Rehydrate dry yeast in pre-boiled wort?

[seanppp]

I was wondering if it would be a good idea to rehydrate my dry yeast in a cup or so of pre-boiled wort brought to 95 degrees or so? Does anybody do this?

Or perhaps even the post-boiled wort (if I am taking 40 mins for a hopstand and 20 for a whirlpool)?

What do you think?

 

[ShaineT]

You'll get answers on both sides with this. You can lose some % of cells by not rehydrating but if the manufacturer says pitch directly then they likely have already accounted for this in the present cell count. For myself it seems redundant as it already gets hydrated in my chilled wort and if I've oxygenated well there will be a healthy growth phase. If I'm to bother with rehydration then I might as well do starters with liquid yeast, which I already do btw.

 

[Veronis]

I wouldn't use wort. Rehydrate dry yeast in water.

"Re-hydration of yeast in plain water is strongly recommended because of the principles of osmosis. In a wort with a high concentration of dissolved sugar, the water that the yeast needs cannot be drawn across the cell membrane to wet it. The water is instead locked up in the wort, hydrating the sugars." -John Palmer

Source: http://www.howtobrew.com/section4/chapter21-1.html

John's method for rehydrating dried yeast: http://www.howtobrew.com/section1/chapter6-5.html

 

[seanppp]

Excellent, thanks.

I like that Palmer method, yet I've now noticed that ShaineT suggested, my packet of Safale 05 says to sprinkle it directly in the wort!

So what should I do? Listen to Palmer or listen to the yeast manufacturer?

 

[g-star]

Excellent, thanks.

I like that Palmer method, yet I've now noticed that ShaineT suggested, my packet of Safale 05 says to sprinkle it directly in the wort!

So what should I do? Listen to Palmer or listen to the yeast manufacturer?

The yeast manufacturers are trying to make the process idiot-proof with the "sprinkle into wort" directions. This will make beer, but is not optimal in terms of cell count/health. The well documented and valid reasons for re-hydrating in sterile water are given above, and should be followed if one wants to make the best beer possible.

 

[Veronis]

^ This.

I've learned to lean toward what John says. Yes you can sprinkle the yeast on the wort directly, but some of the yeast doesn't make it as a result.

Rehydrating in water like John says will give you a more attenuative fermentation, less likely to get stuck, etc.

 

[biertourist]

Umm... I think everyone's missed the obvious MAJOR PROBLEM in using pre-boiled wort.

Pre-boiled wort still has all sorts of nasty bacteria living in it; you do NOT want to use pre-boiled wort as your starter as you can't boil the starter later without killing your brewing yeast. This means that your starter will be pitching a load of stinky sour mash bacteria along with your yeast starter.

Using pre-boiled wort for a starter is a bad, bad idea. Don't do it!
(Unless when you say "95 degrees" you mean 95 degrees celcius for a while which should pasteurize the starter wort and that would be fine.)

-Your technique is safer if you're an extract brewer but I still wouldn't chance it and I'd definitely recommend using only BOILED WORT for your starter.



I'd say the safe way to do what you're thinking is to let the beer get to a boil in the kettle for 10 minutes and then pull enough liquid off for your starter using a pyrex measuring cup (glass would shatter) and then use this more dilluted wort for your starter. -The proteins in the starter won't yet be coagulated so it could lead to chill haze problems down the line but if it's a small 1-2 liter starter it's probably not a big deal; for a 1 gallon lager starter I wouldn't use this method and would stick to DME-based starters.

Adam