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rtb178 · 11-25-2012, 03:27 PM

Hi everyone,

Yesterday I harvested the dregs from four bottles of Ommegang Scythe and Sickle. I also used my stirplate for the first time. I only have a 3L flask, so I started a little heavy on the starter wort -- 500ml 1.02 wort. We'll see what happens in a couple of days after crashing and decanting.

I know that people suggest starting their harvest with 250ml (or even less). For those of us with just one large flask, I'm wondering if it's possible to start the process with twice as much wort at half strength--e.g., instead of 500ml 1.02 wort, 1L 1.01 wort. Would this do something completely different? Nothing at all?

WoodlandBrew · 11-26-2012, 06:12 PM

If there is adequate nurturance and oxygen cell division in yeast is limited by the sugar content of the wort. Hence, the number of cells produced (for the most part) directly proportional to the sugar in the wort. Is that where your idea came from?

There are some other factors that will make an impact such as cell density. As cell density goes up, division goes down. However, the lower the gravity of wort, the lower the chance that yeast will come in contact with sugar.

It would be interesting to see data on this.

rtb178 · 11-27-2012, 03:21 PM

Quote:

Originally Posted by WoodlandBrew

If there is adequate nurturance and oxygen cell division in yeast is limited by the sugar content of the wort. Hence, the number of cells produced (for the most part) directly proportional to the sugar in the wort. Is that where your idea came from?

There are some other factors that will make an impact such as cell density. As cell density goes up, division goes down. However, the lower the gravity of wort, the lower the chance that yeast will come in contact with sugar.

It would be interesting to see data on this.

I was really wondering because I have a large flask and I didn't want to aerate the wort too much while it was going on the stirplate. i.e., 500ml in a 3l flask is a pretty shallow pool of liquid. My non-scientific mind was thus thinking that I could double the liquid and halve the sugars, and then see what happened.

WoodlandBrew · 11-27-2012, 03:49 PM

Oxygen will encourage cell division, which you want at this point. If you are concerned about the flavor it may impart on your beer then crash and decant before pitching.

kh54s10 · 11-27-2012, 04:01 PM

I don't know if you made a mistake in your gravity points but there is not a huge difference between 1.020 and1.010.

For starting from bottle dregs you will need to do a few steps to get the amount of yeast you need.

You could do the 500 ml at 1.020. Then cold crash and decant
I would then make a couple more steps then a final starter.
500 ml at about 1.020 for about 18 hours - decant
1.5L at about 1.040 for about 18 hours. - decant

This would be my guess to get to the amount of yeast in a vial/pack and then you can procede to make a starter for the gravity of the beer you are making.

Check out yeastcalc.com for information on step starters.

WoodlandBrew · 11-27-2012, 04:30 PM

Quote:

Originally Posted by kh54s10

I don't know if you made a mistake in your gravity points but there is not a huge difference between 1.020 and1.010.

The rest of your post sounds fairly reasonable, but I don't follow you here. The difference from 1.020 to 1.010 is half as much sugar. In a starter the limiting growth factor is the amount of sugar, so the number of cells in a 1.010 wort will be about half of the number of cells in a 1.020 wort with size being equal and adequate oxegen.