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-   -   yeast viability (http://www.homebrewtalk.com/f163/yeast-viability-349427/)

peter78 08-23-2012 05:39 AM

yeast viability
 
I got a WLP 001 vial with a best before date Nov-18-2012. From what I find in threads here, yeast is good for 6 months. Does that mean that my yeast was made on May 18th? I'm trying to figure out the starter size I need to make. Brewing on Saturday :rockin:

Aspenextreme 08-23-2012 01:11 PM

Make a starter with a stir plate and you will know if it is viable.

Brulosopher 08-23-2012 01:19 PM

Quote:

Originally Posted by peter78
I got a WLP 001 vial with a best before date Nov-18-2012. From what I find in threads here, yeast is good for 6 months. Does that mean that my yeast was made on May 18th? I'm trying to figure out the starter size I need to make. Brewing on Saturday :rockin:

Yep! For Wyeast, I believe they give a "manufactured on" date. Cheers!

peter78 08-23-2012 02:21 PM

It's White Labs and there's no manufactered date on it. Only expiration date. And I made a starter 7 hours ago, but I don't see any krausening or smell that yeasty smell. It's on the stir plate.

kh54s10 08-23-2012 02:23 PM

I may be wrong, but for White Labs, I think the manufacture date is 4 months before the best used by date.

Plug that into the calculators to determine the proper size for your starter.

zebbielm12 08-23-2012 02:27 PM

Read the label. It says the yeast is produced 4 months before the "best buy" date.

kh54s10 08-23-2012 02:29 PM

Quote:

Originally Posted by peter78 (Post 4354625)
It's White Labs and there's no manufactered date on it. Only expiration date. And I made a starter 7 hours ago, but I don't see any krausening or smell that yeasty smell. It's on the stir plate.

Get a flashlight and look really close. Do you see any tiny bubbles rising through the wort?

Sometimes you will not get any krausen at all. I also look for a color change.

I had one go off overnight and never saw anything, I chilled it and had a good layer of yeast on the bottom of the flask.

rhamilton 08-23-2012 02:32 PM

Quote:

Originally Posted by peter78 (Post 4354625)
It's White Labs and there's no manufactered date on it. Only expiration date. And I made a starter 7 hours ago, but I don't see any krausening or smell that yeasty smell. It's on the stir plate.

I've made some starters with White Lab cultures that were well past their best by date and I've noticed this phenomenon. You won't have krausen or have much in terms of visible fermentation but the yeast is indeed active. I stop my stir plate, wait a few hours, and look at the bottom of the starter vessel and look for the packed yeast at the bottom. It'll look like extremely fine sand but that is the active yeast.

peter78 08-23-2012 02:32 PM

1 Attachment(s)
I did plug it and it showed that the yeast is only 30% viable if it has been manufactured in May. I have to make a 2 step starter at 1.2L each. I'm doing the first one right now, but how do I know if it is active.

Attachment 72873

peter78 08-23-2012 02:40 PM

Ok. It does say that best before date is 4 months after bottling. Where was I looking... Now that's much better when I plug the numbers in the calculator.


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