For many of us, the day doesn’t start until we’ve had our first cup of coffee, whether it’s an espresso, a latte, a cappuccino, or a large mug of instant coffee. The first rush of caffeine is necessary to get us going, but the variety of coffee and roasting options can be overwhelming. Limerick Institute of Technology’s Agnes Bouchier Hayes appeared on RTÉ Radio 1’s Today With Claire Byrne show to discuss what’s on offer and how to make your favourite coffee. (Excerpts from the conversation have been gently edited for length and clarity; the entire conversation can be heard above.)
Bouchier-Hayes started with a primer on coffee beans, which are the source of the caffeine in the first place. “There are four primary varieties, although the most common are two. The Arabica bean is the first, and the Robusta bean is the second. The Liberica and the Excelsa are the other two beans. Now, the Liberica has been wiped out by a disease known as coffee rust, and it has been declared extinct. However, it is beginning to resurface, and the Excelsa is mostly produced in Southeast Asia.
“The Bean Belt is where we obtain the majority of our coffee from. That covers all of the world’s sub-tropical and equatorial regions, including South America, Africa, and Asia, so there’s a wide range of terroir. It’s the same with wine: you only have so many grapes. Beans, too, have a set number of beans, but the soil in which they are produced, as well as the environment in which they are cultivated, all have an affect on the flavour of the bean. After that, of course, comes the roasting.”
The maths behind a great cup of coffee, courtesy of RTÉ Brainstorm.
So, what happens when you roast something? “You’ll roast it in stages, starting with light and progressing to dark. They’re more acidic in the lighter roasts and can be bitter in the darker roasts. So it’s time to fire up the roaster. This is when the artistry comes into play. Roasters would each have their own unique method of roasting, but they would all go through the same stages. It all depends on how it’s roasted and how rich it becomes.
“The darker the roast becomes, the more oils are produced, and the flavour might turn bitter. You don’t want it to burn, but that’s where the coffee’s flavour and development of scents and flavours come from.”