Dry Yeast Pitching Calculators - What do you use?

[Cervantes]

Been looking at several dry yeast pitching calculators and there seems to be quite a bit of variance between them, which seems to be due to differing views on the cell count per gram.

The extract below is from the Brewer's Friend website.

Dry Yeast - billions of cells per gram:

• No one agrees on the number of yeast cells per gram in dry yeast!
• This is made more confusing because each yeast strain has different size cells and clumping tendencies.
• We put in a reasonable default of 10 billion cells per gram of dry yeast.
• Kaiser located a study which reports the following data on dry yeast ranging from 8-18 billion cells per gram:
  
  Yeast
  
  B cells/g
  
  Safale K-97
  
  14
  
  Safale S-04
  
  8
  
  Safbrew T-58
  
  18
  
  Safbrew S-33
  
  16
  
  Saflager S-23
  
  10
  
  Saflager S-189
  
  9
  [SIZE=9pt]Adapted from: Van Den Berg, S., & Van Landschoot, A. (2003). Practical use of dried yeasts in the brewing industry. CEREVISIA, 28(3), 25-30 (Table 1). [/SIZE]
  
• Mr.Malty says that dry yeast contains 20 billion cells per gram. Unfortunately we could not find a reference to a study that supports that number.
• From the manufacturers:
  Fermentis: > 6B cells/gram for US-05 and S-04.
• Danstar: > 5B cells/gram for Nottingham yeast.
• These numbers sound conservative and do not match with the study referenced above. According to our pitching calculator, with dry yeast, using the mfg's number of 6B cells/g, to hit a pitch rate of 0.75 (M cells / ml / ° P) for a 5 gallon batch @1.050 would require 3x 11g packs!

[*]Link to a researcher claiming 20B, but only has an n of 1.
[*]Most dry yeast packs come in 5g or 11g amounts. With dry yeast, starters are typically not made because dry yeast is relatively cheap - just buy more packs to hit the target pitch rate.

So I'd like to know which pitching calculators you use for dried yeast and what sort of results you get.

According to the Brewer's Friend Calculator I've been seriously under pitching, but seem to get good results anyway. But could they be better?

Thanks in advance
Andy

 

[Cervantes]

Bump

 

[MHB]

It's bee an ongoing debate for years, and I suspect no closer to resolution.
Just looking at the linked sheet for US-05 (far and away the best selling yeast in Australia, probably the world), there are two different answers on the same sheet.

First it says 50-80g/hL so if we look at a 20L wort that's 10-16g/20L. One 11g pack being in that range, if at the lower end.

Second we have "Viable cells at packaging" 6*109/g (6e9 for ease of typing)
If you want 0.75e6/mL/oP in a 20l 1.050 (12.5oP) wort you need 0.75e6*20e3*12.5=187,500,000,000 (1.875e11) cells @ 6e9/g means 31.25g so yes about 3 of 11g packets.

Clearly from experience 1 packet will do the job, would 3 do the job a lot better - well maybe but not if you want much in the way of yeast flavour development, personally I would probably pitch 2 packets.
I think you need to take a long hard look at a few variables: -
The age of the yeast, young fresh yeast will have better viability.
The way the yeast is stored - my local has very fresh yeast kept refrigerated, still see old packets sitting on the shelf at some HBS's
How you manage your yeast, read the "rehydration" instructions - how closely does what you at doing conform to what Fermentis recommends are your procedures. I think a lot of home brewers kill half their yeast by following pretty crappy rehydration instructions.
Do you aerate/use O2 good aeration makes a big difference to not just how many live cells you have, but how "Vital" they are.

I suppose that we all will have to take a bit of a punt on how much to use, but there clearly isn't a single "RIGHT" answer, think through what you do, do a split brew or two with different amounts of yeast, see if you can notice any difference and whether or not the difference is worth the cost, in both time and effort and yeast.
Mark

 

[JDW81]

FWIW I use the Mr Malty calculator as a guide.

Is it accurate? I don't know, however when I use the numbers on the based on beer gravity and yeast viability I always get a good strong ferment and predictable attenuation.

 

[Cervantes]

Thanks for the replies.

I'm going to bump up to two packs next brew. I always rehydrate according to best practice and add O2 from a bottle, but will try adding an extra pack to see if it makes a difference.

My nearest decent supply of liquid yeast is a three hour drive away, so I'm generally always restricted to using dry yeast.

If I wanted to make a starter from dry yeast is the procedure the same as for liquid yeast?

 

[tavas]

1 pack per 23 litre batch for ales. 2 packs for lagers. I can't tell any difference between re-hydrating and dry pitching.

 

[Danscraftbeer]

I have more of a habit of over pitching than under pitching. Only slightly as possible.
Call it under pitching paranoia that is silly really because under pitching can sometimes get great results in flavour character. One of my best beers according to other tasters was underpitched in my records.

I use any/all the yeast calculators, observe and take an average. MrMalty. Beersmith. Brewers Friend, um others as well...
edit: Confirm package dates and postage scenarios to get a Viability percentage etc.

Paranoia? no.
Scientific? yes.

 

[Mr B]

Little off topic:

Any rationale as to why you shouldnt use say 2g of dry yeast to build up a starter/liquid pitch?

Can keep to the 5-10x rule etc.

 

[Cervantes]

Little off topic:

Any rationale as to why you shouldnt use say 2g of dry yeast to build up a starter/liquid pitch?

Can keep to the 5-10x rule etc.

I've been doing some reading on this and there is a lot of varied opinion on the interwebs.

I've personally decided against it for the time being, but the one piece of advice that I did take away from my reading, is that if you're going to make a starter using dry yeast you should rehydrate in water first.