How do I make a Real Wort Starter?

Since I've recently switched to no-chill brewing, I ought to be able to make a Real Wort Starter (RWS) for my higher-gravity brews that call for a liquid yeast. How do I do it?

How much wort should I steal for the starter, if I have a 1L beaker? Should I dilute it to 1.040 if it's much higher than that to start with? Should I decant any wort off the top before pitching, or leave it in? Do I need to add yeast nutrient, since the wort obviously contains some?

Here's my suggested procedure; please correct anything you'd do differently.

1) When transferring the hot wort into the winpak, siphon less than 500 ml into the beaker.
2) Stir in 1 tsp yeast nutrient.
3) Cover loosely with foil and refrigerate to bring down to pitching temps.
4) Measure gravity, and add enough water (filtered? purified?) to bring to 500 ml and gravity of 1.040.
4) Pitch yeast, aerate, add stir bar and put it on the stirplate.
5) Wait 48 hours.
6) Decant wort and pitch the slurry into the now-cool aerated wort.

How does this look?

Why dilute it? I've not ever diluted my RWS, I believe you're prepping the yeasties for that particular brew with the RWS.

Yeah, but if that's the case, why don't you match the O.G. of a regular starter to the O.G. of the intended brew. Which I don't believe you're supposed to do. After all, "you're growing yeast, not making beer."

But it's good to hear you've been successful with full-strength RWS.

Anyone else care to weigh in?

why decant it? I thought one of the advantages of RWS is not having to decant (starter beer wont affect flavor of batch)

I think the issue is that since you are using a stir plate you have a lot of oxygen in the beer and you do not want to put that into your wort. You can taste it and see, but my understanding is that it will not be good. The main reason for the RWS is to get the yeast started and conditioned on the same wort that they will be eating once they get to the main beer. That is different than a DME starter where the yeast are started on DME which is different than the wort you then put them in too.

Ron

I just did a Maibock last night, and used a RWS. I just siphoned the first 2 gallons on top of the yeast I'll be using for the 10 gallon batch, its now in the fridge on the stirplate at 50F. I'll dump half of its entire contents into one of each of the carboys later this evening.
It's a 10 gallon 1.072 batch, so I used almost a full liter of slurry of WLP 830.
I did not dilute the wort in the RWS. The yeast is going very strong after 8 hours.
I do not know about "proper" RWS methods, I just did what makes sense for the yeast, from what I know.

rca said:

I think the issue is that since you are using a stir plate you have a lot of oxygen in the beer and you do not want to put that into your wort. You can taste it and see, but my understanding is that it will not be good. The main reason for the RWS is to get the yeast started and conditioned on the same wort that they will be eating once they get to the main beer. That is different than a DME starter where the yeast are started on DME which is different than the wort you then put them in too.

Ron

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I'm thinking that's not the case. After all, why would you aerate your wort (or pump oxygen into it) prior to pitching yeast?

PvtSkippy said:

I'm thinking that's not the case. After all, why would you aerate your wort (or pump oxygen into it) prior to pitching yeast?

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Yeah, but you don't aerate beer after you've pitched yeast. You'll be aerating a starter for much longer.

PvtSkippy said:

I'm thinking that's not the case. After all, why would you aerate your wort (or pump oxygen into it) prior to pitching yeast?

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That's basically what the stir plate is doing, constantly aerating your RWS. That's how it ferments out so quickly.

Ron

Synovia said:

Yeah, but you don't aerate beer after you've pitched yeast. You'll be aerating a starter for much longer.

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Actually, many folks do, especially on big beers.

I still don't an compelling reason to decant a RWS. Any oxygen in the starter would be absorbed by the yeast as they work to further increase in numbers. If you're talking about a two gallon starter into a five gallon batch, then yeah, that might be an issue but a one liter starter from a stir-plate shouldn't be an issue, IMO.

Understand I am not doing this yet, but I did ask The Pol about this in the no chill thread. I'm basing my answers on the discussion in that thread.

https://www.homebrewtalk.com/f13/exploring-no-chill-brewing-117111/index69.html#post1778954

Ron

Oh, thanks for the link to The Pol's explanation, Ron. I'd seen your question in that thread when you posted it but not his response!

Thanks for everyone's help!

rca said:

That's basically what the stir plate is doing, constantly aerating your RWS. That's how it ferments out so quickly.

Ron

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Only to the point where fermentation starts and the oxygen is displaced with co2.