Roasting Different Batch Sizes of Burundi on the Behmor 1600+

This blog post is about taking a coffee to the same roast level but at different rates of development. When you think about it, roast level tells you very little about how a coffee was actually roasted. It gives you an idea of exterior color, and perhaps a ballpark on roast range. But that’s about it. Two coffees of identical roast shades can taste quite different, and it’s the roast dynamics that happen along the way that determine how these coffees taste – factors such as batch size, heat changes, air flow, and roast length to name a few.

Using the Behmor 1600+ roaster, my two options for altering roast time are either by manipulating heat settings in manual mode, or by adjusting the batch size. I know I can achieve a relatively fast roast time with 100g of coffee at full power (P5 – 100%), so I decided to go the latter route. Settling on 100g and 200g roast batches for this test, I figured that doubling the batch size would extend my roast significantly. I was not disappointed!

We’ve spent the last week roasting through all of our in-stock Burundi coffees, checking cup quality and looking for where the proverbial “sweet spot” lies in each. While not all benefit from a light and bright approach in the roaster, many of them do, including the coffee I roasted – Burundi Kayanza Gakenke. It’s a dynamic cup when roasted light, and I hoped any differences in dynamic flavors would be obvious in the cup.

Minute by minute roast logs of my 2 test batches

What stands out to me in my notes are roast time and moisture loss. At 200g coffee, Roast #2 went 3 minutes 15 seconds longer than the 100g batch of Roast #1 and there’s less than a 1% moisture loss difference between them. I was surprised how close they tracked given the wildly different roast times. But visually, roast levels looked practically identical. And while 1% is a fairly insignificant amount, the differences in the cup were notable.

Roast #1 had a delicate floral aroma and was tea-like in body and with a tannic finish. A tart citrus hint cuts through complex flavors of clove and black teas…a surprisingly bright cup! Roast #2 was a little less dynamic though far from flat. There were still so many positive flavors noted – Darjeeling tea, chamomile, sweet citrus – but it was as if someone shaved off the crisp edges of flavor definition, producing a much more rounded cup profile.

The flavors evidenced in the different cups seem to support our feeling that Burundi coffees benefit from lighter, faster roasts. When roasted this way, body is light but acidity bright, and delicate top notes are the focus. If I had to choose a favorite, I’d go with Roast #1, but I tend to go for outlier flavors and ‘punchy’ acidity. Roast #2 was still super delicious and I’ll venture to say will appeal to those looking for a somewhat more subdued cup. But honestly, if “subdued” is the goal, you should look elsewhere, because Burundi Kayanza Gakenke is anything BUT “subdued” at almost any roast level.


9 Responses

  1. would love to hear your comments on time, heat variability when using a whirley top pop corn popper to roast . I get a fair variability using the same green beans depending on temp, speeds, batch size with open flame roasting.

    1. Thanks for the comment Fredric! We don’t have a ton of information on roasting with stove top popcorn maker, but Tom did make a nice video tutorial with some pros/cons/tips that you should check out HERE.

      Let me know if you have a specific question and we’ll do our best to answer!


  2. “P3 and fast drum at 1st crack to slow down roast”

    Dan, I get P3 cutting heat in half slowing the roast. I don’t understand how increasing drum speed slows the roast.

    That last is base on my understanding the fast drum speed moves beans higher up in the drum and exposes them more directly to both heating tubes.

    I have come across Sweet Maria’s view (earlier days) of fast drum speed having an aspect of air movement (like adding air to a classic drum roaster), therefore less heat intensity, but I neither understand that aspect of classic drum roasters or how (if?) the fast drum speed of a Behmor is similar.

    I could use some more technical understanding of this than I have. If you can make time, I’ve got an open ended, intensity unlimited interest.

