The best way to determine roast level is by using all five of your senses. One sense alone can’t reliably determine roast level. Just like cooking, coffee roasting is an acquired skill that improves with experience.
There is always a balance between the “roast character” and the “origin character” of the coffee in any roast. In darker roasts, the origin character of the coffee becomes secondary to the flavors of the roast.
It is up to you to navigate the variables of roasting to create the coffee you truly enjoy. The experience of finding the combination that suits your senses only deepens the appreciation for the great variety of coffee available, and the enjoyment of the diverse cup qualities available.
It’s crucial to keep track of your roasts using our handy Roast Log. Roasting is a craft where cumulative knowledge is the goal. Each time you roast coffee, write fill in the Roast Log as best you can and tasting notes. Is it sweet? Does it taste bitter? You can try different brewing methods too; some roast levels are better for certain brewing methods than others. By logging your results you can more easily refer to things that worked and things that didn’t quite turn out how you’d hoped.
Here is a reference chart on how to use your senses to determine roast level followed by detailed explanation for each level:
|Roast Level (see expanded description below)||Sight||Sound||Taste||Smell||Touch|
|City-City+||Splotchy, light brown no oil, no cracks near bean tips, slight expansion||First Crack complete, 0:30-1:30 after end of 1st Crack||Bright, sweet, juicy, light body, fresh fruit||Malty, sweet, floral, herbal||Bumpy, uneven surface, no sheen|
|Full City-FC+||More even, no oil, medium brown, slight cracks at tips, moderate expansion||Just before 2nd crack, 1:30-3:00 after end of 1st Crack||Balanced, bittersweet, medium body, ripe fruit||Chocolate, bittersweet, ripe berry, caramel hints||Smooth, more even surface, slight sheen|
|Vienna-French||Even, dark brown, bigger cracks at bean tips, oil on surface, large expansion||Just after 2nd crack starts up to 0:30-1:00 into 2nd crack||Bitter, thin body, not very sweet, carbony||Roasty, bitter, dark chocolate||Oily, more loss of weight, brittle|
Please note: temperatures given in the notes below are general and relative to the quality and placement of your thermo-probe. They are not the absolute truth for every single roaster. If your roaster can not measure temperature – don’t worry. Use all your senses to judge the sight, smell, sound and more importantly the taste of the roasted coffee.
First Crack: The first of two distinct pyro lytic reactions in roasting coffee, First Crack is distinguished by a loud cracking or popping sound and occurs in most roasters between 390-410 degrees F. It has a sound similar to the popping of popcorn. First Crack marks a rapid expansion of the seed and the point where water and carbon dioxide fracture, leading to the liberation of moisture in the form of steam. This process opens the crease in the bean just enough to release remaining silver skin in the form of chaff.
City Roast Level: This is the earliest palatable stage that the roast can be stopped and result in good tasting coffee. City roast occurs between 415-425 degrees F on most roasters. At this roast level the origin flavor isn’t eclipsed by roast flavors, but the risk is that sourness, astringency, or under-developed sweetness can make the cup unpleasant. City roast generally has a light brown color with strong surface texture, even dark creases in the bean surface, and only moderate expansion of bean size. This varies greatly in different coffees, though. As a very general rule, to achieve City roast the coffee is removed from the heat at the last detectable sound of First Crack, or very soon after, with no development toward Second Crack.
City+ Roast Level: This ideal roast level, also called a “medium roast,” occurs roughly between 425-435 degrees F on most roasters. The coffee has been allowed to develop anywhere from 10 seconds to 1 minute or more, depending on roast method, after the last “pop” of First Crack. These times and heat ranges vary depending on the roasting method and green coffee. At this level, there is a balance between moderate roast flavor and the origin flavor of the bean. Astringent, sour or “baked” light roast flavors are reduced, yet the flavors specific to a particular coffee lot are still expressed in the cup. City+ roasts have a medium brown color and may not yet have the smooth surface that with further development towards Second Crack.
Full City Roast Level: Full City is right at the brink of Second Crack, roughly between 435-445 degrees F. At this roast level, certain qualities of the origin might be best experienced when the roast flavors are actually greater. Many Sumatra coffees fall in to this category. Full City roasts have a much more uniform dark brown color and have a smooth surface from the browning and bean expansion that occurs as the coffee is on the brink of Second Crack.
Second Crack: Second Crack is the second audible clue the roaster-operator receives about the degree of roast. Whereas First Crack sounds like popcorn popping, Second Crack has a faster, shallower patter, much like Rice Krispy’s in milk, electrical sparking, a snapping sound. Second crack is a further stage of the pyro lytic conversion of compounds and occurs around 440 to 450 degrees F. This is a physical fracturing of the cellular matrix of the coffee, and results in an eventual migration of oils from their chambers within the coffee to the outside of the bean. When second crack is volatile, it can blow small discs off the coffee bean!
Full City+ Roast Level: A coffee that’s been roasted just up to the first few snaps of second crack are heard and then terminated, roughly around 445-450 degrees F. The main cue that distinguishes the difference between the Full City and Full City+ is audible, not visual. This is a term Sweet Maria’s basically invented, and while used in the trade a bit, it has its context in our communications with home roasters more than anything. At this level roast flavors begin to dominate, which tones down certain origin characteristics and creates a harmony between the two. This is an ideal roast level for single origin espresso.
Vienna Roast Level: Vienna Roast occurs at the beginning of second crack, roughly around 450-460 degrees F. The Vienna stage (also called Continental) to Light French stage is where you begin to find origin character eclipsed by roast character. If you buy coffee for its distinct origin qualities, heavy roasting is at odds with revealing those nuances. Nonetheless, some coffees are excellent at this stage. Vienna is a common roast level for espresso.
French Roast: Sugars are heavily caramelized (burned) and degraded. This occurs roughly around 460-470 degrees F. At this stage, the woody bean structure is carbonizing, the seed continues to expand and loose mass, the body of the resulting cup will be thinner and lighter as the aromatic compounds, oils, and soluble solids are being burned out of the coffee and rising up to fill your house with smoke. Second crack is well finished
Burnt: By this point, it’s too late, at roughly 470-480 degrees F. You’ve roasted the coffee too dark and will only end up with a bitter cup of charcoal water. The heat being applied for too long has obliterated all of the volatile compounds that might have added flavor and sweetness.
Cooling: The most important thing is always ending the roast when you achieve the desired level – which means how you cool the roast is important. How you got to that point in your roast will affect the flavor of your roast, but as long as you are within a reasonable time frame (which varies, of course) you’ll be fine. At the end of this chapter I will speak a bit more about Roast Profiling, but for now just keep in mind that it is important to track how long your roasts take and how much heat has been applied at different stages of the roast.