The Osma is a compact device that looks like a home espresso machine but functions very differently. That’s because the Osma makes cold brew, not hot espresso, and it uses a form of sonic vibration to do the brewing in 90 seconds.
The company claims the technology is a new breakthrough, as reported in some articles such as the one by TechCrunch. However, this is not entirely correct. In fact, we wrote about another device using a similar extraction principle last year, although there is some question about whether that product ever shipped based on the number of complaints.
How it Works
What Osma does differently, is to combine the sonic agitation with pressure and recirculation to excavate the coffee grinds.
The engineering design, it must be said is quite elegant. All the components of a regular espresso machine look to visually be there, but each has a different function.
For example, the regular looking E61 58mm portafilter holds coffee, but you don’t worry about puck preparation or tamping as the coffee sits loosely in the basket. As the coffee contained in the basket gets wet and starts to bloom, the gasses released are trapped, creating 10 bar of pressure which assists the extraction.
Normally, a high water temperature of 90-95℃ is needed to extract the flavour in a process called excavation. The Osma isn’t using hot water but relies on sonic vibration at a particular defined frequency to agitate the grains and expedite the extraction. The company refers to it as the ‘harmonics’, and this is the technology that cold brew nerds have been experimenting with for years. I found the first patent filed by a Korean inventor in 2015.
Osma has also filed a patent, but it is not for the sonic vibration, which will have prior art, but for the ‘Recirculation Infusion’ – where water is pumped from the glass back through the coffee grinds for further extraction.
The company claims a final extracted yield of more than 20%, which puts it in the ballpark of regular cold brew.
What looks to be a steam wand, in fact is part of the brewing design. It is more like a straw that sucks water from a glass and pumps it through the portafilter, where coffee is extracted and sent back into the glass, where again it is recirculated for further extraction, until the process is complete.
Some may consider their design ugly – in my eyes, it resembles a nuclear power plant – but it has the shape of a home espresso machine, making it immediately identifiable to the consumer.
The engineering solution looks like the best application of this sonic technology I’ve seen to date. However, it’s another pre-order, which means you’re risking your money to a company with no track record of delivery. At $695, it is not cheap