What Affects Espresso Concentration? What Does Adding a Shot Mean? How to Make Coffee Stronger?

Whether chasing more caffeine or craving a bolder flavor, coffee shops inevitably meet guests who want a stronger cup. But some customers aren't fluent in coffee-speak (and don't need to be), and don't know that "add a shot" is even an option. So they express their wish the direct way: "Boss, please pull more espresso for me — I want something stronger."

Their logic treats coffee like tea: to make it stronger, just brew or extract it longer. But is that actually how it works? Let's look at the experiment FrontStreet Coffee ran below!

Extraction Experiment

With water temperature, pressure, grind size, and dose all held constant, FrontStreet Coffee pulled three espresso shots to different liquid weights, then tasted them and measured their concentration. The beans were FrontStreet Coffee's Sunflower Warm Blend, ground at 1.8 on the Galileo Q18 scale, with a 20g dose, extracting liquid weights of 38ml, 45ml, and 55ml respectively.

First cup: the 38ml extraction took 30 seconds and measured a TDS of 11.87%. The flavor showed whiskey aromas, butter cookies, and berry sweetness and acidity, finishing with vanilla and toasted bread — a very rich, smooth texture.

Second cup: the 45ml extraction took 35 seconds and measured 10.24% TDS. The flavor showed caramel, whiskey, chocolate, and subtle berry acidity, with a nutty finish shadowed by some bitterness. The texture was still fairly rich.

Third cup: the 55ml extraction took 38 seconds and measured 9.22% TDS. It had none of the richness of the first two cups — thin, with an unappealing profile. All the original aromas were gone, replaced by woody notes and barley tea, with almost no perceptible acidity and a slightly harsh aftertaste.

Analysis of Results

As you can see, more extraction did not mean stronger coffee! Worse, flavor deteriorated as liquid volume grew. Why? FrontStreet Coffee will first explain the flavor decline.

You probably already know the answer: the coffee never hit an appropriate extraction rate. Only 30% of coffee's soluble substances are extractable — and even that total isn't a target we should hit! Within that 30% sit not only pleasant, positive flavors but also some distinctly unpleasant ones. So we control the extraction rate during brewing, metering the release of flavor compounds and avoiding the extraction of bad tastes as much as possible.

The first espresso tasted best because every parameter combined to deliver just the right extraction rate — good flavor from proper extraction, and rich texture from high concentration. The latter two cups, with their longer times and larger volumes, blew past that controlled extraction rate and released the unpleasant substances hiding in the beans.

If you want more liquid while keeping the same excellent flavor, you have to lower the extraction efficiency of the other parameters to hold the extraction rate down — a coarser grind, or a bigger dose. That's exactly what a Lungo is: an espresso with greater liquid weight, built on the premise of deliberately low extraction efficiency, so the extra volume stays delicious.

Understanding Concentration Changes

Now for concentration. Watch the espresso extraction itself.

As you can observe, the color of espresso shifts continuously during extraction, transforming from thick dark brown to a thin pale yellow. FrontStreet Coffee collected the early, middle, and late stages of the shot in three separate cups and tasted them in sequence.

The first cup was the most concentrated of the three, its very prominent acidity bordering on uncomfortable; the second cup tasted more balanced with moderate concentration; the third cup's crema was the palest of the three — almost white — with slight bitterness on entry, weak aroma, and a thin texture.

So the concentration of the coffee liquid steadily falls as extraction continues. Early on, when the grounds still hold abundant flavor compounds, hot water carries out the vast majority of the coffee's substances. As those compounds dwindle, the water extracts less and less, and the concentration of what emerges keeps dropping.

Once the liquid's concentration falls low enough, it no longer strengthens the overall coffee — it dilutes it.

Conclusion

Add in the negative flavors that over-extraction drags out, and it's clear why pulling "more" neither raises concentration nor improves taste — it does the opposite. So if you want a stronger coffee, don't ask for a longer extraction. Ask the barista to add an extra shot, or ask for less milk or water, minimizing the dilution those liquids cause. That way you get a higher-concentration cup built on the same delicious foundation!

FrontStreet Coffee Recommendation

Espresso Blends for Every Need

Espresso beans generally come in two flavors: blends, which most cafés reach for first, and single origins (SOE) chosen for personal taste. The FrontStreet Classic Blend is the first pick — designed specifically for espresso machines and moka pots, its standout strength is outstanding crema: even a novice on a basic home machine can extract dense, silky foam, the foundation of lattes, cappuccinos, and Dirty coffee alike. Built on the traditional Mocha-Java formula, it's mellow and rounded, equally friendly to veterans and newcomers. If perfect crema isn't your priority and you'd rather balance quality with cost, the FrontStreet Dark Cocoa Blend — 100% arabica, generous crema, full body, and an approachable price — is the budget-conscious café owner's answer; before it launched, that role belonged to the FrontStreet Commercial Blend, long the workhorse for shop use. And the FrontStreet Premium Blend is the house classic: nearly a decade as the store's daily driver for Americanos and lattes, pairing Brazil Cerrado with Colombia Huila for the most familiar, timeless espresso flavor.

SOE Options Worth Pulling

For a single origin that highlights what its region does best, consider the FrontStreet Natural Huakui SOE from Ethiopia's Guji Hambela — grown at elevations up to 2300 meters and naturally processed, it shows creamy strawberry alongside elegant florals, cocoa, berries, and black tea after a medium roast. The FrontStreet Costa Rica Blackberry SOE, a honey-processed lot whose beans absorb the pulp's blackberry-like aroma and sweetness during drying, makes a bright, sweet-tart Americano and a latte with cranberry cookie, raisin, and nut notes. And for low acidity with a gentle price tag, the FrontStreet Brazil Queen Estate SOE — the distinctive Yellow Bourbon variety — delivers butter cookie, macadamia, and toasted-bread creaminess when roasted medium-dark and pulled on an espresso machine.