The million-dollar question about yeast starters

[fab80]

This is a picture of two jars containing both the same washed yeast from a batch I brewed with wlp007. I got 4 pint-jars out of the yeast cake. These are the two jars containing the most amount of yeast and the one containing the least amount of yeast. Now, I know you should (must) make a starter with that washed yeast. But let's say I need to have a 2qt starter for my beer, how would using the yeast from one jar compared to the other one be different?

 

[WoodlandBrew]

If I answer the question do I really get a million dollars?

Cell density is roughly 2 billion cell per milliliter for settled yeast slurry. You can use that to figure out how many cells you are starting with. Alternatively, you could use a cell density meter or hemocytometer to get a better estimate:


http://www.woodlandbrew.com/2012/11/counting-yeast-cells-to-asses-viability.html
http://www.woodlandbrew.com/2014/07/cell-density-meter.html

Once you know how many you have, you can figure out how many you need and how to get there with a number of calculators. Here is one that shows growth over time:
http://www.woodlandbrew.com/2015/02/starter-calculator.html

The answer to you question in a nut shell is more DME will be needed to produce more growth when starting with less yeast. It will also take more time.

 

[eadavis80]

Take this for what it's worth. When I harvest/wash, I almost always end right around 25 ML of niece yeast at the bottom of my mason jar. I make a 650 ML water with 1/2 cup of DME a few days before pitching, if the harvested yeast is within 3 or less weeks old. If it's older than that, I might bump it up to a 2L starter with 1 cup of DME. Has worked fine for me.

 

[DurtyChemist]

You don't HAVE to do anything. You could pitch the jar with more yeast directly into your wort and it will ferment just fine. The difference between using jars is the one on the left might get stressed and give up without a starter while the one on the right might not.

Edit:do what biologists do when they want an answer, run an experiment using each jar on a separate batch of the same wort and monitor the results. Measure how much yeast a new pack of yeast gives volumetric ally with a 2L starter in your brewery and compare it to the volume o feast in the jar on the right.

 

[fab80]

Thank you all for the replies and the precious information woodlandbrew. DurtyChemist I have pitched the washed yeast (from a couple of jars) NO starter in a beer before with good results, but on a batch a while ago I used yeast that was more than 3 months old, and it took forever to start and even more to finish. Beer was not good either. Since then I decided I would only do starters when using washed yeast. I am just trying to figure out the most consistent way to do that....

 

[oogaboogachiefwalkingdeer]

Why even wash it? Just save the slurry and pitch about a half pint and your good to go. Might even be healthier than washed from what I have been reading. I know it is cheaper. For the dme starter price you can buy a new pack of dry yeast.

 

[Singletrack]

Once you know how many you have, you can figure out how many you need and how to get there with a number of calculators. Here is one that shows growth over time:
http://www.woodlandbrew.com/2015/02/starter-calculator.html

Nice calculator!

You mentioned that "a number of calculators" could be used. I noticed that the Woodland calculator gives results that are very different from one of the most popular calculators, which is the one I regularly use. The Woodland calculator predicts better yeast viability over the storage time. It also results in much smaller starters to achieve the cell count, even when starting from the same viability.

I have guessed that the Mr. calculator I use is conservative, but I reasoned that my starter techniques are less than ideal. As examples: I may leave the yeast on the stir plate too long while I'm away at work. I don't control starter temperature. I chill and decant, and this probably kills some yeast and wastes some down the drain. After decanting, my yeast may warm too much before pitching, or I may pitch cold yeast into 65 F wort. And I know I can't pour every cell out of the flask and into the wort. So... given my real world circumstances, should I make adjustments to the Woodland calculator to compensate, or am I just over-pitching by a significant margin? Or both?

Sorry if this is a little off topic.

 

[WoodlandBrew]

I don't want to tell anyone what to do, if what you are doing works, I don't want to suggest that you change what you are doing.

Measurements I have done on viability show much less loss that what Mr. Malty shows. If you are cold crashing and decanting you might be loosing 1%-5% of your cell count which will probably not have a significant impact on fermentation performance. I also would worry about letting the starter run a little long. Glycogen reserves are built up at the end of fermentation. This will help the cells start back up in the next fermentation. Viability drops at room temperature are actually pretty slow if the ABV level is reasonable. See here for details: http://www.woodlandbrew.com/2013/01/abv-effects-on-yeast.html
Propagate rate will change slightly with temperature, but there is very little impact on the yeast health assuming temperature is reasonable. (If you are comfortable, the yeast probably is too.)

 

[Singletrack]

I don't want to tell anyone what to do, if what you are doing works, I don't want to suggest that you change what you are doing.

I've been enjoying your web site. Thank you. I really was hoping you would say it's nuts to make such large starters, because I would like to cut back. So, I will gradually cut back and see what happens. Once I get it dialed in, look for the new Singletrack starter calculator. Ha!