12 replies to this topic

[3rd party JKor]

I'm finally doing my first step up from one of my slants. I have a few WLP001s ready to go.I don't have a very good grasp on the way the cell count steps up through the use of successive starters. If I go with a slant into 100mL>1000mL>3000mL, is that giving me anywhere near what a vial into 3000mL will give me? I'm clueless here.

[3rd party JKor]

Just found this and I had to post it here. Care of Saccharomyces on HBT (with that name, how can you go wrong?):

Yeast reproduce to a certain concentration after which fermentation starts. The max concentration of yeast achieved is bound by the gravity of the wort, amount of available oxygen, and amount of available nutrients such as free nitrogen, zinc, or amino acids. Pitching without a starter may or may not yield the same number of yeast cells before fermentation begins depending on whether there is sufficient oxygen and nutrients available to support the number of generations that need to be produced. A starter with unlimited oxygen (eg. on a stir plate) and plenty of available nutrients presents ideal conditions for yeast growth, and should yield between 10M and 15M cells per mL/*P of wort. For a 1.040 wort and a 1L starter that means you would get 100B to 150B of cells regardless of the amount pitched into the starter. The drawback of starting from fewer cells is that you will have more generations, and each generation depending on the strain can take between 1 and 3 hours to reproduce. Longer lag times means a higher percentage of unwanted nasties will end up in the starter and eventually your beer, since these guys (bacteria) can reproduce as frequently as once every 15 minutes or so. Once fermentation begins bacteria growth in inhibited, and once alcohol concentration reaches 2% or greater most bacteria die. This is the main reason why it is recommended to only step up by a factor of 10 or so in cell counts. For instance, I'll pitch a slant (which probably has 1M viable cells on it) into 250mL of *sterile* wort on the stir plate, wait 24 hours, and then pitch that into 1-2L of wort on the stir plate. After 24 more hours my starter is ready to pitch into 5 gallons with 150B-300B active yeast cells. Wort doesn't present good conditions for yeast growth, unless you are making a 1.040 beer and you use an O2 stone to saturate the wort with oxygen before pitching. Even so I would still make a starter unless the yeast in question is very fresh, since yeast stored for long periods tends to have a long lag time increasing your chances of developing an unwanted infection. The recommended pitching rate is .75-1M cells/mL/*P for ales, and 1.5-2M cells/mL/*P for lagers. I typically aim for the upper end of the range for beers over 1.070 starting gravity, since the high sugar concentration both stresses the yeast and reduces the amount of oxygen I can introduce into the wort. Jamil's pitching calc (Mr Malty Pitching Rate Calculator) will give you the .75M or 1.5M numbers depending on whether you select ale or lager.

[ThroatwobblerMangrove]

Just found this and I had to post it here. Care of Saccharomyces on HBT (with that name, how can you go wrong?):

I'm just curious - do you have any pictures of a yeast slant with a frame of reference? I'm curious how big 1M viable cells looks like.

[MtnBrewer]

I'm just curious - do you have any pictures of a yeast slant with a frame of reference? I'm curious how big 1M viable cells looks like.

[3rd party JKor]

Here's one of my posts from when I made the slants. Mine have much more of angle on them. None of the pictures actually show the yeast growth. The surface of the slant looks pretty much exactly like the one MB posted.

[3rd party JKor]

I went with about 200mL in the first step. I think I'll go to 1000-1200 from there, then to 3,000. I'll go right from the 250 mL to the 1000 mL, then I'll chill and decant the spent wort when pitching to the 3000mL. Same when pitching to the batch.The nice thing about my canned starters is that they are crystal clear, no trub/break. As I step up it will be relatively easy to accurately measure the amount of yeast being generated. From that information, I should be able get a pretty good idea of how effectively the yeast is stepped up with this method.

[ThroatwobblerMangrove]

wow! I was a little worried that I hadn't saved enough yeast in one of my mason jars to make a full sized starter but now I know I'll be fine...

