Brewing espresso is especially fascinating because it requires a more complex process of extraction than other ways of preparing coffee. The varying pressure of espresso extraction is what gives it its distinctive flavor.
This article looks into what impacts extraction in brewing and how that translates to the flavor of the drink. For those of you who need help with brewing espresso, check out our article on “How to Make Espresso Using an Espresso Machine”. That piece is a great beginning point for anyone who desires to start brewing espresso in the comfort of their own home.
If you’re a perfectionist and are striving for that ideal shot, you could look more closely into this tutorial to learn how each adjustment to a coffee recipe changes the flavor.
What Is Extraction?
Extraction refers to the means of obtaining the flavors from coffee grounds that are later put into the water. How long you brew the drink, the heat of the water, the coarseness of the grind, and the darkening of the roast can all influence how the espresso is extracted. The solubility of coffee is what is used as the basis for its extraction process.
Many of the elements present in coffee can be dissolved in water. It’s like sugar or table salt. You put them in water and they will dissolve. However, these compounds dissolve faster or slower in water. Certain substances can only dissolve when it is hot, and other substances evaporate rapidly when it is too hot.
Coffee beans are about 28% water-soluble. This is the amount of coffee you can extract from a single roasted bean into your cup. The remainder of the coffee bean’s composition consists of cellulose and other plant material. We don’t intend to take out the entire 28%, because some of it is unpalatable.
The process of making espresso is designed to pull the largest amount of good qualities out of the beans and put as few bad components in the drink as possible.
What Impacts Coffee Extraction?
Grind Size
The most important factor that influences the flavor of your coffee is the size of the grounds. A grind with larger granules results in less area of the coffee coming into contact with the water, thus creating a less fine overall consistency. The coffee must be steeped for more time to get a good taste, or else it will end up lacking in strength, and not fully infused.
Coffee that has been ground to a finer consistency has a greater surface area, thereby allowing the flavors to be drawn out at a faster rate than if it were ground coarsly. This means the coffee can quickly become over-extracted.
It is essential to choose a grinding size suitable for the specific brewing method you are using, and to ensure that a high-quality burr grinder is used. These measures make sure that the coffee beans are ground to an equivalent dimension, leading to a more even and stable taste.
Brew Ratio
The proportion of coffee to water is a basic point to think about, yet it has a massive impact on the extraction of taste. If you don’t use enough coffee grounds, you won’t be able to achieve a strong, full-bodied taste. For making coffee using the pour-over, drip, or French Press methods, it is advisable to start with a measurement of 1 part coffee to 15 parts water. One gram of coffee should be mixed with every 15 grams of water. The exact amount of this item can be changed as much as you like until the flavor is just right for you.
For espresso-style brewing, the ratio is typically much lower, about 1:2.
Brew Time
It is important to pay close attention to how long the coffee is in water to make sure that it is pulled out at the correct time; this will give you the best flavor while avoiding any unpleasant bitterness. It is typically true that the more finely the coffee is ground, the less amount of brewing time is required. For espresso that is ground up very finely, the length of time it should be extracted is between 25-30 seconds. For French Press, with its large, chunky grind, you need to let the coffee steep for four minutes.
Bed Depth
The bed depth when making coffee is the height of the coffee grounds when they are positioned to be immersed in the water. If the bed depth is not deep enough, then liquid can seep through small cracks and crevices resulting in an under-brewed, and consequently sour, cup of coffee. If the depth of the bed is too deep, then the amount of time that the water has contact with the bed will be too lengthy, resulting in the water tasting bitter.
Be certain to adhere to the directions of the maker of the product when brewing coffee, and make certain to use a coffee-making device with a deep enough depth to facilitate the method you would like to use.
Water Temperature
Using hotter water when brewing coffee causes the particles in the coffee grounds to become agitated, allowing the flavor to be extracted more readily. If the temperature of the water is not hot enough, then the coffee will come out tasting watery and lacking flavor. The optimal temperature for making coffee ranges from 91-99°C (195-210°F). Generally, a darker roast requires a lower heat setting, while lighter roasts require higher temperature levels.
It’s worth noting that there is an answer to the difficulty with the water temperature. It is possible to make coffee using cold water, known as cold brew coffee. For best results, this type of coffee should be left to steep for a time period of between 12-24 hours. By extending the time it takes to extract, it is possible to address the issue of the cold water.
Water Quality
The type of water used to make coffee can affect the level of extraction. Contaminants in the water can influence the pH level, acidity, and hardness of the liquid, all of which may have an influence on the removal process. The hub of this piece is not about how the ingredients in the water influence extraction, but if you’d like to find out more, we’ve included a terrific article referencing that. The best way to guarantee a pleasant cup of extracted coffee is to just use filtered water.
Agitation
The basic function of coffee extraction comes from diffusion. The flavor molecules in the coffee dissolved into the water as the two came into contact, causing them to move from a space where they were heavily concentrated to the water around them. The process of diffusion is the way water eventually reaches balance, though it takes quite a while.
This is where agitation comes into play. If you stir the coffee, this allows more of the water to touch the coffee and makes the diffusion process go faster. If the coffee is not stirred after the water has been poured in, pockets of air may be encased inside of it, leading to an inconsistent brewing outcome.
