Yeast Starter - the Growing Process

[klickcue]

1 pack (Wyeast 100 ml or White Labs 35 ml liquid yeast packages) yeast equals about 96 billion cells by the time you get or less.
96 billion cells will double in 1 liter of wort at 1.040 SG without aerating the wort which equals about 192 billion cells.

If you take the original 96 billion cells and add it to the same wort recipe as above but use a stir plate, you will get about 397.1 billion cells.

The interesting thing is that increasing your volume of starter wort doesn't increase the yeast that much.

With a 2 liter starter, you get 538 billion cells which is a delta of only 141 billion added cells added.

If your increase your starter to 3 liters you get 576 billion cells which is a delta of only 178 billion cells added.

So, it your saved about 15 ml slurry of your original 397 billion cells or about 250 ml of (1/4) of the original liter with the yeast in suspension and started over with 96 billion, you would end up with 794 billion cells with just 2 liters of wort. You have saved 1/3 the cost of the DME with just a few more hours on the stir plate. (2 liters of wort versus 3 liters of wort). That is a delta of 218 billion cells of 2 liters of wort compared to 3 liters of wort.

Now let us assume that you are brewing a 6 gallon batch of ale at 1.047 SG (198 billion cell needed). You really only need about ½ liter of wort for a starter on a stir plate with one package of yeast. So do a 1 liter starter (397 billion cells) and pour off 500 ml of yeast in suspension and save it in a sanitized jar and put it the refrigerator.. You have your next starter.

Hope that I did my math right and you can understand the steps.

By the way, you do not need the great tornado vortex that see in the videos of people stirring water to grow yeast. All you need is a slight vortex on top of the spinning wort, the O2 absorption occurs on the total surface area of the wort, so don’t fill your flask too full. Where power of the stir plate comes into play or sometimes more importantly getting the stir bar to connect is that as yeast multiply, the viscosity increases.

Have fun growing yeast and save yourself some money along the way.

[Jensen]

Great post Chris! I find that I go through quite a bit of Starter media in my process. I have always felt a minimum of 2 liter starter is needed, to not only activate cells, but to actually grow more...you have me thinking-- and saving in some starter juice in upcoming batches!

[klickcue]

Thanks!

All I try to do is make it cheaper for all of us, that way we can support the kids or buy toys. (Let along, the most important part is to brew more beer )

I find it interesting.

So, last night, I started with a 1 liter starter solution of 100 grams DME/1 liter of H2O and 96 billions cells of yeast. (397 billion yeast cells, ending)

Tonight (24 hours), I pulled the solution off the stir plate and poured off 750ml of of yeast in suspension to the refrig.. This left me with 250ml of yeast in suspension (another vial of yeast).

The 250 ml solution was added to 1 liter of 100 grams DME/1 liter of H2O.,

I don't need this much yeast, but may take it to 4 liter of wort starter for fun.

All so interesting. Look at the cost savings?

[klickcue]

Tonight, I am doing a 250 ml yeast in suspension starter from the last batch. I poured off 1 liter for from previous batch. This will be batch 3 or now using 3 liters total.

I have made some corrections to the original post, all in italics.

There were some private messages about yeast growth and growing yeast so I am answering them here:

To grow yeast, the first source that I used was this; which is Maribeth Raines excellent article on yeast http://www.maltosefalcons.com/tech/yeas ... -practices

Yeast curves and wort usage. If you have the book 'Yeast' by Chris White with Jamil Zainaheff (I believe the LBG library may have this book), on pages 140 and 141 shows the yeast yields and wort usage for not aerated yeast.

Yeast Calculators:
The first on the web with this, which became the web's most sourced link was this one:
http://www.mrmalty.com/ which leads to the calculator http://www.mrmalty.com/calc/calc.html

If you own a copy of Beersmith2 by Brad Smith, PhD, it has excellent tools for yeast propagation:
http://www.beersmith.com/

[klickcue]

Great post Chris! I find that I go through quite a bit of Starter media in my process. I have always felt a minimum of 2 liter starter is needed, to not only activate cells, but to actually grow more...you have me thinking-- and saving in some starter juice in upcoming batches!

In your process, I think to you do 10-12 gallon batches, 2 liters of starter would be very close for what you need per batch. At least your 2 liters could be on the stir plate for a single session instead of running two batches.

I think that you have the new Beersmith2 version, go in and play with the yeast tools.

[klickcue]

Great post Chris! I find that I go through quite a bit of Starter media in my process. I have always felt a minimum of 2 liter starter is needed, to not only activate cells, but to actually grow more...you have me thinking-- and saving in some starter juice in upcoming batches!

In your process, I think to you do 10-12 gallon batches, 2 liters of starter would be very close for what you need per batch. At least your 2 liters could be on the stir plate for a single session instead of running two batches.

I think that you have the new Beersmith2 version, go in and play with the yeast tools.

Here Jeff,

Beersmith2 screen shot:

The estimated gravity for the beer is 1.054 SG at 12 gallons in the Design tab.


In the Yeast Starter tab notice yeast cells needed and down at the bottom, the recommended starter size.

Notice in the top right 1/3 of the screen is the yeast used. When I built the starter of 100 billion yeast cells it was 2/10/2012. Of course, my current yeast stock is newer than that so I double clicked the yeast and get the date of the tag on the yeast. Doing this, derates the viable yeast count and adjust the starter and count accordingly.

In Tools yeast is another yeast growing application. In this application you can figure whether the beer is Ale, Hybrid or Lager depending on the fermentation temperature.

[klickcue]

Here is another yeast calculator that I like to use:
http://www.yeastcalc.com/index.html

I am building up an old yeast starter so yeast calc is really nice since it does stepped starter solutions. I find it easier to use than the Wyeast stepped starter interface.