Yeast Starter

I will be making a yeast starter this weekend.  BeerSmith calls for a 2.0L size.  I will be using a stir plate.  Because of the 2.0L size I do not want the pitch the wort along with the yeast in the 5 gallon batch of beer.  I understand to let the yeast settle to the bottom and then I can decant the wort.  I read to put the yeast starter in a refrigerator to help the yeast settle to the bottom.  If this is true when can I pitch the yeast?  The yeast at this point will have a temperature of about 38 degrees.  Is this temperature a problem for the yeast?  Do I need to have the yeast at room temp to pitch it in the beer?

Cheers!!!!!

I usually build my starters several days in advance of the brews.  Depending upon the yeast being grown, I will allow the starter to stay on the stir plate for 24 to 36 hours then chill it in my refrigerator to around 42F for about 24 to 48 hours.  On brew day, I take the starter out of the refrigerator once I start the boil and decant as much of the starter wort as possible.  Once the boil is done and wort is chilling, I take my chilled sample that I used for measuring gravity and post boil pH and add it to the flask.  I swirl up the yeast to aerate it and then allow it to sit until it starts to develop a krausen (usually from 2 to 6 hours, again depending upon the yeast).  By then the wort is chilled, in the carboy, and at my starting fermentation temperature.  I pitch the yeast at that point.

Further points I have picked up which may also help: 

I always pitch at or below my fermentation temperature.  Since most of my fermentations start at the low end of the temperature range for the yeast I am using, I do not want to pitch warm and then chill, as it may cause the yeast to prematurely start flocculating. Warming the wort up a bit at the beginning of the fermentation is most suitable to their activity, since the fermentation produces heat.

It is better to pitch cold yeast into warmer wort.  The yeast will wake up more quickly with the more hospitable environment.

Most of the time these days, I am over building my starters and doing cell counts to divide up my yeast cake by volume for the next brew.  That way I know just what I pitched for cell count and can section off the remainder to grow up for the next brew.

Don't be afraid of a slight over pitch or under pitch, you will still get beer and the range for cell counts is pretty broad in my opinion.  Too large of a gap between your cell count and what is projected for the wort you are fermenting, especially on the low side,  and you may have more issues with off favors, stalling, poor clean up of byproducts of fermentation or lack of yeast character.

This is just my process and I am sure others have theirs which work just as well.

Thank You Oginme for the reply.  Excellent information.  I just looked in John Palmer's new book "How To Brew".  In the book there is a chapter on Yeast Management.  Your post falls in line with the book.  On page 122 John Palmer states "for large starters to chill the wort and then pour off the beer so only slurry will be pitched".  "You don't need to warm up the starter before pitching to your fermentor.  Pitching from Colder to Warmer helps wake up the yeast; it's pitching from Warmer to Colder that shocks them and puts them to sleep".

Cheers!!!

If you chill your starter in a refrigerator and decant off all the liquid, you will have a very hard time pitching the slurry when cold. It will be like peanut butter in the bottom of your container. I leave a little bit of liquid on top and let it sit on the counter to warm up during my mash and boil. Once it warms up a bit I swirl it vigorously to get all the yeast suspended in a liquid thin enough that I can pour it. I hadn't thought of adding my gravity samples instead of leaving liquid in the container. Great idea, Oginme!

--GF