How do you know how many cells you have?

[wolfie7873]

If pitch-rate is important, and a starter is required (or you're using harvested yeast), how do you know how much yeast you're actually pitching? I've learned through experience that you *can* overpitch so I'm trying to figure out how to know how many cells are in a starter.

 

[Nosybear]

If you're doing a starter, overpitching is not likely. Basically, if I remember my read of the Brewing Elements book "Yeast," a single yeast starter will about double your initial number of cells. The initial number is not possible to determine unless you have a microscope and know how much liquid is in the vial/smack pack. At our scale, knowing exactly how many yeast cells we have isn't so important so I use the following rule of thumb: Less than 1.06, no starter (or a pint/half liter starter at most). More than 1.06, use a starter. I'm more likely to go to a liter starter for beers above 1.06 but that's just my preference. I get good results and that's mostly all I'm after.

 

[wolfie7873]

So is the purpose of the starter to multiply numbers *and* condition the yeast, or simply multiply their numbers? i.e., if a smack pack is for 5 gallons of wort, and I brew a 2 gallon batch of a "big" beer, would the smack pack without a starter work well?

 

[Ozarks Mountain Brewery]

the purpose of a starter is 1 to multiply the yeast, in most cases double the amount and 2 to wake up any dormant yeast thats been settled to the bottom

 

[Ozarks Mountain Brewery]

if you look on the yeast section of the recipe editor it will state the number of cells you need depending on the type of level your looking for, in most cases a single smack pack is 100 billion cells, here's some info

http://www.brewersfriend.com/yeast-pitc ... alculator/

https://www.wyeastlab.com/hb_productdet ... oductID=16

http://microbebrewer.blogspot.com/2014/ ... bilty.html

 

[SwampWater]

I have been using liquid yeast and have never received a vial/pac of yeast that had 100 billion cells. I guess being from Canada, we are just too far away from getting fresh yeast. No matter though, a starter to me is always required and with Brewers Friend starter calculator I get enough cells for my brews. A total guess though as far as numbers go and I never worry about it. Make a starter, brew and RDWAHAHB.

 

[Nosybear]

I have been using liquid yeast and have never received a vial/pac of yeast that had 100 billion cells. I guess being from Canada, we are just too far away from getting fresh yeast. No matter though, a starter to me is always required and with Brewers Friend starter calculator I get enough cells for my brews. A total guess though as far as numbers go and I never worry about it. Make a starter, brew and RDWAHAHB.

RDWHAHB, rinse, repeat.... You will never go wrong making a starter.

 

[wolfie7873]

OK, let's say I have harvested yeast from a previous batch. How do I know how much of IT to use on any given batch?

 

[Ozarks Mountain Brewery]

the general rule I go by is I use twice the amount as store bought yeast

 

[wolfie7873]

the general rule I go by is I use twice the amount as store bought yeast

As in twice the volume?

 

[Head First]

In order to re-use yeast there are a lot of different opinions.
Some say never, some say no more than 3 times, some say 9,but sanitation is the key for any yeast. What I do and has worked well for me is pitch first liquid yeast in a 5 gal batch without starter with wort under 1.06 gravity. I use a starter if bigger beer. I then save the yeast in a qt canning jar with the lid tightly sealed. Depending on the next beer gravity this is usually enough yeast for 2-5 gal batches. This will continue to multiply as you reuse.
As an experiment once I re-used 9 times. With the 9th batch some sort of super yeast infected and the FG of those batches were 1.002(this was 2- 5gal batches as I brew 10gal at a time). Pretty watery beer. No bad flavors but very watery alcoholic.
Not a very scientific answer but IMO saving and re-using yeast works well and to split the yeast to 2 batches does also. Never have overpitched doing this. Extreme sanitation is a must though. RHAHB and laugh if you do make a mistake.