HOMEBREW Digest #13 Mon 21 November 1988

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		Rob Gardner, Digest Coordinator

  Liquid (pure) Yeast Cultures (MARK)

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---------------------------------------------------------------------- Date: Mon, 21 Nov 88 21:28 EDT From: MARK <GRYSKA at cs.umass.EDU> Subject: Liquid (pure) Yeast Cultures 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 gryska at cs.umass.edu Return to table of contents
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