Roasting Coffee Beans at Home
by T House, Australia.
Like all true coffee lovers, I’m always looking for that “perfect” coffee. Many weekend trips to Lygon Street in Carlton, Melbourne, were rewarded by truly great coffee. But where can I get that perfect cup?
The Search for the Perfect Brew
Overseas trips to the United States, Spain, Italy and the Caribbean gave me the chance to sample a wide variety of coffees, some truly terrible, some average and a few better than average but none rivalling that consumed in our favorite spot in Lygon Street.
In anticipation of a very long flight to Cuba in 2015, I downloaded many TED talks to view inflight. One was to change my coffee preparing and drinking habits forever. If you are interested, I commend the TED talk “What you didn’t know about coffee” by Asher Yaron. In his talk, Yaron’s bottom line is that roasted coffee is a ‘living’ food which dies within a week, despite vacuum packaging, refrigeration or other storage methods and therefore, unless you have a guaranteed supply of truly freshly roasted coffee beans, you should roast your own green beans. It made sense that stale beans could limit the “potency” and ruin the flavor of the coffee, but I assumed vacuum sealed bags of pre-roasted coffee beans would not be stale. Little did I realize at the time that Yaron’s talk was to start me on my coffee roasting journey in the search of a perfect brew.
My First Roast
Once back home and guided by Yaron, my first attempt at roasting used nothing more than a simple air popcorn maker. After a little experimentation, I was able to roast small quantities of super fresh coffee beans. Further research indicated that I needed to modify my DIY roaster to add a means of temperature stability and a means of adjusting the flow of hot air over the beans during the roasting process. A picture of my final DIY roaster is shown in Figure 1. This allowed me to produce good consistent results but only in small quantities.
Encouraged by my coffee-loving wife, around 5 years ago I threw caution and about $350 (AUD) to the wind and purchased a small professional domestic coffee roaster. Ever since I have been experimenting on blends of beans and the degree of roasting. Our current favorite is a blend of Guatemalan, Nicaraguan and Honduran beans roasted just less than a full-strength roast. The beans are sourced from a local coffee store with the added benefit that green beans are supplied at half the price of roasted ones. Figure 2 shows our coffee roaster.
How We Roast Our Beans
The roasting process is relatively simple and, provided you concentrate fully, reasonably safe. The roasting process involves placing green beans into a drum which is placed in the pre-heated roaster. The drum is very close to a heating element and rotated to ensure the beans are evenly heated. Depending on the amount of beans, the roasting time is pre-programmed, but a little manual override is possible. Roasting involves bringing the beans to what is call ‘first crack’, where the beans split slightly. For a 200 gm roast, first crack occurs about 7 minutes from the start of the roast in my machine. From there, the oils in the beans are slowly released while chemical processes occur within the bean to caramelize some of the sugars. After a further 3 minutes the beans then go through a process called ‘second crack’. Once second crack has occurred the beans become progressively darker and oilier as the oils are released. At this point, care must be taken to make sure the oils do not ignite. For us, 30 seconds after second crack produces an acceptable richness without bitterness. After this time, the drum is removed and the beans cooled quickly by tossing them between a sieve and a metal bowl, preferably in the wind, to remove some of the chaff. They are then blended and stored in an airtight container for about 24 hours and always consumed within a week.
Interestingly, but a little disappointingly, the roasting process does not produce that gorgeous smell throughout the house that one gets with the brewing process. The smell during the roasting process is a quite ‘grassy’. That said, after 24 hours the beans smell beautiful.
So, after all this is our coffee ‘perfect’? No, but the search for that perfect coffee is but another of life’s continuing quests.
T House, Australia