How Does Portafilter Temperature Affect Espresso with Blend Coffee?

A controlled test compared espresso pulled through a room-temperature portafilter, a preheated one, and one held at high temperature on the group head. All three groups used the same blend coffee beans, with 19.7 grams of grounds yielding 38 grams of liquid in 27 seconds and water at 94C. The aim was to check aroma, acidity, sweetness and aftertaste for each temperature state and see which practice suits daily bar work.

Baristas disagree on the method. One side argues the group head is already hot, so leaving the portafilter locked on it overheats the basket and lets aroma escape faster once grounds drop in. The other side holds that only constant warmth keeps the portafilter temperature steady between shots. The comparison of room temperature, preheated and long-held high temperature setups sets out what each approach does to the cup.

When extracting espresso, should the portafilter be left at room temperature or kept warm by locking it onto the group head? Different baristas have different opinions on this. Some worry that the high temperature of the group head will overheat the filter basket and accelerate the loss of coffee grounds' aroma; others believe that keeping it warm is the only way to maintain a consistent portafilter temperature. Front Street Coffee specially designed three sets of controlled experiments for this, using a room-temperature portafilter, a preheated portafilter, and a long-term high-temperature portafilter to extract the same "Sunflower Warm Sun Blend Coffee Beans," comparing aroma, acidity, sweetness, and aftertaste one by one, to see exactly what taste changes temperature differences bring, and which method is more worth recommending in daily operation.

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After espresso extraction is complete, should the portafilter be placed directly on the drip tray to return to room temperature, or remain locked on the group head to stay hot? Baristas are divided on this.

Some people think there is no need to keep it warm, reasoning that the group head itself is quite hot, and if the portafilter is left locked on it for a long time, the filter basket temperature will rise too high, and after the coffee grounds fall in, the aroma will dissipate faster.

Others insist that it needs to be kept warm, believing that only in this way can the overall temperature of the portafilter remain consistent.

To verify which practice is more reasonable, Front Street designed three sets of controlled experiments, using a room-temperature portafilter, a high-temperature portafilter, and a preheated portafilter respectively, to observe what differences in taste the coffee extracted under different temperature conditions actually has.

This experiment selected "Sunflower Warm Sun Blend Coffee Beans" as the subject. On the test day, the espresso output parameters were 19.7 grams of coffee grounds extracting 38 grams of coffee liquid, with an extraction time of 27 seconds. All three experimental groups used 94°C water temperature and 10 bar pressure for extraction.

Room-temperature portafilter

A room-temperature portafilter is simply a portafilter placed in a room-temperature environment. On the test day, the indoor temperature was 25°C, and the temperatures of the filter basket, the filter basket frame, and the spout were all measured at 24.7°C.

The espresso after extraction performed as follows: the aroma had a prominent fermented wine scent; on the palate, there was a mixed berry-like sweet and sour taste, a vanilla ice cream-like sweetness and smoothness, and a caramel-like aftertaste. The body was rich, with the acidity slightly prominent.

Preheated portafilter

A preheated portafilter is locked onto the group head before extraction, the switch is quickly turned on to preheat for 5 seconds, then it is removed, wiped dry, and filled with grounds. At this point, the filter basket temperature was 34.1°C, the filter basket frame temperature was 31.2°C, and the spout temperature was 32.3°C.

The espresso after extraction performed as follows: the aroma had an obvious fermented wine scent; on the palate, there was a berry-like sweet and sour taste and a liqueur chocolate flavor, a vanilla cream-like smoothness, and a hazelnut caramel aftertaste. The body was rich and overall balanced.

High-temperature portafilter

A high-temperature portafilter is one left locked on the group head for a long time (more than 15 minutes). At this point, the filter basket temperature reached 52°C, the filter basket frame temperature was 58°C, and the spout temperature was 55.5°C.

The espresso after extraction performed as follows: the aroma had a dark chocolate scent; on the palate, there was a rich dark chocolate and nutty aroma, but immediately afterward a smoky flavor and burnt bitterness appeared. The aroma was insufficient, and overall it was rather uncomfortable to drink.

Front Street's "Sunflower Warm Sun Blend Coffee Beans" features a style of wine aroma with a touch of berry acidity. It drinks rich and special without being too cloying. The vanilla cream-like sweetness and smoothness are also why many customers love this bean.

From the experimental data, the espresso made with the preheated portafilter performed in a more balanced way. The main flavors could all be felt, with distinct layers and overall harmony, and the various tastes did not compete with one another.

In the espresso made with the room-temperature portafilter, the berry acidity was more prominent. If you prefer espresso with obvious acidity, you can try making it with a room-temperature portafilter.

Overall, if not tasted carefully, the difference between espresso made with a room-temperature portafilter and a preheated portafilter is actually not that big. But if used to make Americano or latte, the preheated portafilter will show better aroma.

According to the experimental results, Front Street prefers to leave the portafilter at room temperature. Leaving it locked on the group head for a long time not only fails to make the overall temperature of the portafilter consistent, but the sustained high temperature also accelerates the volatilization of low-molecular-weight and medium-molecular-weight flavor substances in the coffee grounds. At this point, high-molecular-weight flavor substances will become prominent (such as smoky and burnt bitter notes).

In addition, leaving the portafilter locked on the group head for a long time will also accelerate the aging of the silicone gasket. If you find that the portafilter cannot be positioned straight after locking in, or that water leaks during extraction after it is tightened, remember to replace the gasket in time.

The above content is compiled by CoffeeHunters, a coffee news website.