Bottle harvesting yeast, step up question

[beergolf]

I am ready to try harvesting yeast from a bottle. My stir plate should arrive any day now. Have a case of Bell's Amber ready to drink.

I have searched and see a lot of different step up schedules everyone uses. Some just jump right in and others take their time. My theory is that the first feeding should be small and easy for the yeast to eat, to get them going and then slowly build it up over the course of a week.

I think that I should start out small, maybe 125 ml of 1.020 wort and the dregs from 3 bottles.

Then a day later add 250ml of 1.040 wort.

A couple of days later add another 500ml.

Then finally add another 1000ml and it should be ready to decant and pitch.

What do you experienced bottle harvesters think?

 

[MalFet]

There are really two factors at stake when choosing a stepping schedule: risk of infection and material efficiency.

If you toss ten million cells into ten gallons of wort, you are giving the other flora and fauna in your system plenty of time to get a leg up on the yeast. Plus, you're wasting a lot of DME.

125mL of 1.020 is a touch higher than I typically start with for dregs, but should work fine. From there, I step up by factors of 4 or 5. The literature says to use a factor of 10, and I'm sure that's the most efficient, but I've had better results with a smaller interval. A typical course for dregs would be like 50mL -> 250mL -> 1.5L.

 

[Clementine]

Maltose falcon web article on yeast propagation and maintenance was a great help to me when I first was stepping starters from slants. In there it recommends a stepping schedule of less than 10 fold and some brewing schools (I think German) teach 4 or 5 fold steps. I'm guessing a slant probably has as much viable yeast as a bottle and my typical stepping schedule slant (baby food jar) ->50 -> 150-200ml -> 1000ml or Slant 10ml -> 50ml etc etc. I also evaluate each step, ie did it take the normal amount of time, how much yeast sediment can I see grow in the container. If anything is not right the I might slow down the step rate or redo a step. The first step (no matter how you get there, frozen,slant, bottle harvest) always is slow as the yeast are pretty knocked about. I crash cool, decant and swirl and pitch all my steps accept the 50ml and below. I test the spent wort, taste, smell, SG. Any off flavors or smells (should be slightly sour, very oxidized) or a really low SG (1.001ish) and back to the start.

As a separate note, I like to plate and streak out the yeast I harvest from a bottle just to guarantee that I'm not getting any stray bugs. This is really easy to do with agar and a pressure cooker and it ensures cleanliness of the final product (if you have good procedures). Actually a pressure cooker was the second best thing after my stir plate for yeast production, cheapest best way to sterilize everything (including flasks with wort in them and the aluminum foil cover)

Also a stir plate really helps with the amount of yeast you generate, you will be amazed at how your yeast cakes takes off once you get it on the stir plate. Some people (I used to think this) that you have to leave it on the stir plate for two days. Now I just leave it on the stir plate until you see the color change, from wort with some bubbles to milky color as the yeast flocks out. As soon as the yeast flocks the show is over let it sit for a few hrs (do 12ish hrs) then crash cool,decant, warm and step.

More thoughts (I'll shut up after this), I like to pitch at high krausen but I don't like adding liters of oxidized wort to my fermenter. So when I reach my final step, I crash cool and wait to brew day. Morning of or night before if I'm starting early, I do a regular starter with my decanted slurry from my final step not on the stir plate and use wort of similar type to my brew (I have lots of canned wort to choose from). This wakes my yeast up and gets them in the eating mood and they take off in the fermenter within hrs. I feel really comfortable with my really short lag time as it reassures me that it is my team that is doing the fermentation in the wort not the gate crashers of microbes that are everywhere.

Step on o'creator of yeast and enjoy!

Clem

 

[beergolf]

Thanks for the info. Looking forward to my first yeast harvest.

I'll let you know how it goes as soon as my stir plate gets here.