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Best Practices for Stepping Up a Starter

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bluesman:
As far as making starters is concerned. There's three stages. There's the growth stage , the fermentation stage , and the flocculation stage. After talking with White Labs, I'm starting to rethink my process. WL is a proponent of the following process:

1. prepare 1 quart of 1.04/1.03 starter wort.
2. pitch yeast at proper pitching temp.
3. Allow yeast growth for 24 hrs.
4. Add a 2nd qt of starter wort
5. Allow yeast to grow 24 hrs.
6. Decant wort leaving yeast and add another quart and so on...

I use Mr Malty to calculate my yeast requirements.

Basically what WL is saying is that you don't want the yeast to enter the rapid fermentation stage, you want the yeast to remain in the growth stage. This will enable the yeast to be the most viable for it's battle ahead.

As quoted from White Labs:

"A "starter" can be any volume of wort that you add yeast to before using it to make your beer.  The yeast get active in this smaller volume, usually for 1-2 days, and then can be added to 5 gallons of beer, or 10 gallons, or whatever size your brewing.  This can be a good way to "proof" the yeast, and also when making high gravity beers. White Labs recommends on their label to make a starter "if the gravity is over 1.070, if the yeast is past its "best before" date, or if a faster start is desired." 
Procedure: 
Make up a 1-2 pint wort, gravity ~1.040, hopped as normal.  Boil for 30 minutes, cool to room temperature. Pitch one vial, shake well and let sit for 1-2 days.  Little to no activity will be seen in the starter, since this is a very small volume compared to the quantity of yeast pitched.  The yeast in a starter may be done within a couple of hours. But a layer of yeast should be at the bottom after 1-2 days. The wort on top of the yeast can be either decanted of the top, or left in and pitched with the whole volume. Most pitch the whole volume, but if the starter gets to the point of 2 liters for 5 gallons, then we recommend decanting the wort off the yeast.
Typical Starter Volumes for 5 gallons:
To activate the yeast: 1 pint
To regenerate expired yeast (there will be living yeast in the package for ~1 year): 2 pints
To brew a high gravity beer: 2 pints
To brew a lager beer, starting fermentation 50-55F: 4 pints"

Kaiser:
The best time to pitch yeast is when it is in the logarithmic phase. In brewing wort with and without oxygen yeast is always fermenting, so there is not really a phase where it is growing but not fermenting. There is however a stationary phase when the yeast stops growing because it ran out of nutrients (generally amino acids and/or sterols).

Pitching during the log growth phase may not be the most practical for all brewers. I, for example, like to use left over wort and heavily aerate it to grow yeast. This means I have to decant the wort and the only way to settle out lager yeast is by letting them finish. This is not ideal but good enough since the yeast will be fairly fresh.

Extract brewers can make "starters" from part of the beer ingredients (2-3 qt of the water for the batch and some extract. Then they pitch that 1 day before brewing the rest and reuniting it with that starter.

Kai

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