[3rd party JKor]

After I started my flask I was reading over MB Raines awesome page on yeast, she recommends going from the slant to 10mL, then stepping up to a bigger 500-1000mL volume. So, I might've tried to force too much propagation in the first step. The flask has a decent krausen on it right now, so it's working just fine. I'll step it up to 1000mL tonight and see where it goes.

[ncbeerbrewer]

I just sat down yesterday and this morning and started reading the Current Issue of BYO magazine. September 2009. There is a series of articles on Yeast and Fermentation. Yeast Biology by Chris ColbyYeast Handling by Gregg Doss (Wyeast Labs)Yeast Culturing by Chris White (White Labs)Yeast Metabolism by Chris White.They talk about starters and pitch rates and slanting yeast and culturing too, Great Articles as well. There is also an article about leaving your beer in primary for an extended period and any effects. Enjoy the issue, its a good one!!Mike

[3rd party JKor]

I just sat down yesterday and this morning and started reading the Current Issue of BYO magazine. September 2009. There is a series of articles on Yeast and Fermentation. Yeast Biology by Chris ColbyYeast Handling by Gregg Doss (Wyeast Labs)Yeast Culturing by Chris White (White Labs)Yeast Metabolism by Chris White.They talk about starters and pitch rates and slanting yeast and culturing too, Great Articles as well. There is also an article about leaving your beer in primary for an extended period and any effects. Enjoy the issue, its a good one!!Mike

I guess I'll have to pick that up.I pulled a sample from my initial step before I pitched it to the 1200 mL of sterile wort. After chilling overnight, I see about 3.8% yeast solids. Using WYeast's number, 40-60% solids = 1.2 billion cells/ml, I ended up with about 90 million cells/mL. For the 200mL step, that equates to a total cell count of about 18 billion cells.If I want to pitch .75 million cells/mL-°P, I need 378 billion for my batch. I've got 360 billion to go. It'll be interesting to see what the cell density is for the next size starter. I need to get it to 126 million cells/mL in the final step.

[ChefLamont]

I am behind on my reading of the recent articles, but the guy who recently taught me about culturing from slants takes one colony off the slant (or plate), puts it in a 10ml vial of wort, then to a 100ml, then to a 1000 ml, and then up from there as necessary. That is FWIW, just what I was told, but he seems to do well with it all.

[3rd party JKor]

I am behind on my reading of the recent articles, but the guy who recently taught me about culturing from slants takes one colony off the slant (or plate), puts it in a 10ml vial of wort, then to a 100ml, then to a 1000 ml, and then up from there as necessary. That is FWIW, just what I was told, but he seems to do well with it all.

It'll be interesting to see this step up turns out. Based on my very rough calculations the cell counts are coming up well. The 1200 mL starter had about 130 billion cells, if the cell concentration reaches the same level in the 3.2L starter I'll be around 300 billion. I'm a little shy of the 380 billion recommended rate.Of course, measuring yeast cells by volume is incredibly error prone. I'm using WYeast's recommendation from their website that the "pure" yeast slurry is approximately 2-3 billion cells/mL. Jamil's calculator allows you to assume that the pure slurry is up to 4.5 billion cells/mL. If my yeast concentration stays the same on this step I'll have about 126 mL of slurry, which would give me anywhere from 250 to 570 billion cells. Like I said, it's an error prone calculation.

[3rd party JKor]

I pitched my 3.2L starter to a 1.049 blond ale on Sunday. The starter had been in my fridge for two weeks, so I lost some viability, but it seemed to take off just fine. I decanted the spent wort and pitched the slurry cold into the well oxygenated wort. Wort temp was ~65-66°F. My controller is set for 67°F with 1°F hysteresis. Within a few hours I saw the first signs of fermentation, the next morning (T=~12hr) there was a thin Krausen (~1/4") and by early after noon (T=~18hr) there was a nice thick Krausen(>1"). I think the Krausen has remained pretty consistent since then, maybe it's grown a little.It looks like the propagation was fairly successful. I'll have to see how the beer ends up to know for sure. I'll probably wash and repitch this yeast for at least two more batches (assuming the beer tastes good), but the next time I go up from a starter I'll start at 10mL for the first propagation step.