If you're bewildered by the array of coffee --- ranging from $1 per pound to $12 per pound --- here's one simple trick that will help you determine if the coffee you're purchasing is high quality roasted coffee.
Just put one tablespoonful of coffee on top of a glass of ice water. If your coffee stays on top of the water and does not leach into the water after a few minutes, it's been roasted properly. If it leaches, then it's either over-roasted or under-roasted. Keep reading to find out why this trick works.
How High-Quality Coffee Tastes
High-quality coffee should balance acidity, sweetness, and bitterness in one sip, with a smooth flavor, and no off-notes.
That's a complex way to say that that good quality coffee should taste good. It shouldn't taste burnt, charred, or raw. It should have complex and nuanced flavors. It shouldn't taste bland. It shouldn't taste overly sweet, bitter, or acidic. It should feel smooth on the tongue. It might have fruity, floral, or earthy flavors. It should leave you wanting another sip, without sugar or milk.
What Makes a Good Roast
There are three parts to making a high-quality cup of coffee: good coffee beans, good roasting, and a good brewing system. Of these three parts, roasting might be the most important, followed closely by the bean production.
The roasting process produces the characteristic flavor of coffee, by causing the green coffee beans to change and expand in flavor, smell, density, and color, using several chemical reactions. Lighter roasts will allow the bean to exhibit more of its original flavor, meaning the flavor created in the bean by its variety, soil, altitude, and weather conditions. At darker roasts, the flavor of the roast itself becomes so dominant that it is difficult to distinguish the origin of the bean.
The Problem With Under-Roasted or Over-Roasted Coffee
The Maillard reaction is a chemical reaction between amino acids and natural sugars in reducing foods that results in the browning of food to result in stronger tastes.
The Maillard reaction intensifies at around 200 degrees Celsius (392 degrees Fahrenheit). When a coffee bean reaches this temperature, it will make a popping sound, known as the "first crack," marking the beginning of light roasts.
Under-roasted beans --- or beans that are not heated to the first crack --- will not caramelize. This means that the natural fructose in the coffee bean will be at a very high level because un-caramelized fructose is actually sweeter than caramelized fructose.
As the coffee bean is roasted longer and at higher temperatures, the amino acids and natural sugars in the coffee bean break down and continue caramelizing. However, after around 250 degrees Celsius (482 degrees Fahrenheit), the beans char and the amino acids break down again, releasing more fructose.
In other words, under-roasted and over-roasted coffee will have excess sugars in them and will not be properly caramelized.
Does Your Ground Coffee Leach Into Ice Water?
Emmanuel, the guide at Finca Rosa Blanca sustainable coffee plantation, explained that the best way to tell if your coffee has been roasted well is to place a tablespoonful of ground coffee on top of a glass of ice water. If your coffee leaches into the ice water within a few minutes, it has been either under or over-roasted, because the sugars are leaching out of the coffee into the water. If it doesn't leach (even after a half hour), you've got properly roasted coffee.