Mead Lovers Digest #0222

Published in

· 8 months ago

 

Mead Lover's Digest #222                            Fri 08 October 1993 

 
        Forum for Discussion of Mead Brewing and Consuming 
               John Dilley, Digest Coordinator 

 
Contents: 
  Re: Yeast + Nutrient = Death? (Joyce Miller) 

 
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Date: Thu, 7 Oct 93 16:10:28 -0400 
From: jmiller@genome.wi.mit.edu (Joyce Miller) 
Subject: Re: Yeast + Nutrient = Death? 

>Hi. I made a small mead this weekend, but something funny happened to 
>the yeast. I hydrated it in a glass of warm water, with a half 
>teaspoon of "yeast nutrient" (no specifics on the label) in the glass. 
>The yeast wound up sitting there in the kitchen for at least an hour, 
>because there were complications in chilling the must. I pitched it 
>and waited for something to happen for about 36 hours. Since there was 
>no sign of activity, I just dumped another packet of yeast straight 
>into the fermentor. The mead took off a few hours later. 
> 
>So I'm wondering, did the yeast nutrient somehow kill the yeast? The 
>phrase "osmotic pressure" comes back to me from high school biology. . . . 
> 
>Jake. 

No, I'll bet the _water_ killed the yeast.  And osmotic shock was probably 
the cause.  Most yeast packets I've seen instruct you to hydrate the yeast 
in water briefly (like a few minutes), then add the starter solution 
(wort/must).  When a single-celled organism is placed in pure water, the 
water rushes through the cell wall & membrane in an effort to equalize the 
osmotic pressure -- basically, to dilute out the relatively high 
concentration of "stuff" on the other side (inside the cell).  It's one of 
those laws of nature & chemistry.  Now, most cell membranes contain "pumps" 
to keep that water out, but they can't withstand pure water for long.  The 
yeast nutrient probably allowed them to die less slowly (by somewhat 
equalizing the pressure by being dissolved "stuff" outside the cell), but 
couldn't save them.  All of your single-celled friends probably exploded.   

I just rehydrate mine in cooled wort. 

- -- Joyce 

 
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