spenghali

Recipes 

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.

MalFet

Recipes 

Much to the chagrin of lab drones everywhere, sadly there is not.

__________________
"Be excellent to each other." -Benjamin Franklin

spenghali

Recipes 

I thought not...alas Christmas is near...

MalFet

Recipes 

On the flip side, thanks to the massive cuts in basic science research these last few years, there are some amazing deals to be had on high-end microscopes on eBay. Good luck! I don't bust mine out too often anymore, but it's a lot of fun.

__________________
"Be excellent to each other." -Benjamin Franklin

TNGabe

Recipes 

Don't do it. Once you cross that line, there is no coming back. No longer a mere beer nerd, he's a nerd with a microscope! Watch out! If I'd have known how 'sciencey' making beer was, I'd have killed less brain cells in school.

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Give a man a beer, he'll drink for a day. Teach a man to brew, he'll drink for a lifetime.

Obliviousbrew

Recipes 

See now I want a microscope...

ajdelange

Recipes 

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.

MalFet

Recipes 

I've never used a nephelometer, but I have used a spectrophotometer. How would you calibrate them if not with a microscope and hemocytometer? Plus, wouldn't recipe formulation and idiosyncratic brewhouse parameters make calibration a moving target?

__________________
"Be excellent to each other." -Benjamin Franklin

passedpawn

Recipes 

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.

__________________
Now there's some take delight in the carriages a rolling
and others take delight in the hurling and the bowling
but I take delight in the juice of the barley
and courting pretty fair maids in the morning bright and early

ajdelange

Recipes 

That's how I would do it (because I have a 'scope and hemacytometer) but you could use any particle counting system you trusted. It would be the same concept as in using a refractometer for measuring alcohol. You would develop calibration curves for individual beers in your portfolio in the lab and then use the nephelometer in the brewery when brewing that beer for a much quicker check. I might be able to come up with a few general curves e.g. one for lager yeasts and one for ale yeasts, which you an others could use that would give an approximate count. How accurate would you have to be?