Nedafor en liten artikkel fra det siste nyhetsbrevet til Lalleemand. Jeg mener den gir et argument for å gjenbruke gjær. Det er i og for seg ikke noe vi ikke har hørt mange ganger, men her er i alle fall grunnlaget en studie, og ikke bare anekdotiske data.
Gjengir den her fordi jeg tenker at det er relevant om man tenker å basere seg på å bruke ny tørrgjær hele tida.
Dried brewing yeast has earned an important place in modern breweries,
thanks to its ease of use, cost savings, and long shelf life. For many years,
however, there has been an open question: Can dried yeast perform just
as reliably as liquid yeast when repitched across multiple generations?
To address this, our team at Oregon State University compared liquid-
propagated and dried forms of the same lager strain, LalBrew Diamond™,
focusing on fermentation performance, flavor outcomes, and yeast stability
through four successive fermentations.
Experimental design
The trial involved 150-liter brews made from a wort of 80 percent pale lager
malt and 20 percent light Munich malt, targeting a final alcohol content of
5% ABV. Fermentations were launched with either liquid-propagated yeast
or dried yeast, and the harvested yeast was then repitched through four
generations. Throughout the process, we tracked fermentation kinetics,
yeast physiology, beer chemical composition, and sensory outcomes.
Variation in G0 for both liquid and dry
One of the clearest findings was that the very first fermentation, Generation
0, stood apart from later ones. Both liquid and dried yeast behaved differently
in G0 compared to G1 and beyond, reflecting the yeast’s shift from aerobic
propagation to anaerobic fermentation. The effect was more pronounced
with G0 dried yeast, and it is hypothesized to be due to the compounded
stress of dehydration and rehydration during the transition from aerobic
propagation to anaerobic fermentation. Additionally, inconsistencies in
pitching rate — stemming from difficulties in standardizing viable cell
counts between liquid and dry formats — may have contributed to the
observed variation.
As a result, G0 fermentations with dried yeast showed more noticeable
shifts in performance and in the flavor of the finished beer. This observation
aligns with long-standing knowledge in the brewing industry: Brewers
recognized the first generation of a yeast crop often tastes different from
subsequent ones and many routinely blend G0 beer with later batches to
smooth out flavor variation.
Variation vanishes after first repitch
The more important story, however, was what happened next. From the
first repitch onward, dried yeast performed just as consistently as liquid
yeast. Fermentation stabilized, flavor outcomes were steady, and no
meaningful differences were detected between the two forms from G1
through G3. In terms of microbiological stability, dried yeast also proved
equivalent to liquid yeast. Risks of contamination or genetic drift were
no greater with dried yeast, provided that brewers began with clean
yeast and maintained tight microbiological control during repitching.
Taken together, these results demonstrate that dried yeast can be
repitched with the same reliability as liquid yeast, offering breweries
not only the logistical and cost advantages of dry formats but also
the confidence to carry yeast forward across multiple generations.
For brewers, the key message is clear: dried yeast is not just for
single-use pitching. It is a robust, repitchable option for producing
consistent beer at scale.By Jun Yomo¹, Jeffrey Clawson²,
and Thomas H. Shellhammer²,
¹Suntory Spirits Ltd., Tokyo, Japan
²Oregon State University, Corvallis, Oregon, USA
Dry yeast repitching:
flavor and performance
over multiple generations
For more information, please visit us online at
www.lallemandbrewing.com
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