How to Brew (and Drink) the Perfect Cup of Coffee, According to Science
Let’s be real: For many of us, that perfect cup of coffee is a non-negotiable part of our morning routine. If it goes awry, the whole day can just feel…off. In theory, the easiest way to avoid such a catastrophe is to buy your morning joe from a coffee shop that brews it just how you like it. That said, it’s also perfectly understandable if you’d rather brew it at home — whether to save money (just remember: buying a daily coffee won’t singlehandedly bankrupt you or keep you from getting rich); to spare the environment of wasteful single-use cups; or because you prefer the convenience, comfort, and safety (hello, pandemic) of home-brewed coffee.
If that’s the case, it’s worth spending some time learning how to brew the perfect cup of coffee to make sure that java is actually accomplishing what you need it to. Of course, there are endless reasons someone might want coffee — and endless types of coffee drinks they might reach for — so let’s focus in on a classic: drip coffee that you drink to wake up and get a much-needed boost of energy. Luckily, decades of scientific research have helped us figure out how to brew, and drink, that perfect cup of joe. While the final product is ultimately up to your individual taste, these tips will get you started on brewing coffee that’s as good as your favorite coffee shop’s — and getting the most out of it when you do:
1. Drink coffee during the right windows of time.
You know that saying, “But first, coffee,” that dominates Etsy craft shops? That might not be the best mantra if you want to get the most out of your morning brew. Your body naturally produces a hormone called cortisol that, among other effects, can cause bursts of energy when it’s at a high level. This has to do with cortisol’s role in your body’s fight or flight response in the presence of stress or fear. So, what does it have to do with your coffee habit?
If you introduce caffeine into your system when the cortisol level is high, you’re not experiencing the caffeine at its peak efficiency. In fact, you might just be building up your tolerance, which means you would need more and more caffeine to achieve the same buzz.
Cortisol levels rise and fall throughout the day, in relation to sunlight and your body’s sleep schedule. If you typically sleep at night and are awake during the day, your cortisol levels likely peak first thing in the morning — so it's actually a good idea to hold off drinking your coffee for an hour to 90 minutes after you wake up. (I know, I know: easier said than done.) If you’re a two-cup-a-day kind of person, try to time your second coffee to align with your next cortisol dip. The levels usually rise again around noon, so wait until about 1:30 p.m. for your pick-me-up.
2. Store the beans properly.
Not all coffee bean storage is created equal; if you want your brew to live up to its full potential, you need to make sure your beans are stored accordingly. "Cool" and "airtight" are the operative words here. As the National Coffee Association (NCA) points out, the packaging your coffee comes in probably isn’t sufficient — and neither is that aesthetically pleasing glass jar you had your eye on. Instead, transfer your beans to an opaque container that keeps air out (ideally one designed for storing coffee beans). You’ll also need to keep the beans out of moisture, heat, and light — so consider storing them in a cabinet away from the oven or other heat sources. Some people even suggest freezing the beans and thawing them before use if you want to buy larger quantities at once, but your better bet is to go with smaller batches for optimal freshness.
While you’re taking steps to ensure freshness for your perfect cup of coffee, make a point to buy whole beans rather than ground coffee. As HuffPost reports, coffee oxidizes — and becomes more stale and less flavorful — when exposed to air, and that exposure is inevitable when you grind coffee beans. So, you’ll get your best cup of coffee if you buy whole beans, store them properly, and grind them only when you’re ready to brew.
3. Decide how much caffeine you want.
Although caffeine is a part of our daily diet — a 2014 study published in journal Food and Chemical Toxicology found that 85% of people in the U.S. consume at least one caffeinated beverage each day — it’s up to you to determine how much of America’s favorite fuel you’re comfortable with. According to the Mayo Clinic, up to 400 milligrams of caffeine each day (roughly four cups of brewed coffee) is safe for most healthy adults.
You may need to do a bit of trial and error to figure out what’s right for you; and once you do, you can choose a bean and roast that will work for your perfect cup of coffee. It’s not just about flavor; different beans and roasts contain different levels of caffeine. When it comes to the two most common types of coffee you’ll encounter, the arabica bean is more popular and better-tasting, but the robusta bean contains twice as much caffeine. Dark roasts tend to contain less caffeine than light roasts, because it gets burned off during the roasting process.
4. Perfect your grinding method.
As previously noted, grinding coffee beans right before brewing can make a world of difference in the flavor and potency of the final result. America's Test Kitchen recommends using a burr grinder; but if you're using a blade grinder, the important thing is to grind in short bursts for an even result. To make that perfect cup of drip coffee, aim for a medium grind (as this infographic from I Love Coffee notes, it should be the consistency of Kosher salt). The best burr coffee grinders have multiple settings depending on how coarse or fine you want your beans, and many even specifically tell you which setting to use based on your brewing method.
5. Take note of the ideal brewing temperature and time.
The perfect cup of coffee is an art, sure, but it’s also a science — especially when it comes to factors like brewing temperature and time. According to the NCA, the best water temperature for your brewer is between 195-205 degrees Fahrenheit; if you’re brewing manually (rather than with an automatic coffee pot that heats the water for you), wait until the water comes to a full boil, turn off the heat, and wait about one minute before pouring it onto the coffee grounds.
As for ideal brewing time — which is the amount of time the water is actually in contact with the coffee — the NCA recommends five minutes for drip coffee. If you go the French press route, two-to-four minutes is best; and if you’re making espresso, the contact time should only be 20-30 seconds.
6. Be mindful of "the golden ratio."
Back in the '50s, MIT chemistry professor E. E. Lockhart conducted an extensive survey to determine the ideal ratio of coffee beans to water. As The Atlanticreported, the formula he came up with — now known as the “Golden Ratio” — has withstood the test of time: 17.42 units of water to 1 unit of coffee. You can change the unit to whatever you want: grams, ounces, pounds, etc. Just keep the ratio, and you should be fine. There's a reason it’s so popular. Perfect cup of coffee: achieved.