Introduction:Many customers believe that extending the extraction time can make the coffee stronger, but this is actually a common misconception. This article delves into the science behind coffee concentration through experimental data and practical experience, and provides useful extraction tips to teach you how to properly adjust parameters to effectively enhance coffee strength—applicable whether you're using pour over or espresso methods.
"Boss, please extract the coffee a bit longer—I want it stronger."
This is a request often heard by baristas in coffee shops. Many customers hope to achieve a more intense-flavored cup by extending the extraction time. However, according to actual testing and scientific analysis,there is no direct positive correlation between extending extraction time and increasing coffee concentration.
Generally speaking, consumers tend to equate "more liquid" with "stronger taste," but that’s not the case. When extracting with the same amount of coffee grounds and grind size, as the total volume of extracted liquid increases, the concentration of the coffee (i.e., TDS, total dissolved solids) often decreases instead. The following experimental data can help us better understand this phenomenon.
Experimental conditions were as follows: using Sunflower Warm Sun espresso blend beans, grind setting at 1.0 on the Galileo Q18, fixed coffee dose of 20 grams, and extracting three different volumes of coffee liquid—38ml, 45ml, and 55ml—with corresponding extraction times of 30 seconds, 35 seconds, and 38 seconds.
Group 1: 20g of coffee grounds extracted to 38ml of coffee liquid,yielded a TDS of 11.87%,with flavors featuring pronounced berry acidity and sweetness, whiskey-like aromas, and the richness of butter cookies, followed by a vanilla and hazelnut roasted aftertaste. The overall profile was balanced and rich.
Group 2: 20g of coffee grounds extracted to 45ml of coffee liquid,had a TDS of 10.24%,with flavors shifting toward caramel, cocoa, and butter cookies, accompanied by slight berry acidity and whiskey notes. The aftertaste included almond tones and mild bitterness, resulting in a gentler overall impression.
Group 3: 20g of coffee grounds extracted to 55ml of coffee liquid,showed a TDS of only 9.22%,the lowest among the three groups. While the aforementioned flavors were still discernible, the overall performance was flat, dominated by barley tea and woody notes, and even featured a slight throat-burning bitterness upon swallowing—a classic sign of over-extraction.
This shows that, with a fixed coffee dose, as the volume of extracted liquid increases, the concentration of the coffee gradually declines. The reason is thatonly about 30% of the substances in coffee beans are soluble in water,which means that once these flavorful compounds have been fully extracted, adding more water will not increase concentration. Instead, it may release undesirable off-flavors, leading to flavor degradation.
Since extending extraction time and increasing liquid volume don’t help boost concentration, how can you make your coffee stronger? The answer is simple:reduce the volume of liquid extracted—or the amount of water used.
Observe the color of the coffee liquid during pour over or espresso extraction—it changes with the extraction phase, typically from dark to light, and may even appear whitish at the end. This reflects thatthe release of soluble coffee substances is most concentrated in the early stage, and gradually decreases afterward.
In practice, the extraction process can be divided into early, middle, and late stages, with each stage’s liquid observed separately. Early-stage coffee liquid is usually the darkest, most concentrated, and richest in flavor, though it may exhibit more noticeable acidity. The middle stage is relatively balanced, while the late-stage liquid becomes lighter in color, with thinner flavors and even undesirable off-notes.
Therefore, if you want to increase the overall concentration of your coffee,you should reduce the extraction volume of the low-concentration late-stage liquid,meaning reducing the total extracted liquid volume. For example, in pour over coffee, if you’re originally using a 1:15 coffee-to-water ratio, try adjusting it to 1:14 or even 1:13. With the same coffee dose, reducing the amount of water poured will effectively raise the concentration.
It’s important to note that reducing water volume can increase concentration but may also lower overall extraction efficiency. If you wish to maintain good extraction while increasing concentration, you’ll need to appropriately adjust other parameters—such as increasing grind size, raising water temperature, or extending extraction time—to ensure flavor compounds are effectively released. This principle also applies to espresso preparation.
Additionally, the above methods mainly apply to adjusting the concentration of pure black coffee. If you’re making milk-based drinks like lattes or cappuccinos, simply increasing the strength of the coffee liquid won’t necessarily make the coffee flavor stand out more in the overall beverage, because the volume of milk or other ingredients still accounts for a large proportion.The absolute quantity of coffee material hasn’t increased.
To make the coffee flavor more prominent in milk-based drinks, the correct approach is toincrease the amount of coffee grounds used or reduce the proportion of milk and other ingredients,thereby increasing the ratio of espresso in the entire drink—this is how you truly enhance the expression of coffee flavor.
The above content is compiled by CoffeeHunters, a coffee news website.
