferment your beer with decendants of the remaining strong, thick walled yeast. [/SIZE][SIZE=medium]Call it a eugenics approach."[/SIZE]

I read that as the living cells at the end are possibly from stronger genes if you will, however they have had the **** kicked out of them and are lying on the foot path almost unconscious.

 

[Goose]

Not an assumption, a postulation.

Indeed your postulation could be correct.

But what if I postulate that the yeast that would survive by rehydration in water, but also likely to die in a direct wort pitch, are perhaps better at the fermentation task ?

Ok enough crap, just for a laugh

 

[wobbly]

Has there ever been a serious side by side brew comparison conducted?

This is the the only comparison I have seen where there is tabulated results comparing re-hydration "Temperature vs Water vs Wort". Then if the results are correct (and there is nothing to say they aren't) then re-hydration in wort results in about only 56% viability compared to that re-hydrated in water

There have been lots of comments along the lines of "show me the test results" rather than just quoting so called published opinions with out detailed supporting tests results.

Not suggesting for one moment that this test will change the view of those that have committed to the view that it is not necessary (and is possibly a waste of time) to re-hydrate but for the rest of us it supports that we are on the right path

This result seems to support data/methodology by the manufacturers to re-hydrate for optimum performance and also supports Mr Malty values of around 20 billion cells per gram

http://seanterrill.com/2011/04/01/dry-yeast-viability/

Cheers

Wobbly

 

[danestead]

Another thing I've been thinking about is that I believe most people would agree that rehydrating yeast will result in a greater number of viable, healthy yeast, however I think a lot tend to argue that not rehydrating is better because they don't want the extra effort or additional sanitation risk.

I think those 2 things are different questions.

1. Does rehydrating or dry pitching produce more viable, healthy yeast?
2. Do you prefer to rehydrate or dry pitch your yeast? - I don't think this question refers to numbers of viable yeast, although I think many people misunderstand it as such.

 

[Moog]

I have a question regarding the method of rehydrating.....It I use some boiled water cooled to the right temp, If I have to let it sit for half an hour, then re-stir, the temp will have dropped of, what suggestions are there to keep it constant?
Would a stubby holder do the trick?

 

[Feldon]

Another thing that is seldom mentioned when people say they rehydrate their yeast is how they actually go about it, and in what time frame. Do it wrong and you'll kill a lot of your yeast cells.

Its actually quite a tricky procedure to do properly - stepping the water temp down from, say, 30C initially, in 5 or 10 degree increments down to pitching temp using doses of cooler wort . And more so if you intend to pitch the yeast into a low temp lager wort. And no stirring in the early stages of rehydration, and all the while you need to keep it all clean and sanitary as you go. You only have about half an hour from adding water to the dry yeast to eventually pitching the yeast slurry into the wort. Its not something I'd recommend to new brewers - there's enough to learn and accomplish in the early days without adding to the list.

 

[danestead]

I have a question regarding the method of rehydrating.....It I use some boiled water cooled to the right temp, If I have to let it sit for half an hour, then re-stir, the temp will have dropped of, what suggestions are there to keep it constant?
Would a stubby holder do the trick?

Personally, considering comfortable room temperatures are about 20-25 degrees, you shouldn't see much drop in the temperature of the water. For US-05 it is recommended to do it at 27 degrees +- 3 degrees, so I'd be surprised if it changed by more than a degree or 2. If you are really worried, warm it to 30 degrees and let it cool. It'll still be within the recommended temperature. Otherwise, you could sit it in a bigger container of water to regulate the temperature better.

I see the best temperature for rehydrating as something you want to get close to, but no need for nailing it to the tenths of a degree.

 

[danestead]

Another thing that is seldom mentioned when people say they rehydrate their yeast is how they actually go about it, and in what time frame. Do it wrong and you'll kill a lot of your yeast cells.

