Make The Perfect Coffee Every Time with Chemistry

You already ditched instant coffee, and you go through the tedious process of making your own coffee. But sometimes you get it right, but sometimes you don’t. No worries because coffee brewing, at its core, is a scientific art.

It's a daily ritual that combines precise measurements, timing, and a bit of chemistry to transform ground coffee beans and water into a delightful beverage. If you’re new to coffee making, you’ve come to the right place. Let's dive into the essentials for making the perfect cup of coffee every single time.

What You Need:

Coffee Beans (of course): Freshly roasted, high-quality beans are non-negotiable. The fresher the bean, the better the flavor.

Digital Scale: Precision is key in chemistry, and coffee making is no different. A digital scale ensures accurate measurements of coffee and water.

Burr Grinder: Uniformity in coffee grounds size is crucial for even extraction. A burr grinder provides consistent grounds, unlike a blade grinder.

Thermometer: Temperature affects extraction rates. Too hot, and you'll over-extract, leading to bitterness; too cold, and under-extraction makes your coffee weak.

Gooseneck Kettle: Control over pouring speed and precision matters in the extraction process. A gooseneck kettle gives you that control.

Filtered Water: Coffee is 98% water, so its quality cannot be overlooked. Filtered water can significantly improve the taste of your coffee.

Chemex, French Press, or Espresso Machine: The brewing method impacts the coffee's body and flavor profile. Choose based on your preference.

Glass Beaker: The star of our setup, replacing traditional measuring cups for precision and a visually engaging brewing process.

Putting It All Together

Start with high-quality, freshly roasted coffee beans for the best flavor. The freshness of your coffee beans plays a crucial role, so aim to use it as soon as possible after it's roasted, purchasing in small amounts ideally every one to two weeks​.

Grind your beans just before brewing to ensure maximum freshness. The grind size is critical and should be matched to your brewing method.

For example, a medium grind works well for drip coffee makers, while a coarser grind is ideal for French Press. A burr grinder is recommended for the most consistent grind size​. More importantly, only grind your coffee beans when you need it. Preground coffee beans will become stale, resulting in bland, dull, and weak-tasting coffee.

The recommended starting point for a balanced cup of coffee is 1:16, which translates to 1 gram of coffee for every 16 grams of water. To put this into perspective, if you're making a standard 8-ounce (about 237 ml) cup of coffee, you would need approximately 15 grams of coffee​​. This measurement ensures a balanced extraction, avoiding both under and over-extraction, which can lead to a bitter taste.

Use filtered or bottled water if your tap water isn’t the best. The water temperature is crucial to get the most flavour and aroma out of your grounded coffee beans. Using your beaker, heat up your water and measure its heat to be between 195°F to 205°F (approximately 91°C to 96°C) using a digital thermometer. This temperature range ensures that the delicate oils and flavors in the coffee grounds are extracted without scorching​.

The contact time between water and coffee should be about 2-4 minutes for French Press and approximately 5 minutes for drip brew. For espresso, the contact time is much shorter, around 20-30 seconds. The pour-over method allows for a controlled brewing process, letting you adjust the pour rate and ensure even saturation of the coffee grounds.

Coffee cools rapidly after brewing, and many drinkers add cream or milk, which further cools the coffee. The ideal serving temperature for coffee is a personal preference but is typically below 140°F (60°C) for most people.

Putting It All Together:

Start by using it to measure the exact amount of filtered water needed for your coffee. Heat the water in the beaker on a stovetop or with an electric kettle, then use a thermometer to ensure it reaches the correct temperature.

Next, pour your freshly ground coffee into your brewing device of choice. Slowly add the heated water from the beaker, ensuring even coverage over the grounds. If your brewing method allows, use a glass rod to stir the mixture gently, enhancing the extraction process.

The beaker can also be used to serve your brewed coffee. It's heat-resistant, looks visually stunning because it’s see-through, and c’mon! You just made the perfect coffee, and you won’t have to guess the next time you make it.

The Science Behind Coffee

I’m glad you stuck around! If you want to learn more about coffee and are fascinated how it all comes together, then keep reading. Because the science behind coffee is a fascinating exploration of chemistry, physics, and even a bit of biology. It's an interplay of various elements that transform simple beans and water into a complex, aromatic beverage enjoyed by millions. Let's delve into the science that makes your morning brew possible.

1. Chemical Composition of Coffee Beans

Coffee beans are rich in compounds that contribute to their flavor and aroma. These include caffeine, oils, acids, and sugars. During the roasting process, chemical reactions such as the Maillard reaction and caramelisation occur, altering the beans' chemical structure and developing the rich flavors and aromas characteristic of coffee.

2. Extraction Process

Extraction is the process of dissolving soluble flavors from coffee grounds into water. The main factors affecting extraction are grind size, water temperature, coffee-to-water ratio, and brewing time. The goal is to extract the right balance of flavors: too little extraction results in sour, underdeveloped coffee, while too much extraction leads to bitterness from over-extraction of undesirable compounds.

3. Grind Size and Surface Area

The grind size of coffee beans affects the extraction rate. Finer grinds have a larger surface area exposed to water, speeding up the extraction. However, too fine a grind can lead to over-extraction and bitterness. Conversely, a coarser grind slows extraction, which can result in a weak, under-extracted brew if not adjusted for with longer brewing time or hotter water.

4. Water Temperature

The optimal water temperature for brewing coffee is between 195°F and 205°F (91°C to 96°C). This range is critical because it's hot enough to extract the desirable compounds efficiently without extracting too many bitter compounds, which are more readily dissolved at higher temperatures.

5. Coffee-to-Water Ratio

The ratio of coffee to water is crucial in determining the strength and flavor balance of the coffee. The "Golden Ratio" is a general guideline, but adjustments may be necessary based on personal preference and the specific beans and brewing method used.

6. Brewing Time

The contact time between coffee and water also impacts extraction. Espresso, for example, uses a very short extraction time under high pressure, while French press coffee has a longer brewing time. Finding the right balance is key to achieving the desired flavor profile.

7. Acidity and Bitterness

Coffee's flavor profile includes acidity and bitterness, which are influenced by the bean's origin, the roast level, and the brewing process. Acidity brings brightness and sharpness to coffee, while bitterness can add depth, but too much can be unpleasant.

8. Soluble Yield

The goal of brewing coffee is to achieve a certain percentage of solubles yield, which is the amount of coffee solids dissolved in the water. The Specialty Coffee Association suggests a target range of 18% to 22% for optimal balance and flavor.