hydrate or sprinkle ?

[Andy]

I pretty much follow the Fermentis rehydrate instructions (with the exception of the "maintain" stirring part).

Fermentis S04 datasheet -> www.fermentis.com/fo/pdf/HB/EN/Safale_S-04_HB.pdf

[EoinMag]

I feel I should also confess that since I increased my batch size I now routinely underpitch. I'm far too tight to use two packets of yeast so my 8 gallons have to make do with one packet (sprinkled). I'm such a bad man. I just don't deserve to make beer...

What types of beers do you tend to make? I think if you get into the paler beers and want to make good ones, you'll have to pay more attention to your yeast and also to the water treatment, both things that you can get away without doing when you are making darker beers normally.

[boingy]

I brew almost exclusively British ales, every shade from the palest ales through to the blackest stouts. The paler beers definitely benefit from water treatment and, imho, are every bit as good as commercial beers (occasionally you have to ignore the slight haze... ). I've just not seen any real difference in the yeast performance or end result with rehydration. However, like many others I have never hydrated exactly as per the instructions because I don't really have the facilities to constantly and gently stir yeast cream for 30 minutes. I rather suspect that the really popular dry yeasts like Notty and S04 are successful because they are robust and will cope with less than ideal treatment. In summary, my beer ain't broke, and sprinkling is just easier. Rehydration is a process that I choose to skip. Others should make up their own mind.

[raiderman]

I think you're right. I'm a great believer in superstition over science in brewing - lets keep it an art form! If something works then do it. I do the opposite with yeast but thats superstition for you!

[TC2642]

I rehydrate around the 30oC mark. I did use to sprinkle around four or five years ago but from my own empirical research I do think the yeast gets going a bit quicker.

[dedken]

For me, hydrating drastically reduces the time the yeast starts to get going. Sprinkled on wort, it would be at least 6 hours before the first bubbles appeared in the airlock. Rehydrated, it's less than 2 hours.

Maybe there are always exceptions to the rule. Yesterday evening (c. midnight) I rehydrated a sachet of saflager W34/70 and pitched. By the morning (07.00) it had not got going. Thankfully by the time I got home from work, after worrying about who i was going to contact for some emergency yeast which would actually be favourable to hops, it was going. Conversely, last time I used said yeast in January I dry pitched and it was virtually jumping out of the fv within 2 hours!

I used to dry sprinkle always, being of the mindset that the best way of rehydrating yeast was to dump it into a big vat of liquid. Having advanced as a brewer (I think, anyway!) and experienced a few yeast-related problems (like 72 hours for WLP013 to go off) I will routinely rehydrate dry yeast (or make starter for for liquid yeasts) just to check viability. I will never let 72 hours pass again without pitching emergency yeast!

[jimp2003]

I have always just sprinkled the dry yeast that I have used with kits. Now I have gone down the grain route using BIAB I have used liquid yeasts and made starters etc.

There is one thing about one of the methods mentioned for rehydrating dry yeasts that I can't get my head around (maybe I am just being thick ) - If you rehydrate using a wort made from DME and water, why is this good for the yeast but bunging it into the FV with your brew might kill off a lot of cells?

[beermonsta]

There is one thing about one of the methods mentioned for rehydrating dry yeasts that I can't get my head around (maybe I am just being thick ) - If you rehydrate using a wort made from DME and water, why is this good for the yeast but bunging it into the FV with your brew might kill off a lot of cells?

Edit: ooops - I was talking rubbish last night when I wrote the bit below! - Sorry, I'll re-edit now that I'm awake (and not intoxicated )

