Q: Ive heard that too small or too large a starter can be bad for the yeast. How is that possible?
Parker says putting a fresh vial of yeast into 500 ml of wort and letting such a small starter go to completion can actually leave the yeast less ready to ferment a batch of beer. The yeast do not rebuild their reserves and have very little increase in cell mass.
The minimum starter size for significant yeast growth from a vial or pack of yeast is 1 liter. One vial or pack into 1 liter results in approximately a 50% increase in cell mass.
Some brewers make a small starter volume (500 ml or less) with the sole intent of waking the yeast. When making small starters, it is best to pitch the entire volume at the height of activity.