![]() ![]() The fermentations were run in duplicate to ensure consistency. This rate is a bit low for Isar Lager but we wanted to keep pitching rate consistent between the strains. We then took the stored yeast slurry and pitched it into miniature wort test fermentations at a rate of 10 million cells/mL. We chose 3 and 4 weeks as this is around the maximum amount of time most brewers and yeast suppliers will recommend storing yeast between batches of beer. The yeast was tested at over 95% viability when it was cropped at the brewery, indicating this yeast was of excellent health coming out of the beer fermentation.įor this experiment, we stored the yeast in the fridge and pulled samples at 0 weeks (fresh), 3 weeks, and 4 weeks in order to assess the impact that yeast storage time has on fermentation performance. Luckily, our friends at Royal City Brewery down the road helped us out with some “gen 1” yeast slurries, freshly cropped and stored at refrigerator temperatures (2-4✬). ![]() Since the yeast produced at Escarpment Labs is packed with pH buffers, micronutrients, minerals, and other factors that radically enhance shelf life, we needed yeast cropped from a beer fermentation in order to obtain accurate real-world results. ![]() We decided to put yeast storage, without any additives, to the test! We selected two strains that are not known to be super hardy, but which also aren’t super picky about storage: Kölsch, and Isar Lager.įresh slurry from Escarpment Labs has a long shelf life due to how we grow and feed the yeast. These results are promising and stay tuned for some results from Escarpment Labs testing the impact of pH buffers and nutrients on yeast storage between batches. This study showed that a pH buffer (potassium phosphate) and sunflower oil can help improve yeast viability during storage between batches. If the viability is below 80%, we suggest using the yeast within 1 week of cropping.Ī great study titled "Long Term Yeast Storage: Novel Approaches" was shared at the MBAA conference in 2019 by Matt Couch at Lazarus Brewing. Note 2: Storage time is HIGHLY dependent on the viability of the yeast coming out of your fermentation. Note 1: If you are able to perform a propagation/“vitality starter” step prior to pitching, you can often extend the viable shelf life of your stored yeast up to several months. Increase pitch rate or make a starter if over 2 weeks.Ĭheck for presence of yeast cross contamination using a microscope before reusing. In general, we recommend maximum storage times of yeasts based on the following table: There is not much good information or data out there on how long brewery yeast will last between batches, especially at craft beer scale and with craft beer strains such as ale yeasts. How long can I store my yeast in a brink between batches of beer? If you have any concerns about the health of a repitch however, we always suggest going back to a fresh yeast pouch. Note for homebrewers: you have a lot more flexibility here, if your stored yeast is more than 1 month old we recommend building up a stir plate starter and your yeast should be OK to use for several generations. Our simple answer is: for most yeast strains, plan to reuse it within 3 weeks, although some strains can last longer between repitches. ![]() Since it is more cost effective to repitch liquid yeast, we thought it would be helpful to put together some resources and share some research we did on yeast storage time between batches of beer! One of the biggest challenges and mysteries that brewers using liquid yeast face is how long yeast can be stored in between batches without risk of poor fermentations or off-flavours. ![]()
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