Brew methods such as Aeropress and French Press require stirring with a stirring wand in order to mix the coffee, creating a more even extraction.
Over vs Under-Extraction
If the coffee has a sharp, shallow, parched taste and is deficient in complexity of flavor, it has been brewed for too long. It is probable that the brewed coffee tastes bad because it was left to steep for too long, the grind size was too small, or the water temperature was too high. At this point, the majority of the sugars that give the coffee its intense, sugary taste have been decreased, so the beverage you’re left with is not sugary at all.
Adding some kind of creamy component such as milk, sugar, or a sweetener is an effective way to get rid of the harsh aftertaste of an overly strong cup of coffee.
If the coffee has a more tart or intense flavor, it has not been brewed correctly. This is due to the insufficient amount of time the coffee has been immersed in the water for the intricate starches to start splitting down into simple sugars. This may have been caused by the amount of time that you took to brew the coffee being insufficient, the temperature of the water being too low, or the grind size used being too large for the brewing technique.
A system has been developed by coffee experts to rate a cup of coffee according to the ratio of desirable and undesirable compounds that are extracted. This system categorizes a cup of coffee according to whether it has been properly extracted, insufficiently extracted, or excessively extracted.
Soluble Solids Extraction Order
No matter how it is prepared, water always draws out the flavor elements in this sequence: fats and acids first, then sugars, and finally plant fibers. It is possible to detect if coffee has been brewed for too long or not long enough mostly based on its flavor.
The initial substances obtained from coffee are acids and fats. Acids, creating a sour flavor in coffee, are the most basic of compounds. Water readily blends into the coffee. A number of the delicate fragrances, for example, the flowery and the fruity aromas are being isolated currently. Acidity and subtle flavors are extremely critical for making a great cup of coffee, as they are what give it the unique taste.
At nearly the same moment, we pull out the oils from the coffee. The oils in coffee add body to your cup. Fats repel water and separate from the grounds in coffee quite easily. Espresso drinks rely heavily on them, unlike filter coffee. Without fats, some of the heavier aromatics will lack. Without coffee oils, there would be no crema.
Sugars are extracted next. It takes more time and effort for water to completely dissolve them. The sweetness in an espresso is due to the sugars present in the beverage. This is what creates the classic espresso flavor.
Eventually, the plant fibers keeping the ground coffee in place will disintegrate. We want to stay away from the fibers that have a bitter, dry taste. Using a little bit of the spices can give our cup some flavor, but if we add too much the coffee will be ruined.
Extractions Yield vs. Total Dissolved Solids (TDS)
The amount of soluble substances that are pulled from the coffee beans is called the extraction yield, while the TDS is the strength of those caffeine solubles found in the prepared beverage.
The result of the extraction can be seen in terms of how well the substance dissolved, and the total dissolved solids giving an indication of the amount of solvent used.
A ristretto has a higher solids concentration but less liquid than a lungo. A lungo brewing method is more effective in taking out the positive components from the coffee beans than a ristretto process. Nevertheless, lungo will draw out more sorrowful compounds compared to ristretto.
Extraction and Coffee Strength
The quality of the brewed espresso is the deciding factor, and the amount of espresso that is brewed is also of equal importance. I’m not referring to the quantity of caffeine in the beverage, but rather the concentration of solids that have been dissolved in the liquid.
The amount of caffeinated flavor in coffee is determined by the proportion of ground coffee to water used in the brewing process. Too little water will make your coffee taste muddy. If you add an excessive amount of water, your coffee will have an unsatisfying, watered-down consistency.
Strength is in direct relationship to extraction. If you want an intense cup of coffee, you can use a smaller amount of water to achieve a stronger brew. It’s not the best idea, though it is possible.
A disadvantage of espresso coffee is that the intensity of the brew can overpower its subtler tastes. The more intense the alcohol content in a beverage, the harder it is to identify particular tastes. Sugars and oils in espresso tend to overpower the subtle floral and fruity flavors.
Coffee Strength/Concentration vs Over-Extraction
Some home baristas confuse coffee strength with over-extraction. If the coffee is too intense, simply mix some water in to dilute it and that should bring it back to normal. Conversely, if brewed for too long, a cup of coffee will still be overly bitter even when mixed with water.
Over-extraction is a bit contextual and even subjective. I am mindful of this, so I use the term carefully. When making espresso, what is considered to be the correct amount of extracted flavor is thought to be too much when it comes to drip coffee.
Some people love their coffee more stronger than others. But if we make a stronger beverage, that is what we will do – make a stronger drink. We don’t take too much from that cup, but we do get a bit more out of the grounds.
Did we extract too many tannins from the grounds? Then yes we did over extracted it.
It’s much easier to evaluate espresso compared to drip coffee or French press. We have to take care to measure out between 20 and 25 seconds when making a lungo or a ristretto to prevent over-brewing or not brewing enough. This is the reason why coffee shop lungo drinks can either be too weak or too strong. They cannot adjust the grind size. The grinder can be adjusted to make either a regular cup of coffee or an espresso-like brew, depending on the cafe.