Yeast starter newbie, a few questions.

So I bought a couple of 2L Erlenmeyer Flasks so I can make some yeast starters. I'm tired of slow fermentation and hope this will help! I've got a couple of questions:

Do I need an airlock or will I be alright with just putting some foil over the top?

How can I calculate how much DME to use to get it to a certain gravity? I've read that 1.040 is "ideal" but I've also heard people saying that you should match the gravity of the beer it's going to be pitched in.

Should I put them in the fridge or do I want to ferment them at the same temperature that the beer will be fermenting at?

I'm planning on making the starters up a day or two in advance to give me a little bit of lead time.

Thanks in advance.

A yeast starter is a good idea. Foil IMHO is the way to go because it will let air get in there but keep the germies out. I wrap a rubber band around the foil after sanitizing it with Star San thoroughly. An airlock would be fine, but not necessary. 1.040 for gravity is good. You need 3/4 - 1 cup of DME per liter if I remember correctly. You'll want to ferment at room temp even if you're making a lager starter. Make sure to decant most of the liquid before pitching into your beer. Take the small amount of liquid that's left and mix it up with the slurry and bombs away!

I recommend the Brew Strong episode on yeast starters. It's very good!

http://thebrewingnetwork.com/shows/Brew-Strong/Brew-Strong-12-22-08-Yeast-Starters

I agree for the foil.

a 10:1 ratio of water to DME, (in grams), gives you 1.040. This means a 10:2 ratio gives you 1.080, a 10:1.5 ratio gives you 1.060, a 10:2.5 ratio gives you 1.100....I'm sure there's a formula in there somewhere.

Edit: ok, i'll make one up... for every 100 grams water, (or 100 mls water, since 1 ml = 1 gram), add (x-1.000)*250 grams of DME, where "x" is the desired SG. So if you want a 1.050 starter, for every 100 grams water you should add (1.050-1.000)*250 = 12.5 grams DME.

My starter method is ferment it warm, (not in my basement)....If you let it ferment at room temp, it will finish faster. Then I toss it in the fridge for a few hours to a day, and this cold crashes all the yeast to the bottom. I decant off most of the alcoholic wort, (can it be called beer if it doesn't have hops?), leaving me just with the yeast slurry that I pitch. I don't worry about it fermenting warm and developing off flavors because I dump all that gross, oxygenated, high temperature fermented beer out when I decant.

I like to keep it simple. For me, a yeast starter is 1/2 cup DME to 2 cups of water. I have a nice 2 cup measuring cup for the water, and a special little plastic 1/2 cup measuring cup for the DME. If I need a bigger starter, I just double those measurements.

Foil on the top is fine- you're growing yeast, and you want some oxygen in there.

For pitching, it's recommended to either pitch at high krausen, or wait until it ferments out and pitch it then. For lagers, I make the starter about a week in advance, stepping it up by adding fresh wort a couple of times. Then, I stick it in the fridge so that the yeast settles to the bottom, and only clear spent wort remains. I pour that off, and pitch only the yeast slurry into the lager.

For ales, I usually pitch the whole thing, since it's not that much.

You want the yeast starter to be roughly the same temperature as the wort that you're pitching into at the time. The starter is fine at room temperature- but then chill it to about the same temperature as the the wort so at pitching they are approximately the same temperature. If anything, I like to pitch the starter a bit cooler than the wort, no more than about 2 degrees. For example, for a lager, I'll pitch a 48 degree starter into a 50 degree wort.

Well damn, I was planning on brewing next Tuesday and Wednesday but I won't have my yeast until Monday. Would it screw things up if I brewed as usual and sealed up the beer and waited for the yeast starter to be ready? Or am I completely ruining the point of making a starter by doing that?

You do not need to wait. If you are starting with a vial of liquid yeast, and making 2L or less of a starter, yeast counts should reach their peak in 12-18 hours. (I found Mr.Malty's Yeast Starter FAQ very useful!)

Remember your goal is to get healthy, active yeast cells... so providing them with good food (wort), nutrients & oxygen is key.

A Stir Plate is a great way to go. It keeps the starter fresh with oxygen, allows other gases to escape, and keeps the yeast suspended.

Even if you just shake/swirl the flask every few hours, you will definitely increase your yeast count. So right there, you are better than just pitching the straight vial .. and previously that worked out fine too!

Good luck!
-LexusChris

bringing this one back from the dead for begginers