[FrontStreet Coffee Barista Notes] Espresso Extraction Techniques: Single Shot, Pre-infusion, and Multi-stage Extraction

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Today, while discussing hand-pour blooming, single-pour extraction, and segmented extraction with colleagues, I wondered what would happen if these techniques were applied to espresso extraction. Better to act than wonder, so I immediately began experimenting.

The star of this experiment is FrontStreet Coffee's Premium Blend, combining Brazil and Colombia in a 7:3 ratio. The grinder is the Feima 900N set to a grind size of 1.7.

Today's Espresso Extraction Experiments

Parameters: Double portafilter / 21g coffee grounds / 40g espresso liquid

Single-Pour Extraction

Technique: Direct extraction of 40g espresso liquid, total time 25 seconds.

Espresso flavor: Caramel, hazelnut, berry, smoky notes. Overall flavor is rich and full-bodied, with caramel sweetness in the aftertaste.

Pre-infusion

Technique: Start extraction for 5 seconds, then pause for 5 seconds (total 10 seconds elapsed), then resume extraction. Total extraction time is 31 seconds.

Espresso flavor: Caramel, cocoa, lemon acidity. The smoky notes are heavier than single-pour extraction, while acidity is also prominent. The sweetness in the aftertaste is less noticeable.

Segmented Extraction

Technique: Extract for 15 seconds, then pause for 5 seconds (total 20 seconds elapsed), then resume. Total extraction time is 32 seconds.

Espresso flavor: Berry, caramel, nutty, smoky notes. The aftertaste has maple syrup sweetness, with an overall softer profile.

In espresso extraction, the single-pour method delivers the most full-bodied flavor with rich layers. The pre-infusion method originally extracts fewer early-stage flavors, but because of the 5-second pause, the coffee grounds remain in a saturated state rather than continuously dripping like in single-pour extraction. This results in higher saturation in the early-stage espresso liquid, leading to a higher extraction rate for the same 40g yield. The smoky flavors become more prominent, caramel flavors weaken, acidity becomes slightly sharp, and there's even some over-extraction.

The segmented extraction produces a softer flavor profile, possibly because most flavors have already been extracted during the initial 15 seconds. The flow after 20 seconds shows lighter color and faster speed, indicating fewer extractable compounds remaining. The 5-second mid-extraction pause increases the saturation of later-stage espresso compared to single-pour extraction, making the flavor more similar to the early-stage liquid. This results in less distinct layering but better balance.

I made a Flat White with each of these espresso extractions.

Single-Pour Flat White

Flavor: Milky aroma, toffee, white chocolate, nuts. Overall flavor is very sweet, more like a toffee latte.

Pre-infusion Flat White

Flavor: Nuts, cream, cookie, woody, rubber notes. Overall coffee flavor is quite intense.

Segmented Extraction Flat White

Flavor: Hazelnut, caramel, almond, cocoa, cream. Overall profile is well-balanced.

When transformed into Flat Whites, the three espresso extractions each revealed distinct characteristics. Most notably, the pre-infusion version, which already showed signs of over-extraction, became even more pronounced when milk was added—the dilution seemed to "release" all the over-extracted flavors.

The segmented extraction Flat White remained well-balanced, as the original espresso was already quite balanced, with rich nutty notes emerging with the addition of milk.

The single-pour Flat White showed the most layering—since the original espresso had rich fruit acids, it became exceptionally sweet when milk was added.

Personally, I prefer the richly layered single-pour Flat White. While the segmented extraction version is also good, considering the stability required for actual café service, I generally wouldn't recommend it for regular use.

Important Notice :

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