Roast Approach: Roast Levels and Roast Colors

Within the roasting world, there are countless ways to describe a roast.  For those who roast, the terms "cinnamon", "city", "full city", "vienna" and "french" are often thrown around.  For the common coffee drinker, terms like "light roast" and "medium roast" have permeated the everyday vernacular.  Even within segments of the coffee industry, many companies have their own classification system for their coffee roasts.  All together, it makes a very confusing landscape for a person who is learning coffee roasting or is trying to communicate to a consumer what they can expect in the bag.  Recently, I attended a Re:Co SCA symposium dedicated to the discussion of "coffee color".  The biggest take away from three days of in-depth discussion at the highest level with lifelong coffee experts was that there is absolutely no consensus regarding coffee color, nor are we anywhere near one.  There was no agreement on any kind of standardization of roast color, nor was there even a consensus on whether such a standard should even exist.  

My opinion on the matter is that the way you describe your coffee should be useful to you. As a roaster who sells coffee, you should use language that fits in with the way your clientele are describing coffee.  If you are engaging in discussion or educational adventures with other roasters, the way you talk about your coffee may be very different.  It's always important to remember that your customers and your peers speak about coffee in two different dialects.  

With so little consensus on roast levels, I like to think about who we are trying to connect with and what the end goal of that communication is.  Below we walk through two different ways of discussing roast levels, one aimed at connecting meaningfully with our customers and one aimed at connecting with our peers.  

Connecting with the coffee drinker

If the modern roaster is looking to connect with a consumer, they are left with the task of trying to figure out which dialect of coffee the person is speaking.  With all of this confusion and opportunity for miscommunication, I find it most helpful to use the most basic descriptors as a sort of "rosetta stone" for understanding what the consumer is looking for.  A classic medium roast coffee can be described as sweet, balanced, and full bodied.  It is balanced in both the intensity of acidity as well as the presence of bitterness.  If we were to take that description and look at a roast curve, we would find a specific part of the roast curve where these qualities are maximized and most prominent in the cup.  For a consumer looking for a dark roast, we can find a place on the roast curve where acidity has been minimized and the characteristic of smoke and roasted flavors become prominent through pyrolysis.

1 - Extreme Light Roast: Peak acidity, lacks sweetness due to lacking sugar development (breakdown of sucrose into fructose and glucose), “underdeveloped”, grassy, vegetal.  Melanoidins are not yet developed, body is thin.

2 - Light Roast: Point where coffee has maximum acidity and maximum sweetness.Bitters from quinic acid are not detectable. Complex acids, fructose, and glucose combine to create identifiable fruit flavors.

3 - Medium Roast: Sugars have began to degrade and break down.Cholorgenic acids are breaking down into bitter quinic acids.High concentration of melanoidins provide malty, pastry-like flavors.Sugars combined with melanoidins create flavors of caramel, brown sugar, baked pastry.Bitters in quinic acid pair with caramelized sugars to create flavors of complex dark chocolates. Some notes of carbon are noticable.

4 - Dark Roast: Acids have largely broken down into quinic acid.Acidity is very low. coffee has some perceived bitter notes and more pronounced flavors of carbon.Sweetness is minimal. Body is heavy due to high presence of melanoidins. Roast ends near, or slightly past, second crack. Some oils may be visible on surface of the roasted coffee.

5 - French Roast: Acids have broken down into quinic acid.Sugars have broken down and degraded.Coffee lacks sweetness and has a strong character of bitter quinic acid and carbon.Coffee beans show heavy oils on exterior and are very brittle.

Connecting to roasting terminology

Before we get into the deeper discussion regarding "roasting terminology", it's important to mention the context where you may find this terminology used.  Describing a roast with terminology such as "cinnamon" or "full city," is a bit archaic in today's modern roasting world.  These terms are based largely on the visual color of coffee, not on a taste profile.  Over the last two decades, coffee roasting has advanced at the speed of light with roasting software and technology.  We no longer roast based solely on visual sight and end temperature.  We can create complex flavors by manipulating roast curves and rate of rise, none of which is really represented in this type of legacy language.  You won't see this language in Hacea educational materials, however we do understand that this terminology is frequently used amongst segments of the roasting community.  I've done my best to try to provide general definitions of the most commonly used of this roasting terminology, as well as real roasting images to accompany them.  There is no clear-cut definition for any of these terms.  No defined start and end point for any of these roast descriptors.  The information provided comes from my 15 years of roasting experience and time spent working within the larger industrial roasters, where this language is more commonly used as a naming convention in technical recipe specifications.  The goal is that this will help provide you with a general idea of what is meant by these terms when you encounter them in your roasting adventures.

