July 21, 2010
One Way Valves & Roasted Coffee Storage
??
This article has helped me understand exactly how one way valves do their job.
??
??
??
Why do these work and why does the roasted coffee taste better?
…
The excess (fully mixed gasses) pass out of the container through the one way valve (which equalises the pressure and we end up with 60cc left in the container, or 24cc CO2, 29cc N and 7cc O2:
- 40% CO2
- 48% N
- 12% Oxygen (but now of course at a lower partial pressure, so less of it to react with the coffee)
Now I have made some approximations and also used 60 and 40cc to make the numbers a little easier. But in general it’s reasonably safe to say that the concentration of Oxygen will drop considerably. This seems to be enough to slow down staling considerably, because of course as the Oxygen is used up in oxidation reactions (staling), the % of it will drop still further.
The one way valve bag or jar, do seem to carry significant advantages here, mainly because of the “real” drop in available oxygen for oxidation processes.