jcaddy35

Recipes 

When calculating the amount of DME to use in the yeast starter, should I be using the beginning (pre-evaporation) amount of water, or the ending (post evaporation) amount?

For example:

If I want a 1 Liter yeast starter that has a gravity of 1.037, I would need to use 1.5 Liters in the pot to boil for 10-15 minutes. Therefore, I would need either 5.2 ounces of DME (which gives me 1.037 in 1.5 liters), or 3.5 ounces of DME (which gives me 1.036 in 1 liter). Which one is correct?

I'm guessing it's 3.5 ounces since the water evaporates, but not the DME. Am I correct here?

Bensiff

Recipes 

Pre...it makes life easy as starters aren't exacting so it doesn't much matter if you are off by 5 points. I use 1 gram DME/ 10ml water, add the DME and yeast nutrient into my flask, top up to desired level and boil.

WoodlandBrew

Recipes 

You are correct. Post boil is used to calculate gravity. Although you shouldn't have much boil off at all making a starter. You just need to get it to a boil and then cool.

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bobbrews

Recipes 

I always put the recommended starter amount in the actual beaker. So if it calls for 1 liters of starter and 1/2 cup DME, I make sure that volume is what's in my beaker in the end, not 750 ml after boiling evaporation. I don't think a couple points off your target starter OG will really matter, especially if you're only pitching a slurry and not the whole volume.