In the past two emails/blogs, I covered dialing-in espresso and cupping with the ever persistent argument that the goal in roasting should be sweetness. I received a great question related to my claim “Unlike the one-dimensional flavours of underdevelopment (sour) or over-roasting (bitter), sweetness is complex and the array of fruit, berry, citrus, and cocoa communicates a great deal about its unique origin and growing conditions”.
They asked, why do you consider sweet to be complex and sour to be one-dimensional
A perfect question that will – yet again – let me blather about my love of roasting 😏. There is a core dividing line between coffees that taste like their origin and coffees whose flavours solely reveal the impact of roasting. Roasting too hot or too dark will leave you with an identical progression of flavours: crackers, spices (especially nutmeg and clove), bittersweet chocolate, char, and finally acrid carbonation. Regardless of where the coffee is from, a roast that is dark enough will have the same universal and one-dimensional notes.
Conversely, a coffee that is undeveloped (typically caused by the inner bean or an inadequate first crack ratio) will have prevalent and ubiquitous taste notes: savory broth, grass or hay, and the sourness of under-ripe fruit, tomato acidity, and citrus pith. Hence under-developing or over-roasting will eliminate the particular flavours of origin and simply represent the roasting process.
Hence, sweetness is goal! When I profile a coffee for sweetness, it always tastes unique. An Ethiopian Adado can taste like apricots or peaches, a Guatemalan Huehuetenango might have milk chocolate, and a Sulawesian Tana Toraja can present key lime or juniper. The labour of amazing farms and cooperatives should be celebrated by using the roast process to emphasize the complexity of origin. There is a sad history (and still ongoing practice) of using dark roasts to eliminate unpleasant flavours that result from poor growing conditions (exploitative labour, poor environmental practices, inequitable trade, et al.), which as an industry we should no longer accept.
tl;dr: sour can be tasty but it should be balanced to sweetness (as it is in most ripe fruits) and should connect to the terroir, not stem from an error in roasting.