Can bugs survive in fermentation off-gas?

[shoo]

Question. I have a bit of an experiment with CO2 harvesting going on over here. Given that this appears to be working roughly as planned, I am now thinking about re-use, which brings me to sanitization and storage.

The question is ultimately: do I even need to sanitize? The thought is that the balloon is filled with nearly pure CO2 from fermentation. If yeast can't survive in that environment, then I have no problem.

However, there is also likely to be some moisture in there as well from fermentation. One other thought is that the "moisture" is likely to be mostly ethanol, since it has a much lower boiling point, and that should also kill pretty much everything.

Essentially, am I already sanitizing just by chance? Seems too good to be true, but eliminating having to sanitize the balloon for reuse would be amazing.

Thoughts?

 

[ajdelange]

However, there is also likely to be some moisture in there as well from fermentation. One other thought is that the "moisture" is likely to be mostly ethanol, since it has a much lower boiling point, and that should also kill pretty much everything.

There isn't going to be much ethanol in the gas. At 19°C the saturated vapor pressure of ethanol is 40 mmHg but as the mole fraction of ethanol in most beers is around 1% its vapor pressure at this temperature is going to be about 0.4 mm. The vapor pressure of water, by contrast, will be about 17 mmHg. At 35 °C the saturated VP is 100 so at 1% mole fraction the balloon EtOH vapor pressure is going to be about 1 mm with the vapor pressure of water at that temperature being around 42 mm (the water values are saturated but as the H20 mol fraction is about 99% I used them without correction).

 

[ESBrewer]

If there is a chance that there are microbes inside the balloon when you start collecting co2, there is a chance that they will survive, for sure. A little bit of something may enter together with the co2 as well. You would like to carefully sanitize the balloon and connections from the inside before you start and then keep it tightly sealed so I think the co2 would be fine for brewing purposes (for a while, not forever cause in practice you are unable to ensure that no any bugs would enter the balloon).