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Name: Wayne D.
Status: Eduactor
Age: 50s
Location: N/A
Country: N/A
Date: N/A 


Question:
Carbon dioxide is made by yeast and other microorganisms. Beer fermentation is a good example. We know that ethanol inhibits fermentation at about 8% for a beer yeast at about 13% for a wine yeast which can tolerate greater concentrations.

My question is: what is the maximum pressure of carbon dioxide that a yeast fermentation can achieve ? My guess is that dissolved carbonic acid will be the agent that inhibits the enzymes and the pressure per say is not the issue. Any thoughts ?



Replies:
I suspect you are correct. The pH of water saturated with CO2 is about 3.8.

Tap water is between 6.5 and 8.0 depending upon what salts etc. are present. The pH of wines varies between 2.8 and 3.8 depending upon what other acids are present, e.g. tartaric acid is a common acid found in wines.

Vince Calder


I cannot answer your question directly since I never tested to what pressure yeast is resistant, or how much pressure carbon dioxide of biological origin can produce.

However, yeast has a strong cell wall and is a hard nut to crack. Also it can produce spores which are even sturdier. My guess is that the pressure is indeed not the issue.

Trudy Wassenaar



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