January 12, 2023

What is syphon brewing & how does it affect coffee extraction?


There are an ever-growing number of ways to prepare filter coffee, each of which has its own effect on flavour and texture. However, for the most part, there are two main ways to brew coffee: percolation and immersion.

With immersion brewing, the coffee is in full contact with the water for the entire duration of the extraction. This enhances the body and aftertaste of a coffee.

One of the most popular immersion brewing methods – particularly in Japan – is the syphon (also known as a siphon or vacuum brewer). This unique brewer includes two separate chambers which rely on vapour pressure and gravity to extract coffee. 

So, how do syphons work, and in turn, how do they affect coffee flavour and texture? To find out, I spoke with two baristas. Read on to learn more of their insight.

You may also like our article on which filter coffee brewing method is best for you.

Takumi Yamashita stirs a syphon brewer in a Japanese coffee shop.

A brief history of the syphon & other vacuum brewing methods

While it’s believed that the first-ever vacuum coffee brewer was invented by Loeff of Berlin sometime in the 1830s, syphons started to become commercially available in the mid-1800s thanks to French inventor Marie Fanny Amelne Massot. 

Around the same time, Scottish engineer Robert Napier designed his Napier Coffee Pot, which also creates a vacuum to brew coffee. Although the brewer received an award from The Institution of Mechanical Engineers in 1856, it was never patented.

Since then, many types of vacuum brewers have entered the market, but the most popular model is the syphon – specifically the Hario syphon, which is widely used in Japanese and Taiwanese coffee shops.

Hirona Yamamoto is a barista at LiLo Coffee Roasters in Osaka, Japan. She is also preparing to compete at the World Siphonist Championship – an event which sees competitors brew three syphons and three signature beverages in a 15-minute performance.

“In the past, and even today, the syphon has been an indispensable piece of equipment for coffee shops in Japan,” she explains.

She adds that while the first kissatens opened in Japan in the mid-18th century, they became more popular after the Second World War, when the country went through a period of economic growth.

“As part of this, more coffee shops began to open, which people used as everyday social spaces,” Hirona tells me. “Because of their aesthetic design, syphons became a fashionable item to have in coffee shops.”

Narumi Sato is the CEO of Belleville Japan, which also operates a location in Paris. She is also the 2016 World Siphonist Champion.

“During this time, the syphon was very popular,” she says. “One of the reasons why it became so common in coffee shops is because baristas are able to do other tasks while brewing coffee with it.”

Narumi adds that while most kissatens primarily focus on pour overs, she believes that interest in syphon brewing will continue to grow, especially in the specialty coffee sector.

Narumi Sato pours coffee from a syphon into a cup at Belleville Japan.

How does it work?

Unlike most brewing methods, a syphon uses pressurised water vapour to extract coffee. Most other coffee brewing methods use either time (immersion) or gravity (percolation) to extract the flavours and aromas from coffee.

By definition, syphons and other vacuum brewing methods brew coffee in an environment where air is removed. Syphons have two brewing chambers: a top chamber, which is where the vacuum is created, and a lower chamber, which is where the brewing water is initially added.

The heat source, as well as the design of a syphon, helps to create a vacuum within the top brewing chamber. This is caused by a difference in air pressure. As the water in the lower chamber boils, some of it turns into water vapour, which in turn means its pressure rises.

As the density of water vapour is much lower than liquid water, the mixture of air and water vapour in the lower chamber expands. This continues until the spout from the top chamber is connected with the lower chamber, which causes the water to draw into the top chamber. 

When the heat source is switched off, the pressure then falls, forcing the brewed coffee back into the lower chamber – but leaving the used grounds behind.

When using any vacuum brewing method, extraction time is usually a lot shorter. This is because of the absence of oxygen and other gases. In this environment, the volatile compounds in coffee can be extracted much more quickly, as there are fewer gas particles to inhibit extraction.

This is especially noticeable with automated vacuum cold brew methods, which can extract cold brew within minutes, rather than hours.

How to brew a syphon

Although many coffee professionals claim that brewing with a syphon can be complicated and time consuming, Narumi tells me that the method is relatively straightforward.

  • Add water to the lower chamber. Narumi suggests using a 1:15 ratio of 16g of coffee (ground slightly finer than for a V60) and 240g of water.
  • Turn on your heat source (ideally to high heat) and place it underneath the lower chamber. No matter which brand of syphon you use, most come with a portable heat source, which is usually either a gas burner or an infrared lamp. 
  • As the water heats up, attach your filter (either paper or cloth) to the top chamber, and place the spout into the lower chamber. Once the water starts boiling, a buildup of vapour pressure will cause it to move into the top chamber.
  • When the majority of water reaches the top chamber, you need to stir it vigorously (traditionally using a bamboo paddle or chopsticks) to create a “whirlpool”. 
  • Add the ground coffee into the water and stir, before placing the lid onto the top chamber to preserve most of the coffee’s aromas. 

