Starter for Imperial Stout using washed yeast

[JHoward]

Hey everyone,
I know there are lots of topics on the subject of starters and washed yeast, but I this is my first experience with either of them so I want to make sure I do it right.

I'm going to be making an Imperial Stout with an OG of 1.096 and am going to be using some washed yeast (originally US-05). Should I use two vials of my washed yeast to make a starter for this beast? The yeast looks pretty much like the yeast on the right in the completed image of the illustrated yeast washing guide maybe with a little bit more in there.

Also, how big of a starter should I make? I was a little confused trying to use the slurry option on the MrMalty Yeast calculator.

I know I'm over-thinking this, but it being my first time with washed yeast, a starter, and a big beer, I'm a bit nervous.

Thanks!

 

[aseg]

I would make three - four quarts of a starter with one jar of washed yeast. If it seems sluggish, then add the other jar. I am assuming you are brewing 5 gallons too.

 

[JHoward]

Yes, I am brewing 5 gallons worth.


So, 3 quarts is just under 3 liters. That's a pretty big starter isn't it? How much DME should I use in a starter that big? 1.25 cups or so?

 

[Polboy]

I used 4 cups of US-05 cake from previous beer i bottled same day as i brew my 1.1SG RIS last Friday, according to MrMalty i over pitched by 5 times. I had active fermentation after 4h after pitching and lots of CO2 escaping through blow off tube for 4 days (at 24h time point there was no bubbles but continuous stream of co2) but yeasts stay in the bucket, everything stooped yesterday but i didnt check gravity yet. For beer like that i prefere to add too much than too little so go for a big starter (in your case it should be 7qt according to MrMalty again)

 

[aseg]

The rule of thumb I use for starters is 6 oz DME per 2 qts of water, or if you like metric 1 g DME to 10 ml. *Note water amounts are FINAL volumes.

1.096 is a big beer, and I am assuming that because it is an RIS, that it will have plenty of crystal/unfermentables. I don't typically put a lot of effort into determining the correct starter size, so in your case with this being your first time with washed yeast, I aimed high.

I have under-pitched before, but have yet to over-pitch, and I don't think that 3 qts is too much.

 

[JHoward]

Thank you very much, this really helps me out and makes me less nervous. I've wanted to brew an RIS for quite a while, so I'm extremely excited about this beer and just want to eliminate as many areas for failure as possible.

 

[wolverinebrewer]

Mr. Malty works but you need to know the harvest (washed) date.
I went to the Mr. Malty yeast calculator. For a 1.096 beer, it says you need 324 billion cells or approx. 158 mL. of yeast slurry which is just under 3/4 cup. This is only true if the slurry was harvested today. Since you said it was washed sometime in the past, you would need to input the harvest date and then proceed accordingly. For instance, I moved the harvest date to Nov. 1 and it says you need 324 mL., double the amount. So its really going to depend on how old your yeast sample is.
I use washed yeast almost always and I try to estimate the milliliter quantity in my pint jars then use as many jars as needed to get the number Mr Malty figures.
I would suggest getting to know how to use this calculator especially if you are going to do large beers often.

 

[JHoward]

Thanks for the reply wolverinebrewer. I harvested it on 11/19, so it's still pretty fresh. I think my problem with the Mr Malty calculator was trying to figure out what to choose for the yeast concentration and non yeast percentage.

So, if I get that amount of the packed yeast from the bottom of the jars of washed yeast, do I still make a starter? I thought the starter would help the number of yeast multiply and therefore require less yeast to start.

Sorry for all the questions, I'm just very scientifically minded and like to understand exactly how things like this work. Is there a good place I can read up on this more?

 

[wolverinebrewer]

Thanks for the reply wolverinebrewer. I harvested it on 11/19, so it's still pretty fresh. I think my problem with the Mr Malty calculator was trying to figure out what to choose for the yeast concentration and non yeast percentage.

So, if I get that amount of the packed yeast from the bottom of the jars of washed yeast, do I still make a starter? I thought the starter would help the number of yeast multiply and therefore require less yeast to start.

I think the yeast amount all depends on how good you washed it. If you did a bad job and still have a lot of trub in there, you should be able to see it. For me it is usually greenish. If it is clean, just estimate the mL. quantity and then use Malty to figure out how much you need. If you have trub then you need to estimate that percentage. Depending on these factors, you can use multiple jars of slurry to get to your desired amount or use less jars and make a starter to grow new yeast. Either way, I always decant the liquid in the sample jars and bring to room temp before pitching or I decant the starter liquid before pitching if I chose the starter route.
Harvested on the 19th, you need about 200 mL. which is still under a cup. Depending on your quantity in the jar, I'd probably just use as many jars to get to 1/2 cup of slurry and make a starter.
I'm only a 20+ batch brewer so my way might not be the best but I always get good attenuation so I keep doing it this way. Maybe a more knowledgable brewer can give you better info if I haven't been much help.