Learning Coffee - Pressurized Portafilters

A portafilter is where coffee is placed, when brewing espresso. It’s made to withstand the water pressure of espresso machine, typically 9 bar (130 psi or 900 kPa).

A variation of the portafilter is the pressurized portafilter. This is also known as double-walled portafilter. We’re going to be talking about this variation today, after reading this and this.

How does it work

A pressurized portafilter is composed of two walls, inner and outer. The inner wall is identical to a normal portafilter. The outer wall is solid, except for a single pinhole.

The outer wall has a release valve that requires pressure before it opens. Brewed coffee will flow from the inner wall but meet this restriction. It will build up pressure before it can proceed. This mimics the pressure built in by a normal puck of coffee.

This type of portafilter uses coarser grind, such as pre-ground coffee at the store. Normal espresso grind is too restrictive and prevents adequate pressure to build up and open the release valve.

Why use it

A pressurized portafilter is recommended to beginners as it eases the espresso learning curve.

PPF is beginner friendly, as it removes many variables when you’re first learning. Pulling a good shot of espresso requires dialing in:

• dose
• grind
• puck prep
• temperature
• pressure
• beans
• milk steaming, for lattes

It’s a very steep learning curve, with a high minimum bar to begin to qualify. Using a PPF lets beginner’s focus on the other variables first.

Puck Preparation

Puck preparation has a lot of variables to handle. The restriction on the portafilter has guaranteed pressure, regardless of the contents of the chamber.

• allows for a wide range of grind sizes to be used
• even tamping is not as crucial
• dosing is not as crucial

This makes it forgiving if you are using pre-ground beans or if your grinder is not as high-quality.

Why don’t we always use a PPF

But if it’s easier, why don’t we always use it? Although it’s more forgiving, it doesn’t allow us to use fine grounds. Fine grounds have increased surface area, which is what allows more coffee oils to be extracted. Pressurized portafilter will have less body and extraction than normal espresso.

Once we have gotten a grasp on the variables, the pressurized portafilter is holding us back from the espresso potential.

Crema

The crema produced by a pressurized portafilter is aerated, which causes it to foam up. It’s literally being sprayed out of the small hole and ejects at a high velocity.

This foam is not desirable, it’s akin to macrofoam when steaming milk, instead of microfoam. The latter is better incorporated into the drink.

Many say the crema is worse or taste bad. However, it’s hard to take at face value, as the variable that is not often controlled for is the total crema volume. Since the crema is aerated, we should expect more volume. I suspect that there is less crema extracted, due to coarser grinds, which would make it taste under-extracted.