The drip coffee method is the most common brewing method used by average coffee drinkers. This is due to the convenience and quick coffee-making ability of an automatic drip machine without needing a lot of expertise.
What is Drip Coffee?
An automatic drip coffee maker prepares a hot drip coffee by heating the water and dripping it over the coffee grounds placed inside the filters using thermally induced pressure. The water extracts the solubles from the grounds and flows to the coffee mug or carafe placed below.
Drip coffee makers are available in a wide range, from very cheap and single-function units to very expensive multifunction units. Avid coffee lovers mostly prefer other brewing methods over drip coffee. Drip coffee is largely for those who are looking for speed and convenience.
Percolation & Extraction in a Drip Coffee
The percolation and extraction dynamics of drip coffee can be divided into two phases.
The hot water is showered onto the bed of coffee grounds, wetting them. This leads to a rapid release of the absorbed carbon dioxide by the ground coffee beans. The released carbon dioxide gas acts like a repellent for water and tries to slow down further wetting and flow of water through the grounds.
Any flowing liquid takes the path of least resistance and, in the process, removes the solids from the coffee grounds before flowing down. Some part of the water is absorbed by the ground coffee, which swells as a result.
The initial portion of the extracted coffee is more concentrated and viscous as it carries more solids. it gradually dilutes as extraction slows down in the later part, and more water finds its way to the extract. You can consider that extraction happens in various subphases.
- Solids at the surface of the grounds are washed off into the coffee drink
- Water drives out gases and enters the pores of the coffee bean ground particles, making them swell.
- Solids within the particles start dissolving, and these dissolved solids diffuse from the areas of higher concentration to low concentration, i.e., to the particle surface and then to the coffee solution.
During the brewing process, water is added from the top continuously and keeps diluting the liquids, gases, and ground coffee. In the upper portion, the added water has a lower concentration of solids. Hence the diffusion late is highest there.
The diffusion rate slows down near the lower bed due to the high amount of solids in the drip coffee brewing coffee there. Hence there is always an uneven extraction, with more solids coming out from the upper bed in comparison to the lower bed.
Drip Brew Coffee Parameters
The drip coffee brewing standards recommend maintaining the main parameters at
- Brewing Ratio is 1:18, which means 3.75 oz coffee grounds in 64 fl oz water.
- Water Temperature: Between 195 °F to 205 °F.
- Total Dissolved Solids (TDS): 1150 to 1350 ppm.
Solubles Yield, Brew Strength, and Flavor
As you may know, the solubles yield of the different brewing methods is the ratio of the mass of the soluble solids in the coffee to the original mass of the coffee grounds. It represents the percentage of solids extracted from the grounds that are dissolved in the freshly brewed coffee.
The brew strength is simply the concentration of the solubles in a given cup of drip coffee. If you keep the original mass of coffee as same, a higher brew strength means more dissolved solids. The yield and brew strength are affected by the grind and the brewing ratio.
The solubles dissolve in the water at their own rates. The combination of different solubles in the brewed coffee gives it a distinct flavor profile.
If the brew strength is low, you will most certainly have a higher concentration of the fast-dissolving compounds, which tend to be acidic, sour, fruity, and bright. Coffee drinks with higher brew strength will start to have slower dissolving compounds which make the coffee less acidic, sweeter, and tend towards caramel flavors.
You must try to have as much uniform grind as possible to get the best coffee cup by drip brewing. Else, you will get portions of over-extracted and under-extracted coffees. It is recommended to have a medium grind to brew drip coffee with a median particle size of 600 microns. The effect of varying the grind size and brew ratio on the brew strength is as follows:
- Finer grind results in an increase in yield and strength.
- Decreasing the brew ratio, i.e., increasing the water proportion, increases the yield while decreasing the strength.
- Making finer grind and decreasing the brew ratio: An increase in yield. The grind can be adjusted to keep the strength the same.
- A Coarser grind decreases the yield and strength.
- An increase in brew ratio (lesser water) decreases the yield and increases the strength.
- A coarser grind and an increase in brew ratio result in a decrease in yield. However, the grind size can be altered to maintain strength.
Brewing Water Temperature
As stated earlier, the optimum brewing temperature is between 195 °F to 205 °F. The optimum temperature depends on the degree of roast, desired flavor profile, and brewing ratio.
- Higher temperatures have higher extractions as compounds are more soluble at increased temperatures.
- The acidity, bitterness, and body increase with temperature.
- Relative concentrations of solubles change with water temperature.
Effect of Turbulence
As stated earlier, turbulence is a factor that has an impact on the quality of coffee from drip coffee machines. It is caused by the release of carbon dioxide gas by the grounds on pouring hot water over them.
Turbulence slows down the flow of water, delays wetting and produces froth on wet grounds. Too much turbulence can lead to over-extraction. On the plus side, it lifts and separates the particles to allow the uniform flow of water and even extraction. If the particles do not move due to the turbulence, the spray from the drip coffee makers will fall on the same patches of ground coffee and result in non-uniform extraction.
The beans roasted many days ago have less turbulence and require a finer grind, while the freshly roasted coffee grinds cause more turbulence and must be towards the courser side to compensate. Of course, the baristas in your local coffee shops take care of these aspects while brewing.
What makes Drip Coffee Different?
As you have seen by now, the drip coffee maker does not create pressure like espresso machines but simply drips the hot water over the grounds. Hence the yield and the brew strength are considerably lower compared to an espresso coffee.
