Credit: © James Kerr

Though it only has two ingredients, brewed coffee has even more known flavor compounds than wine. How do experienced coffee tasters figure out what's going on in a cup? They practice.

The most basic palate-sharpening exercise involves getting a grip on the five key flavors: Sweet, sour, bitter, salty and savory (a.k.a. umami). Though it might seem remedial, focusing on these properties is an eye-opening way to hone your sensory skills. Once you can reliably identify these flavors on their own, you'll be on your way to picking them out of the crowd of aromatic and flavor compounds in coffee.

You'll need:

Six 5 ounce glasses of water
Granulated sugar
A lemon
White vinegar
Flavor Boost or MSG powder
Table salt

Prepare the six solutions below, then taste through them as you read how their flavors relate to coffee. Then, have a friend serve them to you blind. You might be surprised at how tricky it is to ID some of these flavors when you're not sure what to expect.



1 teaspoon of granulated sugar dissolved in 5 ounces of water

Humans are wired for sweetness. Since sugars are our main source of energy, our taste buds are designed to seek them out and our brains tingle when we find them. There's a reason we're attracted to the flavor of ripe fruit.

Since coffee beans are the seed of a fruit, we should expect—nay, demand!—that coffee tastes sweet when brewed. And it does—when coffee cherries are picked at their plumpest, and their beans are brewed properly. Since improper harvesting and bad brewing is so common, sweetness is the fire rainbow of coffee flavors—unexpected, stunning and dependent on perfect conditions to occur.


Solution No. 1: juice of 1/2 lemon in 5 ounces of water
Solution No. 2: 1 teaspoon of white vinegar in 5 ounces of water

These solutions represent the two basic types of sourness, which recall the puckery qualities of citrus and vinegar. In small doses, sourness can add a pleasant depth to coffee; when it overwhelms sweetness, sour can be a drying, painful flavor that erases complexity.

Excessive sourness in coffee is often caused by one of three things: There's unripe coffee cherries (just as an underripe banana has an unpleasant tartness and dryness, underripe coffee fruit can produce similar flavors). Poor processing, and in particular something called overfermentation, can cause sourness. And there's a specific brewing mistake that can make coffee taste sour, which we'll address in a future post.


1/2 aspirin dissolved in 5 ounces of water

Bitterness tends to be misunderstood and underappreciated. As one taste among many, it can add incredible depth of character, complexity and balance to almost anything. Especially combined with sweetness, it can profoundly elevate a food or drink experience.

Coffee will always have a touch of bitterness, since it's the flavor of the beloved alkaloid caffeine. In fact, excessively bitter flavors can be a sign that too much caffeine and other compounds have been extracted during brewing.


1 teaspoon of Flavor Boost or MSG powder dissolved in 5 ounces of water

The difficult-to-describe "fifth flavor," also known as umami, is caused by glutamic acid. This is the compound that creates the elusive mouthwatering taste present in meat, beans, mushrooms and seaweeds.

In coffee, savoriness often comes from air- or waterborne yeasts that aid the fermentation process that coffee goes through during processing. Coffee producers around the world approach fermentation differently, and local yeasts can amp up or tone down a coffee's level of savory flavors.


1 teaspoon of table salt dissolved in 5 ounces of water

Salt isn't hard to spot, and in coffee it usually means something is wrong. Except in very rare cases of quirky processing, salty coffee usually points to salt in the water used to brew, either from the tap or the kettle. It can also mean that your filters have been improperly stored, or that the coffee has absorbed flavors from elsewhere because of poor handling. Some people actually prefer to add salt to their coffee, but that's neither here nor there (and this writer doesn't recommend it).