2 Starter Questions

[wittenbergdoor]

Hey Folks,

So I'm a pretty new brewer, and I'll be doing my first starter with my next batch next week. I will add .5 cups light DME to 2 cups water, plus some nutrient, and then I will add my yeast to my cooled flask and put it on my stir plate to maximize cell growth. Here are my questions:

1. Using a stir plate, how do I know when the starter is ready? I need to bring 1 vial of White Labs London Ale yeast up to 197 billion cells. Beersmith says I will achieve 237 billion, using a stir plate and a 1 liter starter (I assume the extra 40 billion cells will not be a problem?). But how long do I leave it on the plate for? I plan on putting it in the fridge about 12 hours before brewing to get the yeast to drop to the bottom.

2. What exactly do you do differently when making a 1 liter starter, vs. a 2 liter? If the recipe is the same, what determines the amount of starter you end up with? And to what does the liter measurement refer? I take it it is the amount of actual pitchable yeast?

Any help would be greatly appreciated.

 

[LLBeanJ]

Usually 24 hours on the stir plate will do it. As the cell count increases the wort color will change from a translucent brown to a milky brown. A lot of the times I'll get the starter going in the evening and by the next morning the starter has dramatically changed color, but just to be sure it's fermented out completely I will let it go a full 24 hours.

You don't really do anything differently when making larger starters. The process is the same. If your starter vessel is too small you'll have to cold crash and decant between steps to make room. The liter measurements refer to the total volume of water and DME. If you were doing a 1L starter, you would combine 100g DME + enough water to bring the total volume to 1.0L. This will yield 1L of 1.040 wort. To determine what size starter you need, you can use a yeast calculator, such as this one.

Edit: Also, when using that yeast calculator, when planning steps and using a stir plate, use the Kai Troester's method, as it's been verified as being closer to reality than Jamil's.