[jeeyeop]

So I'm planning on brewing my first AG next week and I had some questions about the yeast starter.

Some info: I'm thinking of making an imperial stout with a gravity around 1.090-1.100. I'm going to make a small batch (~3 gallons). I also have the StirStarter with a 2L Erlenmeyer.

the MrMalty site recommends 1L + 1 pack/vial. Along with this I was going to use 1 cup of pale DME.

Sooo my questions (help with any is appreciated!):

-do the numbers that I have above look right?

-when I pitch the yeast, should I decant the liquid? I'm thinking the 1L extra pale wort might dilute the stout. I'm also wondering if there is a lot of yeast in the liquid portion if I decant.

-how many hours should I stir? If I will decant, how many hours in the fridge?

-it seems like the amount of water you use for the starter is important in the amount of cells you produce (aside from adding more yeast), would simply adding more water actually increase the cell count? What about more DME?

-do all liquid yeasts need nutrient or are there "fortified" yeasts at this point?

-I'll be treating my mash and sparge with ascorbic acid to drop out some chloramine, should I add a small proportional amount to my starter or will that be harmful/unnecessary?


Thanks again for any help!

[klickitat jim]

How set are you on imperial stout? That is a whole bag of special tricks in itself. You may have much greater success starting with a plain old American stout. That way you can learn all the basics first.

[RPIScotty]

That is quite a few questions. Some deeper research may be in order before you tackle a large RIS AND your first starter. I would think the "shaken, not stirred" starter method would work out for you. Try searching that or looking in the yeast and fermentation section for it. That, coupled with a good amount of oxygenation to the wort should work out good for you and be very simp,e to execute.

[klickitat jim]

I was going to ask if the stirplate had been used yet... I'd exchange it for an O2 reg and stainless wand.

[lenphallock]

Use 1 liter of water and 100 grams of DME. I'm not sure how that's measured in cups.

You can decant. Let it go on the stir plate for 18-24 hours. Put in fridge the morning of brew day for a couple of hours. Decant. Then pitch

Amount of water and DME matters because you want a starting gravity around 1.040. It's a nice round number that doesn't stress the yeast that much and encourages yeast growth.

Yeast should have nutrients even in the starter.

Should be dechlorinated water just like in your beer.

Good luck


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[narcout]

You will get varying opinions on this, but for high gravity beers like what you are proposing, I like to pitch close to the .75 million cells per milliliter per degree Plato metric.  That would put you in the vicinity of 200 billion cells for your 3 gallon batch.

I tend to make my starters around 1.040.  For a one liter starter, that would require 3.8 oz. of DME.

You could pitch the entire starter at high krausen; try to crash the starter at high krausen, wait for the yeast to sediment, decant, and pitch just the slurry; or wait until the starter has fermented out, crash, decant, and pitch just the slurry.  This is is also something you will get varying opinions about; you're going to have to make your own decision.

If you choose to decant, you will be able to see the liquid clear as the yeast begins to fall out of suspension.  I try to give the yeast two days to sediment, but I've decanted and pitched after 24 hours with good results.   

Yes, you can grow more yeast if you make a larger starter (and there is sufficient oxygen and nutrients).

I think it is a good idea to use yeast nutrient in starters. 

I don't know the answer to your question about chloramines as I typically decant my starters and don't worry about treating them.

Do you have a means of oxygenating or aerating your starter?  If so, you should use it.  If not, you can try the method of aerating by shaking (search "shaken not stirred" on this forum), but you'll want more headspace than you'll get with your 2 liter flask (a gallon glass jug would be better, and you can probably get one for a few bucks at the grocery store). 

You are also going to want to aerate or oxygenate your wort prior to (or just after) pitching the yeast.

[S. cerevisiae]

Ten percent weight by volume is the preferred solution when making a starter.  The solution should have a gravity of around 1.040, but DME is hygroscopic.   A 10% w/v 1L starter contains 100 grams (3.5 ounces) of truly dry DME. 

With that said, brewers should adopt the metric system when working with cultures.  The metric system is superior to the modified English units of measurement system that we use in the United States when performing laboratory work.  A milliliter of water weighs one gram.   A U.S. fluid ounce weighs more than a U.S. dry ounce.

If the OP is planning to make a Shaken, not stirred starter, he is going to need a larger vessel with a cylindrical shape that has a height to diameter ratio of no more than 2:1.  A glass one gallon jug will do the job. I primarily brew 3-gallon batches, and I would recommend a 1 liter starter made with 100 grams of DME and 1/4 tsp of yeast nutrient for an RIS.  The gravity of an RIS places osmotic pressure on the cells, and it is more difficult to dissolve O₂ in high gravity wort than it is low gravity wort, so one needs to start out with more cells.

In either case, I second Jim's suggestion to return the stir plate and purchase an O₂ wand, O₂ regulator, and an O₂ bottle.  A stir plate does not add much value to the equation.

OP Pitch the starter when it starter reaches high krausen, wort and all.