Changes

The presence of more than 2-5 ppm of dissolved oxygen (DO) in the wort might also reduce the risk of botulism <ref name="Pérez-Fuentetaja">[https://link.springer.com/article/10.1007/s10750-005-0011-1 Influence of Limnological Conditions on Clostridium Botulinum Type E Presence in Eastern Lake Erie Sediments (Great Lakes, USA). Alicia Pérez-Fuentetaja, Mark D. Clapsadl, Donald Einhouse, Paul R. Bowser, Rodman G. Getchell, W. Theodore Lee. 2006.]</ref>(more references needed), however the levels of DO in wort that has been cooled in a coolship has not been well studied, and neither has the amount of DO during the first few days of fermentation. Dissolved oxygen in wort that is near boiling temperatures will be limited due to Hentry's law, but some amount of atmospheric oxygen will be absorbed as the wort cools over night <ref>[https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/respiratory-system-22/gas-laws-210/henry-s-law-1032-977/ "Henry's Law". Bouldess.com website. Retrieved 03/07/2017.]</ref><ref>[http://docs.engineeringtoolbox.com/documents/639/oxygen-solubility-water-2.png Graph of oxygen solubility in water at different temperatures. Engineering Toolbox website. Retrieved 03/07/2017.]</ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1599584193403122/?comment_id=1599693336725541&reply_comment_id=1600361503325391&comment_tracking=%7B%22tn%22%3A%22R%22%7D Bryan of Sui Generis blog. MTF discussion on dissolved oxygen in wort cooled in a coolship, and the accuracy of DO meters. 03/02/2017.]</ref>. Some reports of DO in wort cooled in a coolship MTF include ~4 ppm in a small coolship that was 2' x 1' x 1', and 3.6 - 3.8 ppm in wort cooled overnight in an open 10 gallon boil kettle <ref>[https://www.facebook.com/browse/likes?id=1605741916120683 Amaral, Justin. MTF discussion on dissolved oxygen in coolship wort. 03/07/2017.]</ref>. The DO levels from a commercial sized coolship (10 BBL; 6' x 10') were reportedly 2.6 ppm after the transfer to the coolship while the wort was still hot, and 5.1 ppm after the wort cooled for 14 hours <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1601687793192762/?comment_tracking=%7B%22tn%22%3A%22R%22%7D Coker, Ryan. MTF discussion on dissolved oxygen in wort cooled in a commercial coolship. 03/07/2017.]</ref>. The dissolved oxygen in the wort, however, could be quickly consumed by aerobic bacteria and yeast. Additionally, some strains of ''C. botulinum'' are more oxygen tolerant than others. Therefore, DO levels should not be relied upon for preventing botulism. Instead, a timely (within 4 days has been a suggestion, however no one really knows how long it takes ''C. botulism'' to grow in anaerobic wort and produce enough botulism toxin <ref>[http://beerandwinejournal.com/botulism/ "Storing Wort Runs the Risk of Botulism". Dr. Colby, Chris. Beer and Wine Journal blog. 04/17/2014. Retrieved 03/07/2017.]</ref>) reduction in pH below 4.6, and an increase in alcohol (decrease in gravity), are more effective measures for making sure that botulism is not a concern <ref name="Pérez-Fuentetaja" /><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1604630206231854/?comment_tracking=%7B%22tn%22%3A%22R%22%7D Bryan of Sui Generis Blog. MTF discussion on dissolved oxygen in wort cooled in a coolship. 03/07/2017.]</ref>.

* [https://www.facebook.com/groups/MilkTheFunk/permalink/1986941961334008/ MTF thread on chilling overnight during warmer than normal temperatures.]