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Old 09-11-2011, 07:53 AM   #1
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Apr 2011
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I've been reading up on "cropping" yeast. The only part that I'm not comfortable with is how to estimate how much yeast is in my slurry.

In the yeast book they mention, comparing a slurry to a known sample (like a vial of White Labs). I've also heard that you can measure the weight and use that to estimate.

I'm thinking that the only way to be sure is to buy a microscope. Does anyone use a microscope? If so, could you recommend a suitable model and how much I should expect to invest?

Does anyone have a creative way to count yeast without fancy tools?

 
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Old 09-11-2011, 08:31 AM   #2
Clementine
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May 2011
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We were just discussing this at this thread

http://www.homebrewtalk.com/f163/sla...g-time-267958/

To save retyping just read this, I assume after cropping you are making a starter so from there onward in your process it is the same as slants or any other method of making/reusing yeast.

Clem

 
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Old 09-11-2011, 09:19 AM   #3
_d_
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Apr 2011
Manhattan Beach, California
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Thanks for the link.

I'm not growing up from a slant, I'm harvesting the yeast cake, washing a little and re-pitching. I need a way to make sure I pitch the correct amount without making a new starter.

 
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Old 09-11-2011, 01:57 PM   #4
theonetrueruss
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Wite Labs has some info on cell counting: http://whitelabs.com/beer/CellCounting&Viability.pdf

I believe the only way to 'know' your cell count is to use a microscope setup. I hope to be able to do that one day though I think it's probably not necessary. I haven't pitched from slurry but If I did I think I would use Mr Malty's slurry calculator and estimate my slurry on the thin side.

 
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Old 09-11-2011, 02:08 PM   #5
MG1602
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Feb 2011
Richardson, Tx
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I work in a lab, and using a hemocytometer is the quickest way. A lot of technology out there for quick counts, but not cheap and definitely
not for home brew applications. Pretty easy to count once you understand your hemocyctomer. Get a cheap microscope on amazon for about 100
Bucks and buy the hemo for about 150. It is expensive, but it does what is suppose to do. Be careful, it is made of glass and will easily break!

 
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Old 09-11-2011, 03:20 PM   #6
Sardoman
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May 2010
Philadelphia
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I routinely use microscopes at work and have done a fair bit of yeast cell counting. I also culture my own yeast at home for brewing and I have used at least two of these cheap $100 amazon microscopes that I borrowed from friends. Neither I nor they think that those cheap microscopes were worth the investment because they work so poorly.

Here are some of the major drawbacks to those cheap microscopes. They tend to include some combination of the following:

-Flimsy mounting, so with any movement or vibration, the field of view shakes and you lose your place counting.
-Tiny field of view, so if you are not accustomed to using a microscope then you may have a difficult time finding the focal plane and you have to adjust the stage constantly while counting.
-Stage controls can be sloppy or tight, so you can easily lose your place on the slide/hemacytometer.
-Low quality lenses and mirrors, which make focusing difficult and can result in some parts of the field of view being in focus while other areas are out of focus.
-Uneven or Inadequately adjustable lighting, which makes it difficult to achieve the contrast you need to count cells that are not stained with any dye.

Although I have the luxury of taking my samples in to work to count them on a high-quality microscope, I don't bother. When you get the hang of culturing yeast you'll find a microscope is not necessary.

 
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Old 09-11-2011, 04:34 PM   #7
Patirck
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Apr 2010
Glendale, CA
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I just bought a usb microscope that plugs my pc. It works great so far and was $40.

http://www.amazon.com/gp/product/B0051ML8R6

Yes I can count yeast cells on it. I looked at the white labs doc and followed the instructions. I need to get a hemocytometer and the dye to do it properly but I can definitely see yeast cells quite well with it. I'm sure the traditional microscopes are much better but for $40 I figure it's good enough for me to count yeasties.

 
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Old 09-11-2011, 05:38 PM   #8
_d_
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Apr 2011
Manhattan Beach, California
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Would ebay be a good source? What kind of specs should I look for?

 
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Old 09-11-2011, 06:53 PM   #9
RiverCityBrewer
 
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I bought this microscope:

http://store.amscope.com/b100-ms.html

The pic is of WLP300 at 100x

I also bought a cheap hemacytometer on ebay for about $25... I doubt I would spend the cash to get a more expensive one because this one works fine.
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Old 09-11-2011, 07:07 PM   #10
MG1602
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Feb 2011
Richardson, Tx
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Nice scope! The cheap hemo you mentioned. Pretty reliable?

 
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