Rehydrating Yeast

[jlietzow]

I was brewing a coffee porter extract kit today and realized at the last minute that the yeast that it was packaged with (Lallemand Nottingham) called for rehydration. I had tried to rehydrate yeast once before, but that batch was my only real failure and so I've avoided doing it again, just pitching dry (using mostly US-05 or US-04).

I considered just pitching dry, as the kit instructed, but decided that the yeast manufacturer probably knows best so I gave it a shot.

Checking the Lallemand web site they said to bring 4 oz sanitized water to 86-95 degrees and then sprinkle the yeast. Then wait 15 minutes, stir gently, then wait 5 more minutes. Throughout that time you're supposed to maintain the same 86-95 degree temp range. After that bring the rehydrated yeast to the same temp as the wort and pitch.

I boiled a little more than 4 oz water in a small pan and let return to about 90 degrees before sprinkling the yeast. However I struggled to maintain that temp for 20 minutes. As it got down near 80 degrees I turned the burner back on and tried to warm gently. I stopped heating when it got to 90 degrees and then just covered it and tried not to worry.

In the end the yeast looked and smelled healthy (frothy and smelled like fresh bread) so I am hopeful that I didn't screw up too much. However I'd sure like to do a better job of this next time.

Any suggestions for a more reliable (and hopefully simple) procedure for rehydration would be greatly appreciated!

 

[sketerbuck]

I wouldn't put the yeast back on the heat but it sounds like you did fine. You could probably let it drop to your pitch temp.

 

[ancientmariner52]

I'm sure the temperature range Lallemand specifies was determined to be optimum. That doesn't mean total failure if you go outside of those parameters. If you don't overheat, and don't shock the yeast by a large temperature difference with your wort, the yeast will dig in and get right to work. Yeast is tough and adaptable.

 

[brewbama]

I'm sure the temperature range Lallemand specifies was determined to be optimum. That doesn't mean total failure if you go outside of those parameters. If you don't overheat, and don't shock the yeast by a large temperature difference with your wort, the yeast will dig in and get right to work. Yeast is tough and adaptable.

+1. Biology is a bit more messy than linearly switching on at this temp and switching off at that temp. It’s more fade in/fade out at a range of temps.

 

[Druman07]

Since i started rehydrating my yeast i have noticed faster starting of fermentation, and better attenuation, so I always do it before pitching now.

 

[jlietzow]

Thanks for the feedback everyone. So it sounds like I can start with sterilized water at the higher end of the preferred temps and just let it sit (not apply any more heat). If it gets below the preferred temp range then that's still preferable to firing up a burner to reheat (with the associated risk of stressing the yeast). That sounds a lot easier than I was making it!

Did I get that right?

 

[kh54s10]

I just use tap water. Get the right temperature to start. Sprinkle on the yeast, wait a while, stir in the yeast that is still dry, wait a while, pitch.

I don't worry about the temperature dropping.

I almost always have it starting by the next morning so before 10 hours. Once it took until afternoon so still less than 24 hours.

BTW, if you look on websites, I have found rehydration instructions on all the dry yeast sites I have looked at.

 

[jlietzow]

I found the Lallemand directions much less helpful than most. For example:

Attemperate in steps at 5-minute intervals of 10°C to the temperature of the wort by mixing aliquots of wort. Do not allow attemperation to be carried out by natural heat loss. This will take too long and could result in loss of viability or vitality.

Seriously - what in the heck is an "aliquot"? Were they just trying to be difficult? Nonetheless I think I get the gist of this now. Like most things in brewing, I'm sure this will become second nature before long.

 

[BongoYodeler]

I found the Lallemand directions much less helpful than most. For example:



Seriously - what in the heck is an "aliquot"? Were they just trying to be difficult? Nonetheless I think I get the gist of this now. Like most things in brewing, I'm sure this will become second nature before long.

Rather than putting it back on the heat source I think it might be better/easier to simply insulate the vessel to minimize heat loss.