Methylene blue to test yeast viability

[NotSure]

Hi all,
I'm new here and didn't find an answer on existing posts. Has anyone used methylene blue to check yeast viability? My understanding is that pro brewers use (or use to use) it to get a better handle on the number of live cells they're pitching. Or is it just not worth doing on a smaller scale?

Any insight is appreciated!
NS

 

[Vale71]

It's actually quite unreliable at any scale. You can have both dead cells that don't stain as well as live cells that still stain blue.
There are more accurate methods today that unfortunately are prohibitively expensive for homebrewers as well as for small scale breweries.

 

[NeoBrew]

I've got all the supplies and did it twice. I stocked up on a microscope and the few pieces needed to do it last year. I was all gung ho to get a yeast lab set up and add that to my brewing skills. I even banked some yeast and stored it.

It's not that hard. The biggest challenge for me was the measuring and math to determine how much to dilute the samples and multiply up the count you get. That is to say, not that hard. I followed the process in The Yeast Book by Jamil Zanishev

I do hope that I find the time to get back into it at some point. What I've found so far is that it's so much easier for me to just buy a new yeast packet and grow it up in a starter.

 

[passedpawn]

Hi all,
I'm new here and didn't find an answer on existing posts. Has anyone used methylene blue to check yeast viability? My understanding is that pro brewers use (or use to use) it to get a better handle on the number of live cells they're pitching. Or is it just not worth doing on a smaller scale?

Any insight is appreciated!
NS

Methylene Blue works fine for a pass/fail test. That is, if you're seeing mostly viable cells (> 90%) then you can trust it, and mostly dead you can also trust. For most homebrewers, that's good enough.

Though, as Vale said above, If you really want accurate numbers you're not going to get that. If the staining isn't definitive for your eyes, you might try another stain like crystal violet. I've used that and while I don't think it's any more accurate, it seems to give me better contrast between good cells and dead.

For my purposes, cell counting was the most interesting thing. And, checking for bacterial interlopers! After counting, I'd add a stain just to make sure they were mostly viable, which they always were.

 

[passedpawn]

I've got all the supplies and did it twice. I stocked up on a microscope and the few pieces needed to do it last year. I was all gung ho to get a yeast lab set up and add that to my brewing skills. I even banked some yeast and stored it.

It's not that hard. The biggest challenge for me was the measuring and math to determine how much to dilute the samples and multiply up the count you get. That is to say, not that hard. I followed the process in The Yeast Book by Jamil Zanishev

I do hope that I find the time to get back into it at some point. What I've found so far is that it's so much easier for me to just buy a new yeast packet and grow it up in a starter.

I made an excel spreadsheet to make the conversions easier when using a hemocytometer. It might not be intuitive at first, but if you play with it a few times you'll see how it works. I'll attach it here for anyone who wants to give it a whirl.

 

[NeoBrew]

I made an excel spreadsheet to make the conversions easier when using a hemocytometer. It might not be intuitive at first, but if you play with it a few times you'll see how it works. I'll attach it here for anyone who wants to give it a whirl.

Thank you!

 

[NotSure]

Thank you Vale, Neo and Passedpawn. You've given me a lot to think about. Very much appreciated.