In addition, the paper filters used by the drip coffee makers do not allow the oils and essences to pass through them. Metal filters do not remove them.
What Is The Caffeine Content Of Drip Coffee?
As per Healthline, an 8 fl oz cup of drip coffee contains 95 mg of caffeine on average, with the usual range being 70 to 140 mg.
As you know, the actual caffeine content depends on the type of beans, their blend, brew ratio, grind, brewing time, etc.
How Many Calories Are In Drip Coffee?
A simple drip coffee without any additives contains just 2 calories in every 8 fl. oz of drink. In any coffee drink, the calories come from milk, cream, sugar, syrup, or other additives that you may use.
How To Prepare Drip Coffee?
You can prepare drip coffee in any automatic drip coffee machine that you have. In addition, you may need a weighing scale, a coffee grinder, and a disposable coffee filter. The steps are outlined below:
- Weigh the coffee grounds on a weighting scale as per the ratio (1:18). You can increase or decrease the quantity to suit your taste.
- Grind your coffee beans to the recommended grind size of 600 microns. You may need to adjust it depending on the freshness of the roast to account for turbulence. In addition, if you are making a single cup, you may go in a slightly finer grind. Go a bit coarser if the brew quantity is more.
- Fill the coffee maker with fresh water with low mineral content.
- Next, set up the paper filter. You must flush the paper filters and the brew basket with hot water before use. This will get rid of any odors that the paper might have absorbed during storage. The process also removes any residue from the brew basket and pot and preheats them.
- Load the filter with the grounds and shake the basket to level the grounds. Slide the brew basket gently into the machine.
- Select the number of cups, brew temperature, brew strength, and other optional settings like pre-infusion, etc.
- Press start to begin the brewing process, and let the machine make drip coffee for you.
Importance of Stirring
As stated in earlier sections, the spray head may favor certain areas, and maximum extraction happens at the top of the coffee bed. A liquid acts as a better solvent at higher temperatures, with low concentration and viscosity.
Stirring makes the extraction more even and improves the brew strength and body, reducing the bitterness at the same time. Some machines provide easy access to the grounds. Stir your grounds with a large spoon 5 to 10 seconds after the beginning of the brew cycle, wetting all the grounds. Repeat the process after the spray head stops.
The initial stir makes the extraction uniform through simultaneous wetting of the grounds, ensuring uniform temperature, minimizing the channel formation, and starting the diffusion process early in the bottom bed. The extraction slowly moves again to non-uniform mode after the first stir but is substantially more uniform than if no stir had been provided.
The second stir after the spray head stops makes the concentration of solubles uniform and facilitates their extraction, as part of them have moved to the top of the bed. You will need a slightly coarser grind if you intend to carry out stirring.
Drip Coffee Vs. Pour Over
The pour-over coffee and any filter coffee, for that matter, is prepared in much the same way. The difference lies in that it is one of the manual coffee brewing methods that gives you control over the entire process.
It uses a pour-over cone that supports a cone-shaped filter and coffee grounds. The filter can be made from paper, metal, or cloth.
As you might have guessed, the other steps are similar to the drip coffee except for the pouring of water.
- Add about 50 grams of water, or twice the weight of your grounds, and wait for about 45 seconds to allow for the blooming, which involves the release of the trapped carbon dioxide.
- Pour the remaining water slowly onto the grounds taking care to pour over the grounds and not on the walls. Occasionally swirl the brewer to mix the grounds with water. You can pour the water after the bloom in two or three rounds.
- Hold the kettle at a fixed height, and pour gently with a vertical stream.
- The pour-over method allows you to carry out stirring to have better extraction, as explained above.
What Are The Main Features Of A Good Drip Coffee Maker?
The main features of the best drip coffee makers are
- The Programmable Brewing Options: Number of cups, amount of water, prewet percentage, prewet delay, brewing time, bypass, brew volume, and temperature. Consider the complexity of making the settings if you are uncomfortable with many menus and submenus.
- Thermal Carafe Vs Hot Plate: Thermal Carafes are used to keep the coffee warm for some time. The area between its inner and outer walls is vacuum sealed to prevent loss of heat. The hot plate will keep your coffee warm but also alter its flavor, consume energy, and poses a fire risk.
- The SCAA Certification: These machines brew coffees that meet the Specialty Coffee Association standards with respect to the brew ratio, temperature, turbulence, etc.
What Are The Benefits Of Drip Coffee?
Drip coffee is favored by a large number of people who have a preference for a mild coffee taste and value simplicity, ease of preparation, and convenience over the complexity of other methods.
In addition, the drip coffee machines give you the option of making coffee in bulk in a single brew cycle.
Can you Make drip coffee in cold water?
A cold brew is traditionally prepared by mixing a much coarser grind with cold or room-temperature water, allowing them to steep for 12 to 24 hours.
While cold drip is possible but it is a complex process requiring a drip tower and takes between 3 to 12 hours.
Drip Coffee Vs French Press
French coffee has a fuller body than the coffee prepared by the drip methods, as the paper filters do not trap the oils and the other essentials. In addition, the extraction in the French press method has more uniform extraction as it is an immersion brew where the contents are immersed and steeped in the water.
Drip Coffee Vs Americano
Americano is basically an espresso-based drink where hot water is added to the shots to dilute its strong flavor and taste. Water at 195ºF to 205ºF temperature is poured over a regular espresso shot in a 2:1 ratio. Hence americano inherits all the other features of the espresso, with a reduced concentration and more bitterness.