From the HBD Archive
From: MARK <GRYSKA@cs.umass.EDU>
Subject: Liquid (pure) Yeast Cultures
Date: 1988-11-22 01:28:00 GMT

The question of whether to use dried yeast or liquid (pure) yeast
cultures boils down to: Do you want to make good beer or great beer?
Dried yeast cultures are inevitably contaminated and contain a high
proportion of dead yeast cells, a properly handled liquid culture
will have neither. Also, liquid yeast cultures are pure strains of
brewing yeast, which is not necessarily the case with dried yeast.
(especially lager yeast) Having pure cultures available allows a
brewer/brewster to select the exact characteristics that the finished
beer will have, this includes aroma, flavor and body.

My experience using liquid cultures has been good to excellent. It
requires a little more planning and a little more care but it is most
definitely worth it. I've used both M. eV. and Wyeast products with
success but I lean a little more toward Wyeast because I think it is
easier to use and I have a local supplier. The nice thing about
Wyeast is that it comes in a sealed envelope which contains a sterile
wort. You can start a yeast going in this wort without fear of
contamination and pitch a greater number of healthy cells into a
starter bottle or directly into your wort.

The most important thing to consider when pitching any yeast is the
resulting lag phase. The longer the lag phase the greater the chance
that little nasties will get a head start and ruin the beer. I think
this should be the determining factor for how much yeast to pitch. A
3 hour lag phase is great and 12 hours should be at the outside limit.
Some cultures will require more of a head start than others.

Some tips:

- Always pitch the yeast/starter when it is at the height of krausen.

- My Wyeast supplier recommends pitching the yeast or starter into
the wort at 70 degrees F. and let the wort cool slowly to the
desired fermentation temperature.

- Aerate your starter and your wort, I swirl the starter bottle after
the yeast has been pitched and pour the COOLED wort from on high
into the fermenter.

- Pick your culture carefully according to the desired characteristics
for the finished beer, your fermentation temperature(s) and the
composition of your wort. (I like Wyeast #338 "German Alt")

According to Greg Noonan's "Brewing Lager Beer":

- A good (strong fermenter) culture should be pitched at 8.5 g/gal.

- 4 fl ounces of wort (starter) should produce 2-4 g pure yeast.

This means using a starter of up to 88 fl ounces for a 5 gallon
batch! In practice I have had good results using one pint.

Some good resources: Noonan "Brewing Lager Beer", Papazian TCoJHB,
Dave Miller's new book, several Zymurgy articles including Miller's
article in the Fall '88 issue, and on and on and on. In short, if you
haven't tried using pure cultures then you haven't tried brewing the
best beer that you have ever brewed.

- mg

Mark Gryska

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