Changes

Yeast washing is the practice of exposing a yeas yeast slurry to extreme acidic conditions in order to destroy bacteria contaminants in the slurry, and it has been used for over a century in the brewing industry to help reduce the potential for lactic acid bacteria spoilage. Although techniques might vary throughout the brewing industry, the most typical technique is to add phosphoric acid to a slurry of yeast until a pH of 2 is reached, and then the slurry is stored for 2 hours at 5°C (41°F). While phosphoric acid is a good choice for acid washing because of being inexpensive compared to other acids, its tendency to not kill yeast, and its lack of affecting beer flavor, it also does not kill some contaminants such as ''Shimwellia pseudoproteus''. It has also been proposed that chlorine dioxide, a disinfectant that is often used in the vegetable, meat, and water treatment industries, can be successfully used to wash a yeast slurry, with the first study on this reporting that a concentration of 78 mg/L (concentration value is for the entire slurry) and stored for 30 minutes at 8°C (46.4°F) <ref>[https://link.springer.com/article/10.1007/s00253-020-10534-x Modeling the inactivation of Lactobacillus brevis DSM 6235 and retaining the viability of brewing pitching yeast submitted to acid and chlorine washing. Munford, A.R.G., Chaves, R.D., Granato, D. et al. Appl Microbiol Biotechnol (2020). https://doi.org/10.1007/s00253-020-10534-x.]</ref>.