Narumi explains that after 25 seconds, the heat source should be turned off, which will pull the brewed coffee back down into the lower chamber. She adds that the total brew time should be between one and one-and-a-half minutes – making it a much simpler brewing method than others.

“When you brew a pour over, you have to completely focus on it for around three minutes,” she explains. “But with a syphon, you only have to concentrate for between 20 and 30 seconds, which makes it significantly easier.”

Hirona Yamamoto stirs water in a syphon brewer.

Why is stirring your coffee so important when using a syphon?

As with any other brewing method, the right level of agitation is important if you want to make sure you get even extraction. However, according to the World Siphonist Championship, to achieve the best possible result with a syphon, you should use the double-stir technique.

This is when you first stir the water to create a “whirlpool” in the top brewing chamber, and then stir for a second time once you add the coffee to the water. 

“The first stir is the most important one,” Narumi says. This is because it ensures more even saturation of the coffee grounds once they are added to the water.

Hirona agrees, saying: “If you don’t allow the grounds to fully saturate, it is more difficult to achieve a high-quality extraction.”

While the first stir can be more vigorous, the second one should be more of a gentle fold to allow the coffee to degas – similar to a bloom when brewing a pour over. 

Ultimately, a sign of executing a high-skilled stirring technique is the formation of a dome of coffee grounds at the base of the top chamber – with larger coffee particles accumulated at the bottom.

Brewed coffee in a syphon.

How does syphon coffee taste?

When brewing a syphon, the coffee is in full contact with the water for the entire duration of extraction – as it is an immersion brewing method. 

However, compared to coffee brewed with other immersion methods, the syphon creates a different sensory profile, particularly in terms of texture and mouthfeel.

This is mainly a result of the vacuum created during the brewing process, as well as using a cloth filter – both of which can produce a more enhanced mouthfeel.

Narumi tells me that this may also be a reason as to why the syphon is so popular in Japan. 

“When I went to the Belleville coffee shop in Paris, baristas were describing the flavour of the coffee, but not the mouthfeel,” she says. “In Japan, people like to describe mouthfeel and different food and beverages.”

This is most likely the result of linguistic differences. Compared to the English language, for example, the Japanese language contains more words to describe mouthfeel.

Narumi adds that there are around 400 words in the Japanese language to describe mouthfeel. This is most prominent in Japanese cuisine, which tends to have much more of a focus on the texture and consistency of food. In comparison, the English language has about 80.

For example, the word torotoro (which roughly translates to “syrupy” in English) describes the texture of liquid which is slightly thicker than water.

Hirona Yamamoto smells coffee brewing in a syphon.

Tips for using a syphon to brew coffee

Hirona tells me that the syphon is a very versatile brewer, and can be used by anyone – no matter their level of brewing experience.

“You can brew any kind of coffee with a syphon,” she says. “It does not matter whether the coffee is light or dark roast, or whether it’s commodity or specialty-grade.”

Narumi agrees, saying that dark roasts can often suit this brewing method well. 

“This is because of the higher amount of oils in darker roasted beans,” she explains. “The increased bitterness of these coffees will become more well-rounded, so it can result in a richer-tasting coffee.”

Many coffee professionals and home brewers use a cloth filter when making a syphon, which allows more of the coffee’s oils to be extracted – further enhancing its mouthfeel.

However, if you do use a cloth filter, you need to make sure it is clean. As cloth filters can be reused many times, if not cleaned and dried properly after every use, they can quickly attract mould and impart sour flavours in your coffee.

To avoid this, after squeezing as much water out as possible, you can store used cloth filters in the freezer and run them under hot water before use.

Takumi Yamashita adds ground coffee to two syphon brewers.

The syphon’s distinctive design and unique vacuum brewing system make it a great addition for specialty coffee shops and home brewing setups. 

With its rich history and unique style, it’s clear that syphons have a place in specialty coffee and will continue to for the foreseeable future.

Enjoyed this? Then read our article on how agitation affects filter coffee brewing.

Photo credits: Hirona Yamamoto, Kaori Umezawa, Takumi Yamashita

Perfect Daily Grind

All quotes from Hirona Yamamoto are translated from Japanese into English 

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