Quite simply, Roast Development (RD from here on) is one of the most important concepts in the coffee world. Its scope and nature determine the very flavours, colours and textures of every bean in every cup.

RD can be the lightest of fingerprints, crafted to deliver flavours which reflect the unique terroir and processing method of an origin. Think of when you’ve experienced zesty citrus, delicate florals or rich jammy berries. In general, this style is synonymous with specialty coffee and remains the holy grail for its roasters.

Conversely, RD can also be more of a blunt object, ensuring those more traditional ‘roasty’ notes regardless of country of origin, punch through your 12-ounce latte and into your very soul.

Then, of course, there is the awful half-world where you get it all wrong and don’t achieve enough development, leaving the coffee tasting sour or wheaty, and you realise you’re an abject failure and even your cat hates you more than usual.

So as a roaster, how do you decide which level of RD is best and, at the same time, avoid the shame and ignominy of underdevelopment hell?

Historically (and quite sensibly), the coffee industry has long used colour as a main signifier of degree of RD. Prior to data collection, this was the most obvious tool available to a roaster during the roasting process. You simply let the roast go on until the beans reached the desired level of ‘brownness’. (It was a highly technical time).

  • Light brown roasts were ‘underdeveloped’.
  • Medium brown roasts were ‘developed’.
  • Dark brown roasts were ‘over developed’.


But then, it wasn’t really. Because what was medium brown for some people was dark brown for others and vice versa. Because these terms are completely subjective, they were only relative to a roaster’s personal concept of what was ‘brown’. So a dark roast could taste underdeveloped and sour anyway, because the colour inside the bean needed to be measured as well. Much like a Sunday roast, getting the heat/time ratio correct is absolutely crucial for RD, otherwise the outside can be ‘well done’ but the inside still completely raw.

As the industry evolved and strove to apply more scientific rigour to its processes, it became clear that ‘how brown?’ wasn’t a very scientific way of qualifying and quantifying the degree of complicated chemical reactions which had occurred via the variable application of heat to a complex organic structure.

To this day, there are no universally-agreed colour spectrometer numbers to define what is ‘light’, ‘medium’ or ‘dark’, because in the end, RD isn’t actually about colour at all. It’s really about flavour. Colour thus only gains significance when referenced against flavour. And luckily, flavour isn’t subjective at all, is it? (#sarcasm).

But, as we’re in specialty coffee, we can provide some (very general) guidelines around flavour expectations. So, let’s rejig that original schematic to reflect our new, flavour-based concept of RD.

Does your coffee taste -:

  • Sour, grassy or wheaty? ‘Underdeveloped’
  • Balanced, rounded and well structured? ‘Developed’
  • Bitter, toasty, ‘strong’? ‘Over developed’

Of course, for many roasting companies (and coffee lovers), those last descriptors are actually positive. As such I would argue that the term ‘over developed’ is misleading, as it implies an error occurred in the roasting process when, in fact, it could be a legitimate, targeted sensory profile.

So, we need to rework these definitions almost immediately. Because it’s not really about being ‘over’ or ‘under’ developed – it’s about the style of development.

Or, in other words, achieving the best RD is ensuring a targeted level of structural change in the coffee bean is delivered by a targeted roast profile which is deliberately crafted to deliver targeted flavour outcomes.

Or we could simply say that RD is all about how well the roast achieves its purpose.

Purpose is the most important reference point against which we judge our roasting success or failure. It provides the context which allows us to determine how well we’ve done our job. On the cupping table, one coffee can have a bright acid and be judged as spectacular. Another can have a bright acid but be slammed.


You guessed it – purpose. After all, you can’t judge a sprinter by how fast they run a marathon, can you? Well you can, but it makes you look like a bit of a judgy asshat.

So, the first question a roaster needs to ask when looking to craft a roast profile is ‘Why did our green bean buyer source this particular origin?’ Is it meant to be fruity? Or deliver light and zesty citrus notes? Or be heavy and chocolatey? Further, is it mainly going to be drunk as a long black, with milk or as filter? Is it to play the unassuming role of ‘delivering body’ in a blend, or stand alone as a spectacular single? Is it Diana Ross or The Supremes?

Therefore, we can safely assert there is no universal ‘best’ roast development. Rather, your success as a roaster rests entirely upon how well your carefully crafted roast profile delivers on your purpose. Now what is absolutely crucial to remember here is that different roasting companies can have different ideas of ‘purpose’ even for the same origin. What one roaster considers a ‘blend’ coffee designed for the latte crowd can instead be a standout long black single for another. Or an origin which delivers sprightly, tart apricot notes can also be curated to deliver richer dark fruits with a spine of velvety milk chocolate. It all comes down to what you want from a coffee, and how successfully you manipulate your roast development to achieve it.

So, where do we begin? That will be the focus of our next article where we investigate just how a roaster can go about crafting a roast profile, identifying all the tools at our disposal during the roasting process and considering the various types of decisions to be made. We’ll also identify the many challenges and variables we face along the way and look at their impact on the cup. Finally, we’ll explore the surprising wider implications (and benefits) of achieving consistently excellent Roast Development – not only for the consumer, but also right back to where our journey began in a country far, far away…

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