When it comes to coffee, you will often hear people request a strong cup. Typically, when people refer to a type of coffee strength, they assume it refers to how the coffee is roasted: light roast, medium roast, or dark roast. However, it might surprise you to discover that the type of coffee roast does not determine the coffee strength; the brewing process does.
Coffee Strength in Numbers
Coffee strength is developed during the brewing process. This is excellent news, especially for those that brew any type of coffee at home, because you are in charge of how strong or weak your coffee is each day. With this knowledge, you now know that you are in control of how your day begins, and that is a glorious power to hold.
We’re going to get technical here for a minute to break down how coffee strength is determined in different types of coffees. We measure coffee strength using the unit Total Dissolved Solids (TDS) in percentages. Total Dissolved Solids will indicate how concentrated or watery the coffee is. The more concentrated the coffee, the stronger the cup, the waterier the coffee, the weaker. The amount of dissolved compounds in a cup of coffee equals the Total Dissolved Solids measurement, which then gives us our coffee strength.
Coffee strength, much like coffee flavor, will be up to your taste buds. When brewing coffee at home, you allow yourself the luxury of trial and error to determine the ideal coffee strength and if you want to extract more or less in the future.
Measuring Strength at Home
You can absolutely measure the exact strength of your coffee at home if you are willing to spend the money, but for those who love to explore and play, it is worth the investment. The tool for measuring coffee strength is called a refractometer, and it’s used to measure the water content of liquids.
Until recently, refractometers were used in laboratories to test the composition of gemstones and for medical purposes such as testing plasma levels. However, lovers of all types of coffee are always searching for ways to redefine and elevate the world of coffee and improve the overall culture. The coffee refractometer has a different design than the scientific refractometer, but using a medical device to boost your coffee game is an excellent way to redefine how we view coffee.
TDS Breakdown, the Ideal Total Dissolved Solids for Each Type of Coffee
The most popular brewing methods have similar TDS requirements, with the glaring exception being espresso. It makes perfect sense if you think about what constitutes a higher TDS level.
The espresso is a highly concentrated shot intended to give the coffee drinker an instant caffeine boost.
- Pour Over - 1.2-1.5% TDS
- Cold Brew - 1.4-1.6% TDS
- French Press - 1.4-1.7% TDS
- Espresso - 8-12% TDS
Another way to look at TDS percentages is, for example, a standard pour-over coffee strength of 1.5% means the coffee itself is 98.5% water.
So, to determine the extraction percentage for the type of coffee, we would use the below formula:
Brewed coffee weight (grams) x TDS / Ground coffee weight (grams) = Extraction percentage
As mentioned above, the most crucial test for identifying the ideal TDS or extraction percentage for coffee strength is your personal taste preference. Using mathematical formulas to determine the extraction percentage takes something that seems arbitrary, like the taste, and gives it a literal value.
Total Dissolved Solids is how we measure the concentration of different types of coffee. But what is the method to reach the Total Dissolved Solids? Extraction. Extraction is the action of hot or cold water being poured over ground coffee beans. When water is poured over ground coffee beans, caffeine, carbohydrates, acids, lipids, and other beneficial compounds are literally extracted from the coffee beans. The extraction process is how coffee strength is determined.
The formula for coffee extraction is:
Extraction Yield % = Brewed Coffee (g) x TDS (%) / Dose (g)
Extraction, in simpler terms, is the brewing process. The brewing process for cold brew is significantly different than that of espresso or pour-over in the same way the coffee strength of each of these is different. Not only does the water temperature vary, but the brewing and extraction time is wildly different for each type of coffee.
If you're not familiar with the cold brew process, the coffee beans are steeped in cold water for up to 24 hours before it’s time to drink it. On the flip side, an espresso takes 30 seconds to make.
So, what factors play into a successful and tasty extraction process to obtain optimal coffee strength and flavor?
- Water-to-coffee ratio
- Coffee bean grind size
- Coffee roast level
This will vary depending on your brewing method and the type of coffee you are making since each brewing method has a different extraction processing time.
The ratio for espresso will be one part espresso to two parts water. The ratio for cold brew is typically one part coffee to eight parts water. However, those that prefer a more concentrated cold brew will make one part coffee to four parts water. The ratio for drip coffee or pour-over is one part coffee to 17 parts water.
Coffee Bean Grind Size:
The grind size is an integral part of the coffee brewing process. Newer coffee drinkers might not be aware of the impact an appropriate grind size plays in different types of coffee and the strength of the coffee. However, each brewing style has a specific grind size to ensure your coffee is brewed to perfection.
- Under Extraction
- Ideal Extraction
- Over Extraction
Under-Extracted Coffee Grounds:
Brewing coffee is absolutely a skill. If coffee is under-extracted, it will taste sour, salty, or sharp, and it will also lack the necessary sweetness. Under-extracted coffee results from the water not having enough time to fully break down the sugars in the coffee grounds to balance with the acidic tones.
For example, using coarsely ground coffee to make an espresso type of coffee drink would result in an under-extracted coffee. This is because the surface area of the coffee grounds would not be big enough to allow the water to pass through quickly enough, preventing the brewing process from fully extracting the flavors. This under extraction would create a weak espresso that lacks flavor.
