I thought not...alas Christmas is near...
Is there a way to get an accurate cell count for pitching rates without the use of a microscope?
Yes, but they are probably not practical for the home brewer. Nephelometers and spectrophotometers can be used for cell counting as can various pieces of biomedical equipment which can, for example, distinguish and count RBCs and the various types of WBC's.
A nephelometer measures the amount of light scattered by yeast cells (and any other particle so trub, protein globs etc become a factor and a photometer measures light absorbed so that the color of the broth must be taken into account but once either instrument is calibrated it should be useable to the level of accuracy needed for this application.
Why count through inference when you can actually count?
Speed.
Why count through inference when you can actually count? I've seen these Amscope microscopes for sale cheap (~$200 or less?). Cell morphology isn't possible but simple counting certainly is. A capable hemocytometer can be bought new on Ebay for $30.
If time isn't an important factor, you could count CFUs using agar plates. But personally as much as I hate counting cells with a hemocytometer, I hate making serial dilutions, plating, and counting colonies even more.
There are good ImageJ macros out there for semi-automated cell counting. It works well as long as you don't have a lot of yeast-sized debris in your sample.
Agreed and Agreed.
Is counting CFU's more accurate than a hemocytometer? I've considered it, but wasn't sure if it would really be worth it. With the Hemocytometer you are diluting 20:1 or 40:1 but with plating is serial diluting to something on the order of 1E6:1
Is there a way to get an accurate cell count for pitching rates without the use of a microscope? I am looking for something other than a pitching rate calculator such as Mr. Malty.
Kai,
This is the first time I noticed your location. You're only about 40 minutes from where I work. Small world.
Cool. I'm in the Woburn area on a regular basis.
What I have noticed about Methylene Blue is that different strains take different amounts of dye to stain well. EC-1118 works well with equal parts 0.1% solution and diluted cells, while WLP566 stains fine with only one tenth of that concentration at 0.01%. If there is significant protein material it may take a little more stain as well. Normally I start with a 2:1 dilution of cells by 0.03% MB and if the dead cells are just a little bit blue I'll measure what is left in the test tube and add that much of 0.1% MB. This gives me a 4:1 dilution of about 0.06% MB. If you have too much MB the slide will look dark under the scope.
I have not played around with determining the reliability of MB staining or improving its accuracy. I'm citing from the literature sources and this is one of the charts I have come across in a German presentation from the Weihenstephan brewing school:
Why? If you're using fresh yeast and pitching the amount that Mr. Malty recommends, you really can't go wrong. I haven't heard anyone yet complain that it didn't produce good results. You could always pitch a little more than what Mr. Malty recommends if it's a concern. Do you want a microscope just to see how many are actually there?
I'm just curious as to why you're looking for something other than a pitching rate calculator.
Edit: After reading this, the tone didn't come through - I really am just curious. No disrespect intended....
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