If you had enjoyed our roast of the Mexico Siltepec Organic coffee, we’d like to share with you what went on behind the scenes to get the coffees to taste just how we’d like it!
A little backstory – we’ve been roasting coffees for our small coffee bar since end 2018, out of the first co-roasting space in Singapore, Compound Coffee. Before we decided to embark on this journey, we were serving coffees roasted by Compound Coffee with a little twist; we worked very closely with their Head Roaster, Kenneth on exactly the kind of coffees we wanted to serve. I had previous experiences on different roasting machines such as Diedrichs, Probats, Bella etc but I had not had the opportunity to roast coffees on a Giesen roasting machine before. After several sessions with Kenneth on the W6A, we decided to start exploring our own roast profiles for our coffee bar. That was the beginning of a rewarding, yet frustrating journey of learning, re-learning & discovering – and boy, am I glad we got to share these experiences with the good people at Compound Coffee.
Roasting coffee is easy. Roasting coffees well is… slightly more challenging. Roasting coffees excellently & consistently is by far one of the most challenging things ever. One thing I’ve learnt & will always share with new, aspiring or old roasters alike; never be afraid to ask for help. I’ve been very lucky in my short roasting experience to have learnt, watched & practiced with whom I regard as the top in this field. In the couple of years we’ve been roasting at Compound Coffee, Kenneth & I have exchanged numerous views & multiple differing opinions on how to roast coffee better. This coffee is a culmination of our knowledge, experience & preference.
One important thing Kenneth & I agree on is the definition of roast development. In our roasts, we seek to fully develop the coffee & this means sweetness that’s characterised by ripe fruit notes. We acknowledge that sweetness can also come from the degree of caramelisation, which is where our difference in preferences lie. Some of the differences in our roast approaches are:
- Batch sizes.
We typically use a 4kg batch size for the W6A, as we believe it provides the best mass/volume for a more even roast. I actually prefer 3.5kg for better flavour development, but 4kg makes more sense economically.
- Drum Speed.
Due to the batch size, we opt for a higher drum speed of 55hz (around 85-88RPM) to allow for a more convective roast.
- Time – Temperature – Energy Targets.
Our roast strategy is based on achieving temperature targets at certain times with appropriate energy (Bean Temperature Rate of Rise). This is to ensure we do not input too much heat energy (under developed flavours with toasty notes) or too little (flat or baked flavours).
- Development Time after First Crack
With the appropriate energy level based on the coffee’s density, size & processing method, we decide on a development time & end temperature to ensure the coffee showcases ripe fruit notes with minimum caramelisation.
The above graph shows our roast profile of the Mexico Siltepec Organic. This coffee had a low-medium density (810g/ml) and medium moisture (10.3%). We immediately formulated a roast profile based on this data which looked something like this:
a) coffee requires a slower roast due to its density to ensure sufficient development. This gave us a ballpark of when we should hit first crack, which was 9:15 to 9:45. Its density also gave us an idea of the energy level we should have at first crack (Rate of rise of 9.0-8.0 degC/min)
b) to achieve said first crack timing, we picked the initial gas setting for the charge temperature, keeping in mind the coffee’s moisture level as well hardness.
After witnessing the peak Rate of Rise level, we steadily decreased the burner capacity to ensure a slowly declining Rate of Rise, ensuring sufficient inner bean development. It was also important that we met each Time – Temperature target at the right energy level.
This coffee was dropped 1:25 into first crack after we determined the energy level to have declined considerably that it would have developed enough sweetness without incurring too much caramelisation. This roast measured 68 points (outer Surface colour – High) and 87 (inner ground colour – Cinnamon). More importantly, how did it taste?
It became obvious as soon as the crust started forming on the cupping that this coffee would showcase comforting flavours like milk chocolates & baked nuts. What was a nice surprise was the sweet yet juicy acidity one would liken to baked apples. The coffee had a nice depth & structure as well as a round mouthfeel that finished long & sweet. Overall, it was a great showcase of clean, ripe flavours – a hallmark of well produced & well processed Latin American coffees.
We thoroughly enjoyed roasting this coffee & exchanging roasting tips with Compound Coffee. This collaboration was intended as a “Giving Back” initiative to the producers of this co-operative. Read more about it here. If you would like to enjoy this coffee from the comforts of your own home, you can purchase this coffee from us here.