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

Whether seeking more caffeine intake or desiring a richer coffee flavor, coffee shops inevitably encounter guests with higher demands for coffee concentration. However, some customers are not familiar with the coffee domain (nor do they need to be), and are unaware of the option to add a shot to their coffee. Therefore, they often express their desire for stronger coffee by saying: "Boss, please extract more espresso for me, I want to drink something stronger."

Because these friends believe that coffee is like tea – to make it stronger, you simply need to brew/extract it for a longer time. But is this really the case? Let's look at the experiment conducted by FrontStreet Coffee below!

Extraction Experiment

Maintaining constant water temperature, pressure, grind size, and coffee dose, FrontStreet Coffee extracted three espresso shots with different liquid weights. Through tasting and concentration measurement, let's see how the concentration and flavor of these coffees change! The coffee beans used 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 espresso extraction took 30 seconds, with a measured TDS value of 11.87%. The flavor featured whiskey aromas, butter cookies, and berry sweetness and acidity, with a finish of vanilla and toasted bread notes, presenting a very rich and smooth texture.

Second cup: The 45ml espresso extraction took 35 seconds, with a measured TDS value of 10.24%. The flavor featured caramel, whiskey aromas, chocolate, and subtle berry acidity, with a nutty finish but accompanied by some bitterness. The texture was relatively rich.

Third cup: The 55ml espresso extraction took 38 seconds, with a measured TDS value of 9.22%. It completely lacked the richness of the first two cups, feeling very thin. The flavor profile was unappealing, with all original aromas gone, dominated by woody notes and barley tea, with almost no perceptible acidity and a slightly harsh aftertaste.

Analysis of Results

As can be seen, although more coffee was extracted, it didn't become stronger! Not only that, but the coffee's flavor also deteriorated as the liquid volume increased. Why does this happen? FrontStreet Coffee will first explain why the coffee flavor becomes progressively worse.

As everyone probably knows, this is because the coffee didn't achieve an appropriate extraction rate. Only 30% of coffee's soluble substances are extractable, and although this is the total amount, we don't need to extract all of it! This is because within these 30% of substances, there are not only pleasant positive flavors but also some unpleasant negative tastes. Therefore, we need to control the extraction rate during brewing, limiting the release of coffee's flavor compounds and avoiding the extraction of unpleasant flavors as much as possible.

The reason the first espresso tasted best is that the extraction rate provided by each parameter was just right, so the resulting espresso not only had good flavor due to the appropriate extraction rate but also possessed a rich texture due to its higher concentration. In contrast, the latter two cups, due to increased extraction time and liquid volume, broke the originally controlled extraction rate, releasing some unpleasant substances hidden in the coffee beans.

If we want to increase the liquid volume while maintaining the same excellent flavor, we need to reduce the extraction efficiency of other parameters to limit the coffee's extraction rate. For example, by adjusting to a coarser grind or increasing the coffee dose. This is precisely what Lungo is – although it's an espresso with greater liquid weight, the premise is that the extraction efficiency is not high, allowing for more liquid while maintaining deliciousness.

Understanding Concentration Changes

Now let's discuss concentration. Let's observe the espresso extraction process.

As can be observed, the color of espresso continuously changes during the extraction process, gradually transforming from the original thick dark brown to a thin pale yellow. FrontStreet Coffee used three separate cups to collect the early, middle, and late stages of espresso extraction and tasted them in sequence.

The first cup of coffee liquid tasted the most concentrated among the three, with very prominent acidity that was somewhat uncomfortable; the second cup tasted more balanced with moderate concentration; the third cup's crema was the lightest in color among the three, even appearing somewhat white. It had a slight bitterness on entry, weak aroma, and a thin texture.

As can be seen, the concentration of coffee liquid gradually decreases as extraction continues. This is because at the beginning, when the flavor compounds in the coffee grounds are most abundant, we extract the vast majority of coffee substances initially. As these coffee compounds gradually decrease, hot water can carry out less and less, resulting in progressively lower concentration of the extracted coffee liquid.

When the coffee liquid concentration drops to a certain level, it not only fails to strengthen the overall coffee but actually dilutes it.

Conclusion

Combining the negative flavors brought by over-extraction, we can understand why extracting more doesn't increase coffee concentration and even makes the coffee taste worse. Therefore, if friends want to make their coffee stronger, why not ask the barista to add an extra shot to the coffee, or reduce the amount of milk or water added, minimizing the dilution effect these liquids have on coffee concentration. This way, you can enjoy coffee with higher concentration based on the original foundation!

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473