mrmalty and wyeast lab calculators

[businesstime]

There seems (to me) to be some discrepancies between the two with regards to pitching rates. I wondered if anyone here could help explain what I'm missing.

Wyeast packs contain 100 billion cells, which claims to be able to innoculate 5 gallons of wort at 1.048 OG. Mrmalty acknowledges this in the FAQ section:

"According to both White Labs and Wyeast, a White Labs Pitchable Yeast vial and a Wyeast ACTIVATOR™ 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."

Yet, when you plug in those numbers into mrmalty's calculator (Ale, 1.048 OG, 5 gallons), it calculates that you need 168 billion cells. This is much more than the 100 billion figure!

 

[Beerrific]

He uses the rate quoted by many professional brewers: 0.75 million cells/ml/degPalto or 9 million cells/ml for a 12P wort. Roughly 170 billion for 5 gallons. (Double this for a lager.)

The 5.3 million/ml is not ideal but OK for a fresh pitch from the lab (as per the quote above). I think the problem is that you are never getting a pitch straight from the lab. The closest you can get to that is if you pick-up the yeast from the LHBS the day they get it in the mail.

 

[businesstime]

He uses the rate quoted by many professional brewers: 0.75 million cells/ml/degPalto or 9 million cells/ml for a 12P wort. Roughly 170 billion for 5 gallons. (Double this for a lager.)

The 5.3 million/ml is not ideal but OK for a fresh pitch from the lab (as per the quote above). I think the problem is that you are never getting a pitch straight from the lab. The closest you can get to that is if you pick-up the yeast from the LHBS the day they get it in the mail.

Thanks for the useful info!

Last night I created a 1 liter starter for a ~1.06 IPA I'm doing Saturday morning. From wyeast's lab site, that comes out to about 8.4 million cells/ml. Their chart is pretty vague and gives large ranges of values for what's appropriate, but it seems to be in the ballpark for a 1.06 OG ale.

Mrmalty's calculator works (sort of) in reverse of wyeasts in that it outputs my starter size instead for a 1.06 Ale. It tells me I need a starter size of 2.43 liters! That's a LOT bigger than my 1 liter starter. Moreover, that's a lot more unflavored beer I have to pour into my wonderful IPA wort if I choose to pitch at high krausen.

I'm starting to think I should grab another wyeast packet in addition to my starter, unless many of you think I will be OK with a 1 liter starter.

Thanks.

 

[beltbuckle]

You won't get much cell growth with a 100 billion cells placed into a 1L starter. Yeast have an sense of cell density and will not bud if the density is at a certain point. You will still do good having a 1L starter because you will start up the metabolism of the yeast and get them ready to go, but with a 2L+ starter recommended by Jamil's calculator, you will actually get the cell growth recommended.

 

[businesstime]

Do these calculators take into affect that adding the entire starter to the wort is going to drop it's OG already? i.e., if my calculations are right, then adding 0.5 gallons @1.040 to 5.25 gallons @ 1.06 will result in:

((5.25 * 1.06) + (0.50 * 1.04)) / 5.75 = 1.058 (new OG)

The bigger the starter the lower the OG will be, right?