Judging roast from whole bean is hard: Try grinding the coffee to compare the roast level!
The exterior and the interior of the roasted coffee bean might be holding valuable information in terms of their color and appearance.
Here is a comparison between roasted coffee surface color, surface texture and ground coffee samples.
What you can see is that this coffee, our special 2006 selection of Costa RicaCosta Rican coffee is typically very clean, sweet, with lots of floral accents. hey are prized for their high notes: bright citrus or berry-like flavors in the acidity,... ...more PeaberryA peaberry is a green coffee "bean" that has a rounded form: Coffee is the dried seed from the fruit of a flowering tree - each fruit having... ...more from Dota, Tarrazu, has a lot of surface color patchiness, and a lot of surface texture at the lighter City roastCity roast is what we define as the earliest palatable stage that the roast process can be stopped and result in good quality coffee. City roast occurs roughly... ...more (first crackFirst crack in one of two distinct heat-induced pyrolytic reactions in coffee. It is distinguished by a cracking or popping sound in the coffee, and occurs between 390... ...more completed, roast progress stopped immediately, 426 degrees finishSimilar to aftertaste, but it refers to the impression as the coffee leaves the palate. Aftertaste is the sensations gathered after the coffee has left the mouth. We... ...more temperature as measured on the Probat L12 roaster. Keep in mind these pictures are taken under 4 strong lights on my photographic copy stand, so in “normal” lighting the surface blotches would not be so extreme, and the overall roast colors would look darker.
Surface texture influences how you perceive color. So even the fineness of grind influences color perception. Notwithstanding, ground samples provide a much clearer method of evaluating color, which is why roasters use ground samples when implementing a color measurement system like AgtronA machine and a color matching system used for quality analysis generally in the food industry, and specifically in coffee: Agtron spectrophotometers are used in the coffee industry... ...more, or the like.
The light source, both its intensityWe have a simple scale to rate intensity in our coffee reviews, from Mild to Bold. Low intensity does not mean low quality!: We have a simple scale... ...more and reflectivity, are very important to judge coffee. The color balanceSuggests a harmony and proportion of qualities, and implies mildness since no one quality dominates.: Balance is both an obvious and slippery taste term. It implies a harmony... ...more of the light source is important too, especially as “warmer” light tends to lead to an impression of darker browns.
Here are swatches taken from the same photo above. Note the extreme difference in patchy surface color from lighter to darker roast. This specific lot of coffee is quite nice at the darker roast levels (pungentRefers to an aggressive, intense aroma or flavor, often related to spices (pepper) or roast tastes. Pungent foods are often called "spicy", meaning a sharp or biting character,... ...more spicey/pepper notes with intensely tangyAn adjective modifying a flavor descriptor, describing a sharp effect; tangy citrus, tangy bittersweet flavor, tangy green apple. ...more bittersweetBittersweet is from the language of chocolate, and describes the co-presence of positive bittering compounds balanced by sweetness. It is directly related to caramelization, but has inputs from... ...more chocolateA general flavor or aroma term reminiscent of chocolate. But what type? Usually described with more specifics.: Chocolate is a broad, general flavor or aroma term reminiscent of... ...more).
But it is at the “ugly” City roast where this coffee has true Dota Tarrazu “originIn coffee talk, it refers to a coffee-producing region or country; such as, "I was just at origin." Of course "Origin" for most product we use is not... ...more character”, i.e. wineyA taste term to describe a wine-like flavor with a similar perceived acidity and fruit, and some level of acetic acid. It is found most commonly in East... ...more fruitedIn some coffee taster’s lexicon, “fruity” means the coffee is tainted with fruit, and “fruited” means a coffee is graced by positive fruit notes. We don't exactly see... ...more notes with interesting almond and hazelnut roast tasteThe set of flavors that result from the degree-of-roast.: Roast Taste is a term we started to distinguish it from "Origin Flavor". We use the "roast taste" term... ...more, grape, grape skins in the finish, cherryEither a flavor in the coffee, or referring to the fruit of the coffee tree, which somewhat resembles a red cherry.: Either a flavor in the coffee, or... ...more. Roasting is not a beauty contest, and many commercial and home roasters make the mistake of roasting coffee until surface texture is even, and variation from seed to seed is more uniform.
You need to roast it for cup flavors, not for roasted coffee appearance. What that specific cup character is, you decide. But at the Vienna roastVienna roast occurs at the beginning of second crack. The Vienna stage is where you begin to find origin character eclipsed by roast character.: Vienna roast occurs at... ...more pictured above (448 f finish roast temperature in the Probat L-12), tangy roast notes have eclipsed the “origin flavors” of the coffee.
I would also say that this lot of our special peaberryThe Spanish-language term for Peaberry is the same for "snail". See Peaberry for more information on the single bean fruit of the coffee tree. A peaberry is the... ...more selection is less uniform than even I expected … but I was happy with the cup, and that is what counts! Coffee makes your constantly overcome your prejudices and re-evaluate your own “received wisdoms” when it comes to judging cup flavors.
While roast level can be hard to judge empirically, you can create your own set of saved samples and use them for future roasts. It’s a better way than buying a $4000 color analyzer or a set of SCAA Agtron roast color disks:
Here are some other pages discussing degree of roastDegree of Roast simply means the roast level of a coffee, how dark it has been roasted.: Degree of Roast simply means the roast level of a coffee,... ...more:
I am kind of a novice, but am really enjoying your beautiful and informative website. Thank you very much!
Steve in Rohnert Park
Thanks for the note Steve! I’m glad to hear your finding our site useful and informative. Don’t hesitate to drop us a line if you have any questions.
I come back to this site often to review and keep myself up on coffee knowledge. This is, in my opinion, the best that can be found on the internet. Thanks so much for sharing with us who want to understand and experience the best coffee we can brew. I seem to be a perpetual coffee novice but keep trying to get to that perfect cup of coffee. Roasting will probably be my next adventure. I have my doubts that I can equal what the professionals accomplish, but I want to try.
All I can say is, don’t wait any longer to start roasting! (after a couple of tries) you won’t believe what an amateur can accomplish!
Always appreciate what you do.
I have a question. You show color and temp of the bean while going through the roasting process. How do you measure the bean temp?
Usually we are using a thermocouple probe. Like this: https://www.sweetmarias.com/k-type-thermocouple.html
It is used with a digital thermometer, which we are actually out of stock on, but it will be back in a week or so…
This type of probe, when placed directly into the coffee mass while roasting is really responsive … but they don’t last as
long as the type that is inside a metal housing. Those types tend not to be as responsive.
Anyway, they key thing here is that we are measuring a contact temperature, and that’s always going to be a little variable, because it will be measuring the environment too. Some people talk about “bean temperature” but there isn’t a way to measure what is happening internal to the bean during roasting. You can use a no contact IR thermometer, which can work well too, but you have to hold it and aim it at the coffee….