What's the Difference Between Siphon Coffee and Pour-Over? Can Siphon Brewers Use Filter Paper Besides Flannel? How Does the Siphon Principle Work?

Siphon Coffee: The Elegant Brewing Method of a Bygone Era

Siphon brewers, with their unique coffee preparation method and remarkably high visual appeal, once became the popular coffee brewing apparatus of the last century. FrontStreet Coffee mentioned last winter that with the rise of retro trends today, more and more coffee shops are adding siphon coffee options to their menus, allowing friends of the new generation to have the opportunity to enjoy the flavors of the past.

Because it is also a brewing method for single-origin coffee, people inevitably compare it with the modern mainstream extraction method—pour-over coffee. Friends who have tasted siphon coffee know that the differences between siphon coffee and pour-over coffee are quite significant, both in terms of mouthfeel and flavor.

Pour-over coffee tastes cleaner, with more distinct layers and prominent flavors. Meanwhile, siphon coffee offers a richer mouthfeel, more intense aroma, and a more robust flavor. Therefore, many friends are curious about why there's such a significant difference between the two. Today, FrontStreet Coffee will share why siphon and pour-over brewing methods produce such different results!

Differences in Extraction Methods

The extraction method for pour-over coffee is primarily "drip filtration," also known as "filtration." As hot water is poured to extract the coffee, the coffee liquid simultaneously seeps through the filter paper. This method is called drip filtration. Observant friends might notice that FrontStreet Coffee says "primarily" rather than "exclusively." Because during the pour-over brewing process, there's also an element of immersion extraction, meaning water doesn't just flow through the coffee grounds but stays for a brief time before seeping through the filter paper. Therefore, pour-over coffee isn't entirely a drip filtration extraction method.

Many friends might think that siphon coffee's extraction method is "siphon-style," but that's not quite right. The siphon brewer merely uses the siphon principle to draw hot water to the upper chamber, which isn't for coffee extraction itself.

When hot water is drawn to the upper chamber, adding coffee grounds for immersion marks the official beginning of extraction. So, strictly speaking, siphon coffee's extraction method should be "immersion." By immersing water and coffee grounds, flavor compounds are extracted from the powder.

Because immersion extraction uses all the hot water in contact with the coffee grounds, when substances in the water reach a certain concentration, the dissolution rate slows down, and it no longer extracts as many flavor compounds from the coffee—this is what we commonly call reaching saturation. Therefore, siphon coffee tastes relatively balanced, with abundant aroma, but the flavors won't be too prominent (this is also somewhat related to the second factor). In contrast, drip filtration extraction continuously uses pure hot water to extract flavor compounds from the coffee. Pure hot water has plenty of "storage space" and will continuously extract flavor compounds from the coffee. Therefore, pour-over coffee produces coffee with fuller flavors, but it's also more prone to over-extraction.

It's worth mentioning that compared to conventional immersion extraction, siphon's immersion extraction is somewhat different. Due to the siphon principle, hot water is continuously heated during the coffee extraction process to ensure the lower chamber has enough air to keep the hot water in the upper chamber. Therefore, siphon's immersion extraction maintains a completely constant temperature, while conventional immersion and drip filtration extraction are both processes of continuous heat loss, where water temperature gradually decreases over time. This results in siphon having a higher extraction rate, and with stirring, it can complete extraction in a shorter time.

Differences in Filtration Methods

Besides extraction methods, the filtration methods of these two coffees also greatly affect the final result. Pour-over coffee uses high-density filter paper, which allows only coffee liquid to pass through—nothing else can permeate through.

Meanwhile, siphon brewers primarily use flannel filter cloth, although filter paper can also be used. However, because it cannot provide complete coverage, it cannot form a "sealed" space like pour-over coffee. Fine particles, oils, and other substances can pass through gaps into the lower chamber, joining the coffee liquid, which is why siphon coffee appears more turbid. Although oils and fine particles make the coffee liquid less clean, they provide a richer mouthfeel to the coffee. This is why siphon coffee tastes more mellow.

In contrast, pour-over coffee's excessive filtration results in the loss of some richness, but this is also one of its great advantages—ultimate cleanliness! Now we understand why there's such a big difference in taste between siphon and pour-over coffee. It's not just the impact of extraction methods, but more importantly, the different filtration systems that give the coffee liquid completely distinct mouthfeels.

- END -