Five Things I Learned From Scott Rao’s The Coffee Roaster’s Companion

Huky 500

There are few things as humbling as trying to learn how to roast coffee. It might seem simple enough, but it’s a complex skill that very few people have mastered. Thankfully, coffee legend Scott Rao has finally published his magnum opus, The Coffee Roaster’s Companion. The book is the culmination of over 20 years of coffee roasting experience. Don’t be misled by the slim profile, the content is dense enough to engage a seasoned professional while the style is approachable enough for hobbyists. Over the last 9 months, I’ve read and re-read this book. Sometimes with eager curiosity, other times with frustrated desperation. The book is nicely balanced between technical theory and practical advice. Years ago, Rao’s The Professional Barista’s Handbook was formative for my  barista career.  The Coffee Roaster’s Companion has already proved to be as influential.

Coffee Roaster's Companion

Unequivocally, if you have any interest in roasting your own coffee, you should buy this book. You may not agree with everything Rao has to say, but you will find your own opinions sharpened and informed by Rao’s careful thinking. Here are the top five things I learned from Scott Rao about coffee roasting.

1.  Watch Your Rate of Rise

If you don’t like math, coffee roasting may not be the best hobby or profession for you. One of the most important metrics for mapping and evaluating a roast is the rate of rise (RoR), which Rao defines as “the progression of bean temperature per unit time during a roast.” Essentially, a good roast has a steadily decreasing RoR. Roasts that stall or digress develop unpleasant “baked” flavors. Conversely, roasts where the RoR increases, especially after first crack, tend to lack any sweetness.

Rate of Rise
Image via Cropster

2. It’s all about development

Rao hates the phrase “development stage”, which traditionally is used for the amount the coffee is roasted after first crack. According to Rao, development, i.e. the breaking down of the coffee bean’s cellulose structure, occurs during the entire roast. In fact, the early stage of roasting is crucial for proper inner bean development. “Low and slow” might be the secret to good barbecue, but coffee needs a large amount of energy upfront.

3. Minimize use of the trowel!

There’s nothing like taking out the trowel and inhaling all of those amazing aromas that occur during roasting. But according to Rao, it’s the last thing you should do. Using the trowel decreases temperature stability in the roaster, and ensures the coffee in the trier is not going to follow your desired profile.

Editor’s note: The Coffee Roaster’s Companion does not contain the above information, but was inspired by talks that Scott Rao has done. We regret the error. 

4. Increase the airflow as the roast progresses

The higher the airflow, the higher the convective heat transfer (as compared to conductive heat transfer.) As such, airflow should be gradually and incrementally increased as the roast goes on. This dispenses of the smoke and chaff that are produced late in the roast. According to Rao, smoky flavors in the cup are a sure-fire sign airflow was set too low.

Coffee Roaster's Companion

5. Cupping is King

The best way to evaluate your roasts is cupping. Developing a palate that can identify roast defects is one of the most important skills a coffee roaster can possess.  This only comes from extensive, thoughtful tasting. Worth the price of the book is the chart on page 65, which maps unpleasant flavors with certain roasting errors and how to fix them.

If you’re fortunate enough to have access to a refractometer, Rao recommends cupping at the same extraction percentage as your ideal brew. If you’re not able to get the extraction percentage you wanted, this is an indicator your coffee wasn’t sufficiently developed.

For more information on cupping, check out the Specialty Coffee Association of America’s cupping manual.

17 thoughts on “Five Things I Learned From Scott Rao’s The Coffee Roaster’s Companion

  1. There’s a recent thread at HomeBarista on the effect of the trier (trowel) on the roast. A post there refered to this article/blog post. Now, I take it that “3: Don’t touch that trowel!” is a piece of knowledge that you’ve derived from your own experience with your Huky. I’ve just scanned through the book again and found just about nothing where Scott Rao states that you should not use the trowel.
    I’m not trying to flame you, as what you say kind of makes sense. (B.t.w. I use a Huky 500 roaster myself, for the most trying to adhere to the 3 commandments…) I often find myself not having used the trowel over several roasts, simply because I didn’t find the need for it. Also, using the trowel all the time probably affects heat distribution and airflow. 5-6 times during a roast is another story. But stating that Rao says so is your own intrepretation, not a fact.
    Two scenaios. First the beginner roaster. For him/her it’s (IMO) good practice to use the trowel quite a lot, to get the feel, smell and touch with the progressing roast. Second, computer or thermocoupler failure… If so, the trowel and a timer are your best friends.


  3. To Mr Michael Butterworth,

    Having read Scott Rao’s book thoroughly, I am confident that he does not suggest avoiding using the trowel. To attribute this claim to him in your article destroys your credibility as a coffee professional. Why did you decide to do this?

  4. While I didn’t advise against using the trowel in The Coffee Roaster’s Companion, I have publicly advised several times against using the trowel. It’s possible Michael heard me say that and thought it came from the book.

    I don’t think pulling the trowel ruins a roast; however, unless one is at the last moments of a roast, using the trowel seems to offer more cost than benefit.

    I only use the trowel when I’m charging hotter or beginning a batch faster/hotter than usual, and I want to check for potential burning 3-4 minutes into the roast. I also use it on occasion in the last 10-15 seconds of a roast, particularly with a coffee I’ve never roasted before.

