Stepping Up A Starter

[msjulian]

So you are referring to the point of diminishing growth?
A 4 liter starter on a stir plate will grow around 425 billion cells, which is about right for 6 gal of 1.050 lager. I've made a 2L starter with a lager yeast before and fermented at 50F, it ended up tasting fruity and it did not fully attenuate. All my subsequent lager fermentations have been great after following the calculator recommendations. You can probably go +/-20% from the calculator recommendation and be fine, but it is a good place to start.

That is correct. I think the comment on the show about the 20l starter was thrown out there as an exaggeration to make the point that the larger the starter didn't mean that the cell growth would go up at the same rate.

I might need a little more explanation on how to read your graph. What I am reading is that if you start out with 100 bil cells in a 1l starter would will end up with aprox 130 bil of new cell growth. How do you calculate that out to larger starters??

[brewcrew]

I am still having problems trying to figure this out. I am going to attempt my first lager (5.5 Gal at about 1.050) and would like to not run into any problems with under attenuation. If I use the Mr. Malty calc and Thirsty's recommendation it had me start with a 1L starter and then step up to a 3L starter. What do I do if my flask is only 2L? I am guessing splitting the 2nd step into 2 1.5L starters will not give me the same growth.

[BayouBrew]

I'd get a 1 gallon jug of crappy wine. Use the wine to romance a bus stop skank on V-day then use the jug for starters. You can't boil it on the stove like Pyrex, but other than that they work fine and are much cheaper than a 4L flask. You can also get a barbell stir rod to put it on a stir plate if you want.

[Nyakavt]

What I am reading is that if you start out with 100 bil cells in a 1l starter would will end up with aprox 130 bil of new cell growth. How do you calculate that out to larger starters??

That's correct, 100 billion cells into 1L of wort grows ~130 billion new cells. Your actual cell count is then the 100 billion that you started with + your 130 billion new growth, 230 billion. If you keep the same ratio of starting cell count to starter size, you can scale by just multiplying the result by your starter size. For example, if you start out with 200 billion cells and make a 2L starter, you will grow 130*2 = 260 billion new cells, for a total of 460 billion. Another example, if you start out with 100 billion cells and make a 4L starter your cell count ratio is 100/4 = 25. And that corresponds to ~80 billion new cells / L from the chart (you can plug your cell count ratio into the formula printed on the chart for a more exact number). So new growth will be 80 * 4 = 320 billion, for a total of 420 billion.

This chart is just a plot of what the mr. malty calcultor spits out, the important thing to remember is that in order to use the least amount of starter wort you want to stay around 1L/100 billion cells. For example, say you need 550 billion cells. You can make an 8L starter with 100 billion cells and be done. Alternatively, you can make a 1L starter (130 billion new cells, 230 after fermentation), then throw that into a 2.3 L starter (again sticking with the same ratio of 1L/100 billion cells) to get ~530 billion cells (230 starting + 2.3*130 new). So instead of using 8L of starter wort, you've grown almost as many cells using 3.3L. You can let the calculator do this for you by setting your viability to 230% and changing the gravity or volume until it says you need a 2.3L starter.

[Nyakavt]

I am still having problems trying to figure this out. I am going to attempt my first lager (5.5 Gal at about 1.050) and would like to not run into any problems with under attenuation. If I use the Mr. Malty calc and Thirsty's recommendation it had me start with a 1L starter and then step up to a 3L starter. What do I do if my flask is only 2L? I am guessing splitting the 2nd step into 2 1.5L starters will not give me the same growth.

5.5 gallons of lager at 1.050 requires 385 billion cells. Which tab are you using, intermittent shaking, stir plate, simple? The closest I can get to 3L after the 1st step is the simple starter, O2 at start option. After the first 1L starter you will have ~170 billion cells. Setting the viability to 170% gives you a 3.2L starter to grow enough yeast for this beer. You will get the same growth with 2X 1.6 liter starters if you split the starting yeast cell count in half (make sure the yeast is suspended evenly and pour off half the volume into a separate container. Each 1.6 L starter with 85 billion starting cells will grow to ~192 billion, and 192*2 = 384 billion, which is what you need.

[brewcrew]

5.5 gallons of lager at 1.050 requires 385 billion cells. Which tab are you using, intermittent shaking, stir plate, simple?

I used intermittent shaking. 84% Viability with a 1L starter gave me 140 billion cells for 5.5 gallons. If I used Thirsty's method and change the viability to 140 it says I need 3.2 L as my next step to get to the 385 billion cells. Am I not correct (actually we have pretty much the same results so I guess I am good)? So you are saying for my 2nd step I could either do the 3.2L or if I do not have a big enough flask, decant the 1L starter I made and evenly split into 2 1.6L starters? Based on the other dialogue and the chart would splitting anything over 2L into 2 starters get you into the ballpark as doing the 1 big starter (within reason)?

[Nyakavt]

I used intermittent shaking. 84% Viability with a 1L starter gave me 140 billion cells for 5.5 gallons. If I used Thirsty's method and change the viability to 140 it says I need 3.2 L as my next step to get to the 385 billion cells. Am I not correct (actually we have pretty much the same results so I guess I am good)?

That's it, the 84% viability threw me off. I still get a little bit better viability though, the calculator will spit out a large range of required cells before it says you need to jump above 1L. In other words, you are actually growing more cells in the 1L case than it tells you. What I do is change the volume until it says 1.01L, that's about the maximum you'll get out of a 1L starter. Try plugging in 84% viability, 2.5 gal, 1.050 OG lager on intermittent shaking. I get 175 billion cells. That means only a 2.4L starter for step 2.

So you are saying for my 2nd step I could either do the 3.2L or if I do not have a big enough flask, decant the 1L starter I made and evenly split into 2 1.6L starters? Based on the other dialogue and the chart would splitting anything over 2L into 2 starters get you into the ballpark as doing the 1 big starter (within reason)?

Yes that's right. If you keep the ratio of starting cell count to starter wort volume the same, the growth should scale up or down as much as you want. For example, a 1000mL starter with 100 billion cells is the same as 2X 500 mL starters with 50 billion cells each, which is the same as 10X 100 mL starters with 10 billion cells each. You just have to make sure that you have the same amount of yeast going in to each vessel when you split. At some point it is just easier to use the larger vessel.

[msjulian]

I just pitched my 4l starter into 6 gal of 1.050 Oktoberfest. Built the starter with 1 smack pack of Wyeast Bavarian Lager 2206 in 4l of 1.040 wort. It sat on the stir plate for 2.5 days and then into the fermentation fridge. After letting it settle out @ 36deg and decanting off the wort I ended up with about 300ml of creamy slurry. Warmed the yeast to 50deg and pitched. 24 hours later I have about a 1" layer of foam on top and the blow off tube is bubbling away. I just hope it has enough "umph" to finish up good and clean...