Stepped up starter vs. full volume

[haberlet]

Quick question-

I only own a 1 L flask and I usually get by with a starter that size. For the first time, I'm brewing a high gravity lager (1.075) and need a 2 L starter.

Is making a 1 L starter, decanting spent wort, and then adding another 900-1000 mL more or less effective than a straight 2 L starter?

Thanks,

-T

 

[m00ps]

That wont exactly be the same, but you should be fine. Do you have any growlers or other glass containers? I use growlers, cider jugs, and larger beer bottles as auxiliary starter vessels and split them off

 

[TheMadKing]

If you are using a stir plate, that should be just fine. I just used a 1.75L stir starter in a 1.09 beer and beersmith called it a 10% overpitch. If you don't have a stir plate, just shake it frequently, and the second step should get you right in the ballpark

 

[DurtyChemist]

When you pour off the beer you don't want make sure to keep about 100 mL in there. Swirl the yeast up and pour at least half into a sanitized mason jar. The inoculation rate will be better with less yeast. This means you'll grow MORE yeast than pitching the first starter directly into another 1L of wort. When you pitch into your beer pitch the mason jar and the flask. This is covered in the book Yeast if you haven't read that yet.

 

[brucebeernut]

On this same subject, I'm making a starter and overbuilding it to harvest the extra yeast. I'm starting with 1.076 OG ale recipe and want to harvest 220B cells, 2 "vials". Using Homebrew Dad's Online Yeast Starter Calculator, 1st step is a 1L starter (1.037) based on my yeast 57% viability. Says to use 101g DME (5.6oz). For the overbuild, it's at 2.5L to finish at 551B total cells. Pitch ~1.5L, harvest ~1L.
Newb question: How to do the second step? Do I pitch 1L 1st step into newly boiled DME (~250g/~8.9oz) for a 2.5L starter to end at 550B? Do I decant the 1L 1st step before pitching?
Help!

 

[RM-MN]

How do you know you need a 2 liter starter? Some of us are able to get a complete ferment with a much lower amount of yeast.

Yeast will reproduce to get enough cells if you give them the tools they need in your wort. Those tools are free amino nitrogen and oxygen. Your wort will have plenty of free amino nitrogen so you just need to add the oxygen. A good shaking will probably get you there, an airpump with an aeration stone will certainly do it, and pure oxygen is overkill for that beer.

 

[TheMadKing]

On this same subject, I'm making a starter and overbuilding it to harvest the extra yeast. I'm starting with 1.076 OG ale recipe and want to harvest 220B cells, 2 "vials". Using Homebrew Dad's Online Yeast Starter Calculator, 1st step is a 1L starter (1.037) based on my yeast 57% viability. Says to use 101g DME (5.6oz). For the overbuild, it's at 2.5L to finish at 551B total cells. Pitch ~1.5L, harvest ~1L.
Newb question: How to do the second step? Do I pitch 1L 1st step into newly boiled DME (~250g/~8.9oz) for a 2.5L starter to end at 550B? Do I decant the 1L 1st step before pitching?
Help!

Once the first step has been going for about 24 hours, stick it in the fridge for 48 hours. Then pour off all the extra wort and leave just enough to swirl all the built up yeast into a slurry. Let this warm to room temp and pitch it into a second 2.5L starter just like you did with the first one.

OR as stated above you'll get better cell multiplication if you pitch fewer cells into the second starter, so BEFORE you stick it in the fridge pour off 500 mL into a mason jar. That is one of your new "vials."

Now pitch the remaining yeast into a new 1.5L starter and repeat.

Just make sure you let your yeasts temperature change slowly (the speed of naturally sitting at room temp) otherwise you'll shock and stress them.

 

[TheMadKing]

How do you know you need a 2 liter starter? Some of us are able to get a complete ferment with a much lower amount of yeast.

Yeast will reproduce to get enough cells if you give them the tools they need in your wort. Those tools are free amino nitrogen and oxygen. Your wort will have plenty of free amino nitrogen so you just need to add the oxygen. A good shaking will probably get you there, an airpump with an aeration stone will certainly do it, and pure oxygen is overkill for that beer.

Yeast will multiply until they either run out of oxygen or nutrients (amino nitrogen and minerals). The more they have to multiply, the more nutrients will be used up in the lag phase and not in the fermentation phase.

The maximum possible concentration of oxygen you can get from the atmosphere is 8ppm. If you underpitch, your yeast sill multiply and your beer will likely ferment, however, overall yeast health sill be decreased because they are pushing the limits of the available oxygen when they have to spend more time budding and less time eating sugar.

Essentially you want to pitch enough cells that they only need to multiply between 2 and 4 times before reaching their maximum concentration (which I believe is about 1-2 million cells per mL but I cant remember)

Any more than that and you risk over crowding your beer. Any less than that and you risk stressing the yeast, creating thinner cell walls, and reducing yeast health which can create extra esters and phenols.

A starter isn't necessary, no, but it does ensure a healthy fermentation and a clean flavor profile.

 

[brucebeernut]

Once the first step has been going for about 24 hours, stick it in the fridge for 48 hours. Then pour off all the extra wort and leave just enough to swirl all the built up yeast into a slurry. Let this warm to room temp and pitch it into a second 2.5L starter just like you did with the first one.

OR as stated above you'll get better cell multiplication if you pitch fewer cells into the second starter, so BEFORE you stick it in the fridge pour off 500 mL into a mason jar. That is one of your new "vials."

Now pitch the remaining yeast into a new 1.5L starter and repeat.

Just make sure you let your yeasts temperature change slowly (the speed of naturally sitting at room temp) otherwise you'll shock and stress them.

Think I'll go this way... Pitch the decanted starter (~200b cells) into 2.5L with ~250g DME and put on my stir plate "Taz". Should end at ~550b. Pitch 1.5L (~330b) and harvest the remaining 1L (~220b). Schweeeet!