If you "bung the yeast dry into a FV with your brew" the yeast cells are very weak and will absorb everything around them including the acid, sugar and any other nasties. These could and do kill the yeast cells.
If you re-hydrate the yeast in pure water you are not subjecting the yeast to anything that will stress them. It will allow them time to build their cell walls and become active again before pitching them into the harsher wort environment.
As dried yeast has a good cell count for pitching, it's not worth propagating (making a starter) and running the risk of introducing infections. Instead, as dried yeast is cheap it's safer just to buy more.
If on the other hand you are using a liquid yeast/slant etc and your intention is to propagate the yeast (to make a starter) then this is where using a DME solution at the correct gravity is fine. If you do this though make sure you use DME and not any other sugar such as glucose/fructose (i.e. caster/granulated).
DME are maltose sugars (more complex) where as glucose/fructose are simpler sugars. This will ensure that if the yeast cells are re-used in another fermentation that they maintain the ability to convert the more complex sugars. If you selectively use just yeast that can only convert basic sugars such as glucose/fructose or sucrose then they will naturally loose the ability to convert the more complex sugars such as maltose - which just happens to be the main sugar in which that wort consist of.
In other words, yeast are weak when being "woken up". You need to treat them nice. That include temperature, Ph and not subjecting them to high sugar concentrations. If you treat them bad and subject them to nasty raw wort then they won't flurish and indeed die.

sorry about the original if you read it - It'll teach me not to post late on a friday night!

[Aleman]

If you rehydrate using a wort made from DME and water, why is this good for the yeast but bunging it into the FV with your brew might kill off a lot of cells?

You rehydrate using cooled boiled water at the rehydration temperature for the yeast strain you are using . . .you make a starter from DME and water . . .and with dry yeast that is a pointless futile exercise . . .unless you are making a 25L Starter

[Beer O'Clock]

OK, my 2 penneth worth. I have always been a sprinkler until my last AG. I decided to try something different. Once I've got a rolling boil, I ran 200ml (ish) of my wort into a pyrex jug. Placed in the sink (in water) to cool. At 22-23 degC I sprinkled my SO-4, covered with cling-film, then put aside.

I gave it a stir, then pitched into FV @ 20degC. It took off like a rocket. Bubbling away within 60min.

It takes little or no extra effort but gave me a good result. I shall continue with this practise until I discover a problem with it.

[Wolfy]

OK, my 2 penneth worth. I have always been a sprinkler until my last AG. I decided to try something different. Once I've got a rolling boil, I ran 200ml (ish) of my wort into a pyrex jug. Placed in the sink (in water) to cool. At 22-23 degC I sprinkled my SO-4, covered with cling-film, then put aside.

I gave it a stir, then pitched into FV @ 20degC. It took off like a rocket. Bubbling away within 60min.

It takes little or no extra effort but gave me a good result. I shall continue with this practise until I discover a problem with it.

Rehydrating in a small amount of the same wort you'll pitch the yeast into is no different to simply throwing the yeast into the fermentor.
You still risk killing many cells because they have not been reconstituted 'properly'.

But it worked for you and you were happy with the results, so no reason not to do it again (just compensate the pitching rate for the yeast you'll kill).

[Naich]

John Palmer says "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."

That's the reasoning behind rehydrating in plain water and why you shouldn't rehydrate with DME. Whether it is actually correct or not is another matter and one I'm not qualified to comment on.

[EoinMag]

John Palmer says "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."

That's the reasoning behind rehydrating in plain water and why you shouldn't rehydrate with DME. Whether it is actually correct or not is another matter and one I'm not qualified to comment on.

Yeah, it's a phenomenon called Osmosis.

"Osmosis is the movement of solvent molecules through a selectively-permeable membrane into a region of higher solute concentration, aiming to equalize the solute concentrations on the two sides."

http://en.wikipedia.org/wiki/Osmosis

Put simply because the sugar solution is full of long chain sugars those molecules are less likely to pass through a porous membrane than pure water is, so whereby liquid is going in and out of the cell wall at the same time, the tendency is for the liquid to collect on the side which has the sugary liquid in because less of it will pass through the membrane trying to dilute the sugar solution rather than trying to hydrate the cells, which is actually what you want, this can lead to cells bursting.

[leedsbrew]

. . .unless you are making a 25L Starter

[jimp2003]

If you rehydrate using a wort made from DME and water, why is this good for the yeast but bunging it into the FV with your brew might kill off a lot of cells?

You rehydrate using cooled boiled water at the rehydration temperature for the yeast strain you are using . . .you make a starter from DME and water . . .and with dry yeast that is a pointless futile exercise . . .unless you are making a 25L Starter

I always assumed cooled boiled water with dry yeasts but people talking about using DME and water for dry yeasts sounded a bit wrong...but if that method still gets you the results then that's what it's all about I guess