Re-pitching advice

Should I make a starter and how big should it be for harvested yeast, that is about two weeks old, been washed, and going into a 1.090, 5.5 gal. wort?

I've recently started harvesting and re-pitching my yeast, I typically use Mr. Malty's pitch calculator to determine how big of a starter I'll need but I noticed that is not an option for pitching from a slurry. I know the slurry will have a higher cell count than say a vial of white labs, but it's been in the fridge for two weeks and I think I should give it a boost.

Any thoughts are much appreciated...

DixieBull said:

Should I make a starter and how big should it be for harvested yeast, that is about two weeks old, been washed, and going into a 1.090, 5.5 gal. wort?

I've recently started harvesting and re-pitching my yeast, I typically use Mr. Malty's pitch calculator to determine how big of a starter I'll need but I noticed that is not an option for pitching from a slurry. I know the slurry will have a higher cell count than say a vial of white labs, but it's been in the fridge for two weeks and I think I should give it a boost.

Any thoughts are much appreciated...

Click to expand...

I think you should look at Mr Malty again. There is a repitching from slurry tab.

Yes, I see that, my question is about starters with slurry's though.

DixieBull said:

Yes, I see that, my question is about starters with slurry's though.

Click to expand...

How much slurry does it tell you you need and how much do you have? You can use yeastcalc.com to calculate starter size once you backcalculate how many billion viable cells you have.

It says to pitch about 155ml of slurry. I have over 300 ml harvested but it has been sitting in the fridge for two weeks and everything I've read says if it's over 1 week - 10 days that a starter with nutrient in it will help to revitalize the yeast.

I'd just not make a starter, but use the right amount of slurry, accounting for the loss in viability. If you make a starter, you lose the benefit of the yeast being accustomed to your beer. This is assuming you aren't repitching after a big beer. One less chance of contamination as well. If you do make a starter and intend to reuse the yeast from the batch, be sure to pitch the right amount into the starter so that you have the right amount of yeast at the end. That is to say, use less than your 155mL in a starter. I'm make the starter about 1/10th - 1/20th the batch size, depending on the propagation method.

If it's only been a few weeks, I'd just use slurry. Hopefully you can be sure that the yeast had not accidentally frozen in the fridge.