It’s very seldom a roaster gets to taste the same coffee roasted on the same (to all intense and purposes) machine by different roasters with different intentions.
At last weekends Bristol Coffee Festival we took our latest washed Ethiopian coffee Boreta Daye Bensa. We weren’t the only ones and this is clearly a popular coffee amongst some of the best roasters around right now (which means we’re in good company), and all of whom I have great respect for.
One of these also at the event was Ben from Harmony Coffee. Ben slot-roasts (he doesn’t own a roastery.. yet), on a Loring S-15 and was brewing it on his stand at BCF. Ben’s known for clean bright filter coffees and I was keen to taste his take on this coffee. It was as expected.. light, fresh, clean and delicious. It made me question our own approach to this coffee since ours is a little ‘heavier’, more sweetness and body and ripe stone-fruits rather than ‘just’ ripe. I asked Ben about his drop temp (the temperature at which the coffee drops out of the roaster into the cooling tray and a good indication of the intensity of heat energy is being applied to the beans at the final stages of roasting). Ben’s was at 205.7, our is closer to 208.5, nearly 3degC more. I can compare these since we’re both using machines from the same manufacturer which means the temperature probes are the same (same speed and accuracy) and probe placement inside the roasting space is the same.
Our roasting ‘style’ is known as omni-roasting which means it’s in the middle of what you’d consider ideal for filter or ideal for espresso. The main difference between ‘filter’ and ‘espresso’ profiles is the added time in the roaster for Maillard (and other) reactions to take place and CO2 pressure to build up in the bean and shatter the cellular structure making the coffee more soluble (and therefore more easily extracted). The lighter you go the less cellular breakdown and the less soluble meaning that only highly soluble compounds are available during normal brewing conditions.
I didn’t ask Ben (perhaps I should), about the colour readings for his coffee. We have a few scales typically used in the coffee world but the AGTRON Gourmet scale is probably the standard for colour. We have an instrument that enables us measure the colour of the outside as whole bean and also the ground (which is obviously an average of the outside and inside all mixed together). With a light roasted coffee the outside would be light and the inside even lighter. I would assume that ours would show darker on the outside and also darker inside and a lesser difference (delta) between the two.
One major difference between the two styles is the green or grassy notes that very light filter roasts have when the coffee is super fresh (close to roast date). The lack of cellular breakdown and absence of CO2 pressure means that CO2 will leave the matrix very slowly. Light roasted fresh coffee exhibit a sharp harsh astringency because of the high amount of carbonic acid that is created during brewing along with the lack of solubility of various flavour compounds. Some roasters recommend a minimum 3 weeks rest time for this style of coffee since before that they’ll exhibit these astringent notes. Ben’s coffee had none of those astringent notes and I suspect (again I should have asked) how long after roast it was.
By developing the coffee further (more time, more temp), we are negating these astringent notes and roasting coffee that needs much less resting time to brew. There’s always a CO2 degassing component with freshly roasted coffee since it’s one of the major by-products of the roasting process. With our coffees we typically recommend a week after roast date when the coffee is at it’s best for filter brewing, a little longer for espresso. There’s a practicality side to consider too. Roasting super light means that the rest time is much longer and therefore you’re asking a customer to order, then wait.. for weeks before the coffee is ‘good’ to brew. Alternatively you roast ahead.. anticipating that in a few weeks time you’ll have sufficient orders to enable you to use the ‘rested’ coffee.
Just like everything else.. roasting is a compromise. Roasting super light, suits certain coffees only. Those delicate floral and super bright coffees we’ve been treated to from Panama, Ecuador and Colombia in recent years, Geisha’s, Sidra’s, Typica Mejorado etc. Those varieties, origins and processes suit light roasting to showcase the inherent properties. A high yielding Castillo from Colombia or a Catuai grown at 1000m in Brazil does not, and the aim of a roaster is to enhance the sweetness and body that these coffees can offer.
It’s not a one-size fits all world, and roasting is the same. Our roast style is ‘safe’ in that we develop the coffees sufficiently to avoid astringent dryness and the need to rest our coffees for 3+ weeks, but not too developed so as to overpower the positive nuanced characteristics that are inherent in the coffee. We feel they suit both filter and espresso brewing, but purists may argue that our style is too heavy for filter and too light for espresso. Everyone has an opinion and ultimately it’s a customers choice as to which roaster’s style they prefer.