Any reason I can't pitch washed yeast without making a starter?

[dachbach]

I've been reading washed yeast/starter threads for awhile and it seems that people in general recommend making a starter with washed yeast even if you have enough viable yeast to begin with. The reason I'm curious is that I don't brew that often and have no need for a bunch of mason jars of yeast sitting in my fridge forever.

I have three mason jars that each have about 2 oz of compacted slurry at the bottom. They've been in the fridge for almost 2 weeks. I'm going to brew again this weekend so they'll be right at 2 weeks old.

Using the default thickness and non-yeast percentage on Mr. Malty tells me I need 126 ml, which is 4.26 ounces.

Can I just decant most of the liquid off the three mason jars and pitch two full ones and a 1/4 of the last one?

Or is it really that necessary to make a starter first?

 

[shoreman]

As long as they smell alright go for it. I pitch non washed mason jar yeast all the time straight.

 

[CBMbrewer]

A starter will "wake up" the yeast and ensure that they are healthy before pitching. If you adjust the harvest date on mrmalty you'll see that if the yeast is old, there aren't as many viable healthy cells. I've heard that some people, if the yeast was harvested a week ago, just pitch that and have no issues. Any older then a few weeks and I would recommend a starter.

 

[brewkinger]

If 2 and 1/4 mason jars is equivalent to around 126 mL then it sounds like a plan.
Making a starter is best because it wakes the yeast up and prepares them for battle.
Not necessary though.

 

[dachbach]

So lets say I decided to make a starter. Would I use less than the 126 ml of slurry? Doesn't the starter make more yeast?

 

[jfolks]

I've been reading washed yeast/starter threads for awhile and it seems that people in general recommend making a starter with washed yeast even if you have enough viable yeast to begin with. The reason I'm curious is that I don't brew that often and have no need for a bunch of mason jars of yeast sitting in my fridge forever.

I have three mason jars that each have about 2 oz of compacted slurry at the bottom. They've been in the fridge for almost 2 weeks. I'm going to brew again this weekend so they'll be right at 2 weeks old.

Using the default thickness and non-yeast percentage on Mr. Malty tells me I need 126 ml, which is 4.26 ounces.

Can I just decant most of the liquid off the three mason jars and pitch two full ones and a 1/4 of the last one?

Or is it really that necessary to make a starter first?

According to some podcast I listened to from Jamil and John Palmer...

Harvested yeast is good for up to 2 weeks (in the fridge). After about a week, yeast begins to eat it's "reserves." Thus, if you wait more than a week from harvesting and pitching - you should make a starter to wake up the yeast and make more healthy cells. (you can get away with 3 weeks with some strains, but definitely make a starter if so)

To make a starter from harvested yeast, you need to figure out how much yeast you have. I like yeastcalc.com, but Mr Malty is good too. I find that my yeast slurries are typically in the 10-20% range. I suggest checking out this page from WYEAST: http://www.wyeastlab.com/com-yeast-harvest.cfm

Buy some WYEAST yeast nutrient and put it in another container - the container it comes in is identical to the containers used in the yeast slurry percentage chart. (Note: this is a relatively standard lab tube - they are available elsewhere I imagine). When you harvest your yeast, shake it up real good and fill the wyeast container with a sample (fill it to the top). Chill it overnight and the next day you can calculate how much yeast you have (using the chart on the wyeast page). For this reason, I like putting my yeast in a starter flask because it tells me how many ml I have of the entire starter.

wyeast says 40-60% slurry is 1.2 bil per ml. Mine is typically about 10% - if you cant measure your yeast, i would assume 10% as well. divide .10 by .50, and then times that by 1.2: ((.10/.50)*1.2). This gives us the actual number of cels per ml.

Using the billion cells per ml number, you can figure out how many ml you need to reach your desired cell count as calculated by mr malty or yeastcalc (# desired cells/observed cells per ml)


If you ever want to pitch recently harvested yeast (that doesn't need a starter)..

you divide your observed slurry percentage by .50 and multiply the result by 1.2 and multiply that result by the ml of your harvested yeast. (((.10/.50)*1.2)*ml)

This will give you the total cell count of your harvested yeast (in billions - so a result of 400 means 400 billion). Now you can use the previous formula (# desired cells/cells per ml) to find out how many ml you need to meet yeastcalc/mr malty's recommendation...no starter needed!

 

[dachbach]

Hey jfolks, thanks for the detailed answer. I have a question for you though. You say your slurry % is typically only 10%. So your calculations show that you only have .24 billion cells/ml. Mr. Malty's calc doesn't even have an option of anything less than 1 billion cells/ml. Are you sure you're calculating that correctly?

If I decant the liquid off my yeast, shouldn't I have a very thick yeast slurry (more in the 2-3 billion cells/ml range)? His default is 2.4. Obviously with the two week lag time the viability is less, but Mr. Malty's calc takes that into consideration.

 

[jfolks]

Hey jfolks, thanks for the detailed answer. I have a question for you though. You say your slurry % is typically only 10%. So your calculations show that you only have .24 billion cells/ml. Mr. Malty's calc doesn't even have an option of anything less than 1 billion cells/ml. Are you sure you're calculating that correctly?

If I decant the liquid off my yeast, shouldn't I have a very thick yeast slurry (more in the 2-3 billion cells/ml range)? His default is 2.4. Obviously with the two week lag time the viability is less, but Mr. Malty's calc takes that into consideration.

Yeah, Im sure. Im always amazed at how low my slurry percentage is...so i know what you mean.

That's why I suggested using yeastcalc to tell you how much yeast you need for X amount of wort at Y original gravity (not sure mr malty does that). This way, if yeastcalc says you need 200 bil cells for 5 gal of 1.057 wort, you can figure out how many ml (or cups) of your specific slurry you need to get 200 bil cells.

 

[jfolks]

or.. you can play around in yeastcalc to find out how many cells you could start with to make a starter that reaches the amount of cells you need. this way you can grow 100 into 200 etc.