    1. Hey Mike, my notes in this post are a little misleading. Dropping the heat setting to P3 was the main function of slowing the roast. I switched to the faster rpm to keep the coffee higher in the drum and closer to the elements, like you said. I’m not sure how effective this was, but I was doing it to avoid stalling the roast altogether. Since this post, I’ve changed my regimen to include the faster drum speed all the time.

      Hope this helps! I’ll add some clarifying notes to this post.

      Thanks Mike.

  3. It does help, Dan… thank you.
    I roast 151 g. batches (C+ to Lt. V with roast times 9:00 to 10:30, depending on all the vagaries).
    I’ve tended to try to get more time on the roasts with slower drum and lower input early, but that may be me misunderstanding and I should best be doing that later, as you have.
    I’ve not been able to come to terms with Behmor + radiant heating system. It’s almost like (for my range of batch size) the internal temp. is irrelevant. That is, same bean and same progression = ‘same-ish’ total time – roast type – flavor, regardless of room ambient temp (my case is 40 deg. to 80 deg. annual).
    I can say, across the annual room temp roasting same-lot Ethiopiques with same progression to same degree roast (near start of 2nd), internal machine temp at start of 1st crack varies significantly but the time to first, and total time are close… longer with cooler room, but not notably.
    Anyhow… not really questions here as much as me continuing to wonder about things.

    1. Hey Mike, thanks for sharing your observations. I generally agree that it’s tough to get a whole lot of variance in roast progression, unless I really want to slow things down (which I don’t). I tend to enjoy the lighter, brighter coffees and cup profiles, which means roasting just as fast as the Behmor will allow :-).


  4. Early on in my Behmor + life, I messed with the “P’s”… on and off… tweak, tweak. In the end I evolved toward a standard progression. It was easy enough to do given I tend to high altitude beans… just push to 1st. I found in doing that I had what seemed a short start first thru start second for my 151 g. batch size and looked to make it longer… without having to do a lot of button pushing.
    I settled on a 50 sec. drop to P4 2 1/2 minutes in… then back to P5 to either of start first, or an ambient room temp calculated internal machine temp down to P4, 5 to 15 sec. prior to start first. That stretched start first thru start second a little more.
    And I think that short temp drop helps with DP beans… maybe it’s the 2nd DP progression Chris Schooley wrote about… evening out moisture and temp. in the varied size/density DP beans.
    Anyhow… it’s been nice yapping with you, Dan. Thanks for being right there… it’s a treat.


  5. For a long time I couldn’t get good ‘full’ 1 lb roasts out of my Behmor using profiles like P3 which was my favorite at the time. They just took too long. Limiting my weights to 1/2 pound cured much of this and I got what I considered to be nice roasts. I like bright and flavorful smooth but not bitter or over roasted (Folgers for instance… Juan Valdez must have fallen asleep at the switch! Ha!). I have graduated after reading your postings to using my 1st old Behmor with no profiles, just preheating, and it seems to roast to my tastes just fine if I cool after the 1st crack just starts getting going; the heat ‘lag’ takes it to the right point for me. Thanks for all of your informative and educational roasting posts… I’m drinking some delicious Yemeni coffee as I write this although I’ve found your Burundi coffees, especially the yeast process, to be my favorites. Though for mild (and a bit unexciting) I occasionally go with a Brazil bean. It’s all about personal taste isn’t it, and having fun right?

    1. Hey Frank, thanks for the comment and glad to hear you’ve found a roasting method that works for you on the older Behmor! I’m curious if this is the 1st generation 1600, or 1600 Plus? If the latter, you can also roast in manual mode using the highest heat setting of P5. I believe if you’re just starting the roaster on the 1lb setting, that puts you in P1, the hottest preset. It’s a little confusing, because P5 in manual mode is not the same as P5 in the preset profiles. In manual mode, it equates to heat at 100%. At any rate, it sounds like pre-heating the roaster is what’s allowed you to roast the larger batch size the way you want to. That’s fantastic! I too roast by the same mantra of personal taste and having fun. Truer words have never been spoken!

      Happy roasting.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.