Each type of coffee brewing process has a specific grind size to fully bring out the natural flavors of the coffee bean. The quicker the brewing process, the smaller the size of the coffee grind. Espresso brewing clocks in at 30 seconds and therefore uses a fine grind. On the other hand, cold brew takes 24 hours and uses coarse coffee grounds.
The more time the coffee grounds spend in the extraction process, the larger the grind size. Extraction is all about finding balance to retain the integrity of the coffee bean and the roasting process.
Over-Extracted Coffee Grounds:
This is the exact opposite of under-extracted coffee grounds. If you were looking to brew a type of coffee like a pour-over, drip, cold brew, or French press coffee, you would need medium or coarse ground coffee beans. However, if you were to use the fine espresso grind, it would lead to a bitter, dry, and astringent tasting brew.
Finely ground coffee beans have more surface area. The more surface area, the quicker the water can dissolve and extract the flavor from the coffee. The fine grind intended for a 30-second espresso brewing process would be completely drained during a 24-hour cold brewing process.
While an under-extracted coffee brewing process will lead to a weaker tasting coffee, over-extracted coffee grounds will not lead to an increase in coffee strength. The weaker coffee from a too-large grind size is low in flavor due to an incomplete brewing process. Yet, using too small of a grind will only serve to strip the coffee grounds of their natural flavors and create a bitter taste in your mouth that you hope to soon forget. The grind size you use is directly related to the type of coffee extraction process you are doing.
Does Coffee Flavor Affect Strength?
All coffee roasts are created equal, at least in terms of caffeine. However, all types of coffee have different flavor profiles. For some coffee drinkers, flavor makes them think of pumpkin spice or French vanilla coffee or adding flavored creamer. However, when speaking of the flavor profile of coffee, we are referring to their roast level.
Flavor Guide Scale for Coffee Roasting Levels:
- Dry and crisp
- Dry and fruity
- Dry and full-bodied
- Smooth and mellow
- Smooth and rich
- Rich and fruity
- Rich and nutty
- Rich and winey - chocolate undertones
- Rich and full-bodied
- Strong Italian flavor
A light roast coffee does not indicate coffee strength or weakness; a light roast is an indicator of how long the coffee beans have been in the roasting machine.
The longer the coffee beans roast, certain flavors are almost entirely roasted away while others are brought to the forefront. Lightly roasted coffee will retain the majority of the natural coffee bean flavors. There will be an emphasis on floral and fruity notes.
If you are looking for a full-bodied coffee that is crisp and fruity, light roast coffee beans are what you want. However, if you want these flavors but you are looking for a more elevated coffee strength, brew light roast coffee beans as an espresso.
Medium and Medium-Dark Roasts:
Medium and medium-dark roast coffee beans are popular. Many people assume a medium roast will be a middle ground between light and dark roast. However, it has its own unique flavor profile due to its roasting time.
Medium roast coffee beans retain some of the coffee beans' natural flavors; however, they have a more sweet and caramelized flavor due to extra roasting time. The medium roast was the coffee world's first introduction to experimenting with roast styles.
Dark and Very Dark Roasts:
Dark roast coffee is the original roasting style for all types of coffee. The longer roasting time strips the majority of the natural coffee bean flavors and presents a deep chocolatey flavor and aroma. Compared to the fruity, light roast flavor, this chocolate flavor is why the common perception is that dark roast is stronger when in actuality, it is not.
A dark roast coffee made using the pour-over brewing method will be weaker in coffee strength and contain less caffeine than a light roast coffee espresso shot. However, the coffee beans, after roasting, have a negligible difference in their amount of caffeine, so you can enjoy your favorite type of coffee roast without sacrificing the kick of caffeine you need.
The Connection Between Coffee Scent and Taste
Even if someone doesn’t drink any type of coffee, we all appreciate its aroma. Walking into a coffee shop, coming downstairs into the kitchen while the morning coffee is brewing—sometimes the scent alone is enough to trigger a caffeine-like reaction in our bodies.
Our senses of taste and smell are closely linked. In fact, when we are eating or drinking any type of coffee or other beverage, our receptors send both the taste and scent to our brain, and those two components are intertwined together to create our brain's reaction. This integration of scent and taste is what enables us to appreciate the food and drinks we enjoy.
You have probably noticed at some point in your life that scent also has an undeniable connection with memories. For example, clove and cinnamon scents and flavors are typically linked to the cold-weather holiday seasons. In addition, most millennials are immediately transported back to their childhood with specific Bath and Body Works and Victoria's Secret scents.
Finding a scent, much like the flavor of coffee, is comforting and can become part of a morning routine that encourages you to begin your day in a positive way. When we smell a scent, it goes directly to the olfactory bulb in our brains. The olfactory bulb is connected to both the amygdala and the hippocampus sections of our brains. The amygdala is responsible for emotional processing, and the hippocampus is responsible for memories.
Coffee Strength in Numbers
Our coffee strength is not found in the types of coffee roasts we use; it is a direct result of the extraction process and the Total Dissolved Solids. The strength of our coffee is found within—within the brewing process we choose. Every day, you have the ability to be in control of the type of coffee you want, the coffee strength you desire, and the flavor profile you love. You do not have to sacrifice flavor to obtain the caffeine kick you need to get through your day.