Its actually quite a tricky procedure to do properly - stepping the water temp down from, say, 30C initially, in 5 or 10 degree increments down to pitching temp using doses of cooler wort . And more so if you intend to pitch the yeast into a low temp lager wort. And no stirring in the early stages of rehydration, and all the while you need to keep it all clean and sanitary as you go. You only have about half an hour from adding water to the dry yeast to eventually pitching the yeast slurry into the wort. Its not something I'd recommend to new brewers - there's enough to learn and accomplish in the early days without adding to the list.

A text I read some time ago, which I can;t remember the name of, recommended pitching the rehydrated yeast within 8 degrees of the wort temperature. Thins could be done by putting it in the fridge and stirring every 5 mins.

 

[Benn]

Following on from wobbly's reply to my question earlier today, it would be interesting to taste the results of the same wort i.e double batch split between two identical fermenters fermented under exactly the same conditions. Only difference being that one fermenter gets sprinkled and the other gets rehydrated yeast. Surely it's been done.

 

[MHB]

Might be worth posting the results of the above experiment to save a few clicks:

Can you supply where that is from?
Is it from a valid source, or just a pretty picture that someone drew to illustrate an opinion.
Mark
Sorry found it, will read
Mark

 

[Elz]

So ideally the brewer should rehydrate in H2O at 33oC and the poor into worth at temp of 25oC. Optimum yeast use? In this scenario not using a starter.

 

[louistoo]

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.

Fermentis advises a period of just 45 min to one hour hydration with almost constant gentle stirring for last half an hour, at 27c + or - 3c
**** another hydration discussion huh, still following these directions and using correct amount has improved my beers I reckon.

 

[Ducatiboy stu]

Anyway, forgive me for re-posting from this from Stu's famous thread (http://aussiehomebrewer.com/topic/74450-re-hydrate-v-not/ ) (possibly flagrant disregard of forum rules. Forgive me for I know not what I do).

I know what you did,.....


For the love of god, lock that thread and appreciate it like a fine painting, with a beer in hand..


....that and I dont really think we need another 23 pages........

 

[Ducatiboy stu]

Following on from wobbly's reply to my question earlier today, it would be interesting to taste the results of the same wort i.e double batch split between two identical fermenters fermented under exactly the same conditions. Only difference being that one fermenter gets sprinkled and the other gets rehydrated yeast. Surely it's been done.

Actually, no it hasnt. Not on our sort of level. If it had we wouldn't be having this conversation.

Another thing that is seldom mentioned when people say they rehydrate their yeast is how they actually go about it, and in what time frame. Do it wrong and you'll kill a lot of your yeast cells.

Its actually quite a tricky procedure to do properly - stepping the water temp down from, say, 30C initially, in 5 or 10 degree increments down to pitching temp using doses of cooler wort . And more so if you intend to pitch the yeast into a low temp lager wort. And no stirring in the early stages of rehydration, and all the while you need to keep it all clean and sanitary as you go. You only have about half an hour from adding water to the dry yeast to eventually pitching the yeast slurry into the wort. Its not something I'd recommend to new brewers - there's enough to learn and accomplish in the early days without adding to the list.

And that is kinda the point.

Its not just a matter of just adding some warm water to a flask and sitting back....you could end up doing more damage than good.....

 

[Black Devil Dog]

 

[technobabble66]

That implies that the yeast that could not withstand the osmotic pressure could also not process wort.

Not sure about that assumption. Just because you can lift a ton, does that mean you can also spell it ?

Bingo. I'd assume the eugenics theory from DS is mostly tongue in cheek, but in case anyone is mildly influenced by it, all it means is that those cells that are strong at handling strong osmotic pressure have survived. This in no way indicates their ability to process wort in a way we would find favorable. In fact, it could be argued that those that "specialise" in osmotic pressure strength are more likely to be weaker in other areas, such as clean fermentation....
2c

 

[Benn]

Side by side experiment could be a good trial for a brew club etc, good number of blind tasters on hand to taste the results once it's all done.