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

Today, while discussing pour-over blooming, single-pour extraction, and segmented pouring with colleagues, I started wondering what would happen if those techniques were applied to espresso extraction. Better to test than to wonder, so I headed straight to the bar.

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

Today's Espresso Extraction Experiments

Parameters: double portafilter / 21g of ground coffee / 40g of espresso liquid

Single-Pour Extraction

Technique: extract 40g of espresso straight through, total time 25 seconds.

Espresso flavor: caramel, hazelnut, berry, smoke. The overall flavor is rich and full-bodied, with caramel sweetness in the aftertaste.

Pre-Infusion

Technique: run the pump for 5 seconds, pause for 5 seconds (10 seconds elapsed), then resume extraction. Total extraction time is 31 seconds.

Espresso flavor: caramel, cocoa, lemon acidity. The smoky notes are heavier than in the single-pour shot, and the acidity is prominent too, while the aftertaste sweetness is muted.

Segmented Extraction

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

Espresso flavor: berry, caramel, nut, smoke. The aftertaste carries maple syrup sweetness, and the overall profile is softer.

Of the three, single-pour extraction delivers the most full-bodied flavor with the richest layering. Pre-infusion extracts fewer early-stage flavors to begin with, but the 5-second pause keeps the coffee bed saturated rather than dripping continuously as in a straight shot. That pushes more saturation into the early espresso liquid, raising the effective extraction rate for the same 40g yield: the smoky flavors become more prominent, caramel recedes, the acidity turns slightly sharp - even a hint of over-extraction shows up.

The segmented shot produces the softest profile, likely because most of the flavor was already extracted in the first 15 seconds. The flow after the 20-second mark runs paler and faster, indicating fewer soluble compounds remaining. The mid-extraction pause also raises the saturation of the later liquid compared with a straight shot, making it more similar to the early-stage liquid - so the layering is less distinct, but the balance is better.

Next, I made a Flat White with each extraction.

Single-Pour Flat White

Flavor: milky aroma, toffee, white chocolate, nuts. Very sweet overall - closer to a toffee latte.

Pre-Infusion Flat White

Flavor: nuts, cream, cookie, wood, a hint of rubber. The coffee flavor is quite intense.

Segmented-Extraction Flat White

Flavor: hazelnut, caramel, almond, cocoa, cream. Nicely balanced overall.

Once the milk went in, the three extractions each showed distinct character. Most striking was the pre-infusion version: already showing signs of over-extraction as espresso, it became even more so with milk - the dilution seemed to "release" every over-extracted flaw.

The segmented Flat White stayed well balanced - the base espresso was already balanced, and rich nutty notes emerged with the milk.

The single-pour Flat White showed the most layering: the original shot's rich fruit acidity turned exceptionally sweet once milk was added.

Personally, I prefer the richly layered single-pour Flat White. The segmented version is also good, but given the consistency an actual café service demands, I wouldn't recommend it for everyday use.

FrontStreet Coffee Recommendation

Experiments like these deserve a blend built for the espresso machine, and FrontStreet Coffee's Signature Blend is exactly that: washed Colombia and pulped natural Brazil, medium-dark roasted, expressing nut, dark chocolate, and caramel with crema that rivals café quality. Its nut, almond, and cocoa sweetness shines through milk, making it ideal for flat whites and latte art practice. If you want even deeper crema and body, the FrontStreet Commercial Blend adds a touch of Robusta for thicker, dark-brown crema - the same philosophy behind FrontStreet Coffee's Premium Blend used in this experiment.