Yeast Pitch Rate by Vial or Pack

[klickcue]

At times, I will wash and save my yeast from a batch of beer under sterilized water in a 1 liter soda pop container. The yeast in water is then dated with the yeast type and stored in the refrig.

It is a pain to get the yeast out of the container and still maintain a water cover.

I came up with this idea. Since a White Labs container is 35 ml and http://www.mrmalty.com/calc/calc.html uses tube or packages for pitching rate, work it backwards.

A White Labs tube that has sat vertical is about 30 to 50 percent yeast depending on the yeast cell size, the rest is food in water.

Pour off the water in the storage container until the water equals the packed yeast (1:1). Shake the yeast container to get the yeast back into suspension.

Go to Mr Malty and fill in the Type, SG, Volume and the Harvest Date (viability). Take the recommended vials without a starter and multiply by 35. Measure that many milliliters of the suspended yeast in a container.

Should get a person close on pitching rate.

[Blktre]

Where does the number 35 come from Chris?

[Travel by the Pint]

I started yeast ranching a few batches ago, so this post peaks my curiosity. So far the only time I've actually used harvested yeast, I was brewing 24 hours after racking, so I simply scooped up about 1/2 cup of trub, cleaned it as best I could with boiled/cooled water washes, then added it to a flask with some DME. This worked terrifically, btw.

But the next time I do this I'll be using yeast that's been washed and stored in the refrigerator for a month. I gather you're suggesting that I take only a measured portion of my harvest to add to my next batch?

[Jdl973]

Andy, I think the 35 is a factor for the % yeast in a vial of commercial yeast...30-50% of the total volume of liquid..., so 35% would be a low conservative number depending on the size of the yeast cells.

Is this right Chris?

Jason

[Jdl973]

It depends on the type of yeast strain you are using. Most Lager strains, you can over pitch without too many issues. With some of the ale strains, particularly the Belgian strains, this is not the case. With the Belgian beers, the yeast actually have a growth cycle in the wort which produces some of the flavor compounds, phenols, esters, higher alcohols and others. At low concentrations, they add flavor, but if you over pitch the yeast, it goes bonkers and 2 things can happen:

1 This raises your temperature dramatically, almost out of control. This is bad because if you try to rapidly cool down a Belgian yeast (just a couple of degrees) it will go into "survival"/dormant mode and will shut down. Nothing you can do will wake it...it is time to pitch a new batch of yeast.

2. The higher temp and growth rate will produce more of the trace compounds listed above, in small amounts they give the beer character, in large amounts it makes the beer taste like crap (bubblegum, banana, nail polish remover (Ethel acetate) and so on.

So, if you know your beer can handle a good solid dose of yeast (100-300 million/ml), just scoop away, rinse (most of the time I do not rinse, leave a little bit of wort over the cake and seal the top of the carboy, next brew day, pitch new wort right on the cake, shake the begezers out of it and off to the races) and pop in the fridge. At 35-45F, it should be good for about 6 months ( have have used slurry up to a year). If it starts to look like peanut butter and does not smell like yeast should, get rid of it.

The other trick to wash your yeast is to drop the pH to around 2.5. This will clean the yeast of the hydroscopic biproducts of fermentation and yeast growth. You should not have to do this if you put the yeast through 2-3 generations, but after that it is recommenced. There are food grade acids you can use to wash the yeast, then rinse the acid off with distilled water and bring the pH back in the 5.2 range with a buffer.

Jason

[klickcue]

35 comes from 35 ml in a White Labs vial.

So, if Mr Malty calls for 2 vials, measure out 70 ml of the yeast/water. Of course, then you could make a starter as if the yeast was purchased from a store.