    These are just my opinions, and I have no data to prove using the trier damages roast quality. It just seems prudent to avoid using the trowel often.

    1. Thank you Scott for clarifying your position and James et al for bringing my error to my attention. I’ll update the post to reflect that The Coffee Roaster’s Companion does not contain this information.

  5. It’s an interesting read but it should really be re-done and expanded a great deal. This is a good primer – at 90 pages. Please bear in mind the primary section on roasting is actually only 25 pages – including a bunch of photos and graphs. This one area could (and should) be far more in-depth with lots more examples. Refractometers are mentioned as an essential tool – basically just one paragraph – but nothing whatsoever about how to actually use one.

    Think of this as a “useful guide” – it will certainly help to avoid key mistakes but this is definitely not a comprehensive and authoritative work.

    What I’d like to see is a membership site instead of a book, so we can pay for access to see a lot more info and a shared community of experience.

  6. John,
    I appreciate the feedback. I’ll defend my book a bit, though, by pointing out that it is very dense– I try not to waste words, while most “how to” books are really 3-page essays stretched out to 100 pages. Illy’s espresso book is wonderful, but has exactly zero pages of practical advice on coffee making.

    It’s also, frankly, the only book to ever contain practical, accurate, concise information about roasting. It’s a more difficult task than most critics seem to understand– editing information down to what is practical and universally applicable was challenging… I could have written 300 pages on roasting, but most of it would have confused readers because they would have to understand how to adapt the information to their particular machine. I realized during writing that the more prescriptive I made the book, the more readers would misapply the advice. As it is, most readers have distilled the book’s 100 pages to “DTR should be 25%” and seem to have ignored the other 90 pages.
    My email inbox is a testament to how complicated roasting is for most, unfortunately. Perhaps you would have eaten up a long, complex book, but 90%+ of roasters weren’t ready for it. Perhaps in time I can work on such a book.

    Regarding refractometers, the two reasons I didn’t write more about them were that my other books already discuss refractometry, and a refractometer has only one role in roasting: to warn of gross underdevelopment. There are better ways than a refractometer to examine roast development.

    Your idea about a membership site is interesting– I’ve considered it many times but have assumed there wouldn’t be enough interest to make it worth my while. I may explore how much interest there is for such a site. Thanks.

  7. I have been roasting for a small coffee company for 6 years now. The roaster was a Diedrich IR-12, and I was never really taught any roasting theory. We tried to keep all batches (18 lbs max/6.4.lbs minimum) to 15 minutes or less. scorching/tipping/pop-offs were things to avoid, but what does each refer to.

    Now we just moved from the IR-12 to a CR-20. I am like a child thrown into the gauntlet. Every batch seems to show signs of (what I would call carbonization/burning…small brown spots in the early parts where the bean is light tan to dark tan, blackened spots after 1st crack, but not immediately)

    Boss/owner was taught by Steve Diedrich when he bought his original roaster (not the IR-12, the original roaster before the IR-12) but he {the owner} isn’t into teaching.

    Would love to be able to have insight into wtf I’m doing, not for the owner, but for the person who drives all of this action: the customer. If I have a weakness (question in an interview) it’s the desire to please. I want people to enjoy what I do.

    Please let me know if you think your book can help me Scott. Amazon has it new for $99.99 and used for $2044.00.

    Not ashamed to say (with regards to the pricing at amazon) f*%#ing confused, but hungry (with regards to wanting to rise to the level that the producers and consumers deserve.

    1. In my opinion, any professional coffee roaster would benefit from reading this book. Also I think you can get it for cheaper than that directly from Rao’s website.

    2. Scott has it for $45 on his own site – yes it’s worth it. He also does consulting, which your boss should pay for …

  8. Hi Bill,
    Yes, you can get it from my site for $45. (thanks MIchael)
    On the Diedrich: I recommend you try charging with 50/50 air and possibly shifting to 100% air about halfway through a roast (depends; these days the Diedrich fans are so powerful that 100% is often too much)

    It’s odd that you’re getting tipping, etc. If you’d like, email me and tell me your drum RPM. It could be the problem. IF not, it should be easy to figure out.

    [email protected]

  9. Hi Scott,

    I apologize if my initial post came off a bit hard – it wasn’t my intention. I very much like the book and want more, even if only 5-10 more pages addressing roasting technique. For instance we would really benefit from a bit more clarification and examples is to elaborate on the discussion on the 4 roast profiles. The yellow is generally good and the others have issues of one kind or another (flat, rising ROR later in roast, etc).

    What I feel is missing here is the typical corrective actions that we would take in “the next roast” or even “roast in progress” to reduce or eliminate each of the undesirable ROR curve characteristics. Similarly, you mention that some action should be taken a bit before 1st crack to address the evaporative challenge but didn’t discuss what one would usually do about it.

    Would you mind briefly touching on these, along with whatever assumptions must be made (gear, features, etc) as a general answer may not apply well for everyone?

  10. I am roasting on a newly purchased Hottop 2k+roaster and the Artisan program running on my Mac (so I can see the ROR, etc.), how much of Rao’s book would apply to my process? You serious roasters are using much bigger roasters but the process is really the same, so….?

    charlestown, indiana

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