Stir Plate Magic

Yeast & Fermentation
1

Back again, this time with a couple of questions about stir plates and yeast starters.

  1. Concerning yeast starters, I noticed that BS2 indicated that using a stir plate increased the yeast population by nearly 2.5 times as opposed to using the same amount of starter without a stir plate. This changed the starter volume from 1.56 liters without a stir plate to .41 liters with a stir plate. I went ahead and made a 1 liter starter just because this is what I’ve always done - should I be able to sleep at night after making a half liter starter on a stir plate for a 1.047 beer?

  2. For my starters, I’ve been using a ratio of 1 gram of DME to 10ml of water, adding nutrient and boiling for 15 minutes. At the end of the boil, I notice that I’ve usually lost around 20% of my volume – I was wondering if this much boil off adversely affects the starter.

Again, thanks to all…

2

  1. I’ve read it can double the cell count. Pitching a vial/smackpack of yeast in a liter is kind of a minimum in my mind, it gives the yeast precious little time to replicate before the sugar is used up. Overpitching is not really much of a concern unless you really want the kind of esters that come from a low pitch. Have a couple fo homebrews and sleep soundly.

  2. At 40ppg for DME, a starter at 1.040 (average to slightly above for a starter) means 10 points per quart. Your use of 1g/10ml = 100g/L is around 1.033, which is perfectly fine for starters. I kind of like a little stronger starter because I tend to use less than the standard 2L starter.

Don’t think you have to run the stir bar fast enough to beat the starter to a froth either, just the movement of the wort is enough to provide plenty of aeration.