Coffee Data Science
Coffee Dosing Tubes are Unnecessarily Over-Priced
Rethinking some coffee tools
Many coffee people have been using single dose tubes to store their coffee. The more expensive ones offer a single one-way valve for each tube as typically would be on a bag of coffee. However, I think coffee tubes like this are over-priced because of physics.
This is a typical Normcore coffee tube where each tube has a one-way valve to let gas out but not let gas in.
Coffee beans degas over time, and they can produce a decent amount of gas. Roughly, 10 mg per 1 gram of coffee. This chart comes from Samo Smrke’s data on degassing based on dark, medium, and light roasts.
Let’s play with some numbers. Assume after 1 week, 0.005 mg / g of gas has come out of the beans. Let’s assume a dose of 24 g, so 0.12 g of CO2 will be released after 1 week.
Now, let’s assume we put this dose into a 100 ml tube. Assume the coffee beans have a density of 0.40 g/mL (very light roast), so they take up 60 mL of volume in the tube.
As a result, there is 40 mL of air left in the container, and based on the weight of air, that is 0.048g of air.
Air has a lower density than CO2, so in a dose tube, the air will be forced up by the CO2 as the coffee beans degas. For the one-way valve case, all the oxygen will be forced out of the tube.
So what if you don’t have a one-way valve? The air will be pushed to the top of the container. What if we had a cheaper container, like this Medea one for breast milk?
If the beans take up 70 ml of a 100 ml container, then no air should be touching the beans, just CO2 as the air will be squished at the top.
Cost
Looking at the cost per container, the Medea containers are really cheap, but they aren’t glass like Weber and some others. They also do not have one-way valves.
While dosing containers are cute, they are overly expensive for functionality. If these dosing containers indeed provide good valve, cheaper options would work.
Appendix A
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Further readings of mine:
My Second Book: Advanced Espresso
My First Book: Engineering Better Espresso
