Quest for Coffee (2) | Roast

So what is the deal with the different roasts? Do they really make a difference?

The short answer is…yes.

When a coffee bean undergoes roasting, some very interesting processes take place. Don’t panic. While there are some complicated scientific reactions going on, they will be explained very simply here on Quest for Coffee.

It’ll be fun.

So to break it down, 3 main things usually change during roasting—colour, flavour and fragrance. 

Colour

Different roast levels alter the colour of the beans, which consequently affects the colour of your brewed coffee.

• Light Roast (Cinnamon Roast or New England Roast): Roasted for a shorter period, the process usually stops before the first crack is fully developed.
  
  First crack essentially refers to the moment the bean expands from the heat and starts to crack, giving that familiar curve in pictures. Beans maintain their light brown colour, giving the brewed cup of a joe a subtle, pale amber hue.
  
• Medium Roast (City Roast): Needless to say, a medium roast is when the bean is roasted for some time longer than a light roast, or more specifically, before the second crack. This usually occurs at around 230 degrees Celsius.
  
  Second crack is the technical term for when the coffee bean undergoes a breakdown of cellulose and release oils. They continue to darken and often become oily and shiny.
  
  Now your brewed coffee is a deep, rich brown with a fuller colour. Think of your average Americano at the coffee shop.
  
• Dark Roast (Espresso, French Roast): Unrivaled in the dark shades of brown, these beans are roasted until they are nearly black and could have an oily, glossy surface due to neutral oils forced out of the beans.
  
  Most commonly used for espresso shots, the beans give a very dark final brew, with a possible hint of reddish hue. (Try it for yourself by pulling an espresso shot with dark-roasted beans versus light-roasted beans and notice the subtle colour differences)
  

A Quick Break – The Maillard Reaction 

As our tiny green, raw and harvested beans undergo roasting, they inevitably also undergo the Maillard reaction.

You might have stumbled upon this fancy term in a cooking tutorial (as explained by Masterclass), where the browning of meat on a grill is described with this reaction. When meat is grilled, the heat causes the proteins and sugars to react, producing a brown, crispy crust with rich, savoury flavours.

The browning is a direct result of the Maillard reaction. This same chemical reaction occurs during roasting, where the amino acids and sugars give the coffee its complex flavours and colour.

Rule of thumb? The darker the roast, the more pronounced this reaction becomes, the more “caramelised” our beans, the more complex the flavour.

Flavour

Now that we know how heat causes the Maillard reaction, here’s its massive role in shaping the flavour profile of coffee. 

• Light Roast: In a light roast, the original flavours of the bean, called origin characteristics, are more noticeable.
  
  You’ll taste fruity, floral, or even herbal notes. How in the wondrous wizarding world could this happen?
  
  Well…it’s due to terroir, a fancy name for “environmental factors”. Some of the natural flavours and characteristics of the environment where the bean was grown get carried forward through processing and roasting.
  
  Some of that original “genetic” flavour stays with the light roasted bean.
  
  Here comes the kicker: acidity. Often thought of as sourness, acidity is ironically not the same as sourness, but rather a lively, sparkling taste that some describe as fruity or wine-like.
  
  Try to taste the acidity (like in an orange) in your next coffee from light-roasted beans rather than the sourness (like a lemon), you might have a new discovery.
  

• Medium Roast: Further roasting causes the natural acids to decrease and the sugars in the beans to caramelise.
  
  This balances the acidity by bringing out chocolatey, nutty, or caramel-like flavours. It’s really just more “sweet” flavours, like sugar to lemonade to neutralise the sharpness.
  
  Coffee brewed from here may have a slightly earthy undertone but a smooth, balanced cup.

Remember our Maillard reaction? Well, this is the time. After the first crack, the browning effect becomes more pronounced as the Maillard reaction intensifies and out comes a rich, sweet flavour, cutting through the perceived acidity. 

But what if you like your coffee strong and bold? Fear not, introducing…the dark roast.

• Dark Roast: Dark roasts are known for their bold, smoky, or even burnt flavours.
  
  The original flavours of the beans take a backseat to the flavours developed during roasting, such as chocolate, toffee, or even bitter burnt notes.
  
  A French roast (another interchangeable name for dark roast) coffee might have hints of dark chocolate, molasses, and a tad of smokiness. It is often described as more full-bodied.
  

Wake Up And Smell The roses Coffee

The fragrance of coffee is one of its most delightful characteristics, and it’s profoundly affected by the roast.

• Light Roast: Freshly brewed, light roasts often have a more delicate fragrance, usually citrusy or fruity.
  
  A freshly ground light-roast Kenyan coffee will release a vibrant, floral aroma that might remind you of bergamot or green tea.
  
  If you ever wondered how such aromas waft through the air, it is all thanks to compounds called “volatiles”. Volatiles are aromatic compounds in coffee released during grinding and brewing, partly due to the heat.
  
  Light roasts tend to have more volatile compounds preserved, contributing to their fragrant, fruity notes. 

• Medium Roast: The fragrance becomes a little more rounded and caramelized. You might catch a whiff of nuts, chocolate, and brown sugar. (Again, the Maillard reaction is at work.)
  

• Dark Roast: Dark roasted beans release a rich, often smoky fragrance, which is a mix of charred sugar and heavy caramelisation. Think barbeque but without meat. Some beans might give a heavy, almost leathery fragrance, with notes of tobacco and dark chocolate accompanied by a strong, smoky scent.

Conclusion

Just as the type of beans play a role in the overall look, taste and smell of your coffee, so does the roast.

You could think of roast as the magnifier of flavour and the prelude to the brew, without which coffee would not exist.

Ever wonder what beans would do under pressure? The adventure continues…

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Take the next step in the Quest for Coffee to explore beans under pressure.

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