Mr. Malty underpitch?

I do, almost always.

 

Strange. I've always found MrMalty to be very conservative (biiiig starters and/or more than a few packets/vials of yeast)

 

Apparently the ‘issue’ is that the Mr. Malty yeast calculator use a very conservative pitch rate of 0.75 million/ml/Plato vs. the ultra conservative pitch rate of 1.0 million/ml/Plato (see below).

“That's because they suggest 1.0 million/ml/Plato for gravities over 1.060. If I use the 0.75 million/ml/Plato option then I get the same result as Mr. Malty.”

If you are pitching fresh yeast vs. re-pitched yeast the appropriate pitch rate is 0.35 million/ml/Plato.

Cheers!

 

That's certainly appropriate in the sense that a 0.35 pitch rate is one valid choice among a fairly wide range of valid choices.

 

From the Mr. Malty FAQ:

“According to both White Labs and Wyeast, a White Labs Pitchable Yeast vial and a Wyeast ACTIVATORTM 125 XL Smack Pack both contain an average of 100 billion cells and are enough to pitch directly into 5 US gallons (18.9 liters) of an ale wort at 1.048 SG (12°P). This is a pitching rate of 5.3 million cells per milliliter, which is close to the pitching rate many professional breweries begin with when starting a new pitch of ale yeast. This rate works well because the health and vitality of fresh laboratory cultured yeast are superior to yeast harvested from normal fermentation.”

For a 15 Plato (Specific Gravity 1.061) wort the 5.3 million cells per milliliter ‘translates’ to 0.35 million cells/ml/Plato.

Cheers!

 

I think you would be more than fine with the Mr. Malty calculations (assuming your wort also has a proper amount of oxygen), 3 liters worth of starter is a pretty good amount even at 1098. Either way, I would suggest crashing your starters...that's a lot of stale beer being pitched with your yeast otherwise.

 

But why quote a 'preferred' cells per ml number (if that's your point) for 1.048 SG, and then apply that same number of cells to 1.061 SG, and say that the resulting cells/ml/Plato is also preferred?

 

The yeast calculator on the Brewers Friend website has a pulldown where you can select your preferred pitch rate; it includes the pitch rate of 0.35 million cells/ml/Plato.

http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

If an individual is brewing an ale with an OG less than 1.060 then they could certainly pitch less than the full amount of the smack pack/vial but I certainly would not suggest that. Since you bought the whole smack pack/vial you might as well use it.

Cheers!

 

From a 2006 article in BYO magazine:

“Wyeast’s 125 mL Activator packs are advertised to contain 100 billion cells, but actually average around 120–130 billion cells, according to Les Perkins, microbiologist and quality control manager for Wyeast.”

The various yeast calculators are very conservative in assuming a lower number of yeast cells in a fresh pack of liquid yeast. For example, the Mr. Malty yeast calculator assumes that a fresh liquid yeast pack (a package produced today) has 97 billion yeast cells. So, if you are using a fresh Wyeast Activator pack the yeast calculator is starting off with a value that is 24-34% lower.

Cheers!

 

Unless you count the cells, you are just making a SWAG as to what you are pitching. I do get good results with Mrmalty or Yeastcalc, so I don't see the need to invest in a microscope and hemocytometer. I have to draw the geek factor line somewhere.

 

Given the wildly diverse practices followed by contributors to this forum, and the almost nonexistent tales of woe resulting from over or under pitching, I think it's safe to say that the 'correct' pitch rate is a mighty wide range. The various calculators evidently make the assumption that over pitching is less problematic than under pitching.

 

“The various calculators evidently make the assumption that over pitching is less problematic than under pitching.” Amen to that!

Cheers!