While common consumer terminology revolves around a specific set of flavor characteristics, technical industry roasting terminology tends to have specifications that involve drop temperature and ground Agtron readings.  Of note, Agtron is the coffee industry standard scale to measure light (color).  The higher Agtron value, the lighter in color the coffee is.  The lower the Agtron value, the darker in color the coffee is.  Because external color of coffee may be influenced by green coffee processing method, the most common Agtron number used is of ground coffee.  The ground coffee must be ground at the finest possible particle size for measurement by a calibrated color analyzer machine.  In the coffee industry, this roast terminology is often used in proprietary roast recipes.  A recipe would commonly have an Agtron target, which may be measured to ensure roast consistency.  Roast specifications may have a specification threshold of +/- 2 Agtron points.  If a roast falls out of spec, it is an indication that the coffee also does not meet the desired sensory outcomes for the roast recipe.  The following Agtron levels were generated with a CoffMeter A1 Color Analyzer.  The CoffMeter A1 uses Near-Infrared (NIR) LED spectrosocpy to measure the light reflected, and then converts it to the Agtron scale.  Agtron is both a color scale as well as manufacturer of a specific color reading machine.  The traditional Agtron machine is a large benchtop piece of equipment costing between $3,000-$15,000+.  It utilizes a full spectrophotometer to bounce light from an infrared source across the coffee and then uses a complex sensor array to provide a numerical color reading (Agtron level).  

The following information is taken from measurements on actual roasts preformed on a Proaster 1.5kg roaster hooked up to natural gas and roasted at a low (100 m.a.s.l.) elevation.  As roasting is very subjective by nature, these descriptions are intended as a general guide, rather than a set of hard rules.

• Cinnamon - Agtron value 105-125+Correlates to a roast pulled at the very beginning of first crack.  Drop temp somewhere around 370-390°  F.
  

• City Roast - Agtron value 90-104Correlates to a roast finishing with 60-80 seconds of post crack development, with a post crack development rate of rise ranging between 15-10 degrees/minute.  Drop temp ranging from 400-404° F.

• City+ Agtron value 80-89 Correlates to a roast finishing with 80-130 seconds of post crack development, with a post crack development rate of rise ranging between 20-10 degrees/minute. Drop temp ranging from 405-412° F.
  

• Full City Agtron value 73-79 Correlates to a roast that is just shy or at the very beginning of second crack with a temperature range of 413-420° F.

• Full City + Agtron value 63-72 Correlates to a roast that has entered a rolling second crack stage with a temperature range of 420-435° F.

• Vienna Agtron value 55-63 Correlates to a roast that has finished the second crack stage with a temperature range of 430-445° F.
• French Agtron value 30-54 Correlates to a roast that is well past the end of second crack and fully in the stage of pyrolysis with drop temperature over 445° F.  Of note, French roast has a range that goes all the way to near combustion.  
  

Roast levels on the roast curve

Below is a diagram of the roast curve, with images of the beans (from trier pulls) overlaid.  Here you can see where our roast levels begin to match up on the actual roast curve.

The take away

How you decide to identify and describe your roasts is a personal decision.  Using common consumer "lingo" not only helps to make the coffee approachable to the consumer, but also helps the consumer connect with coffees that meet their desired flavor profile.  It is always helpful to remember that the consumer does not have the same interaction with coffee that the roaster does.  The final consumer rarely sees the full spectrum of colors that a coffee roast could potentially have.  They usually only see what the coffee they are going to consume looks like, with no context of other coffee colors.  

When a customer complains about not liking a coffee, it's important to ask "what didn't you like about it?" and "what are you looking for?".  A lot of coffee drinkers may have a preconceived notion in their head that they really like dark roast coffee, but when you dig deeper you find that they want a sweet balanced coffee that they can add cream and sugar to.  They may not actually like the bitter, thin character of a dark roast.  So when they buy a dark roast off your shelf, they think it tastes bitter.  Really, what they are looking for is a sweet medium roast.  Conversely, your dark roast may actually not be that dark.  When the consumer looks at it in the bag, it may look "too light."  But it may have exactly the flavors that the consumer is looking for.  

It is always important for us to remember that the customer is coming to us for our industry expertise.  Rarely are they coming to learn more about coffee, they really just want a good tasting cup of coffee in the morning with as little brain effort as possible.