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If any of you are familiar with the local coffee chain in Yokohama Japan, called Coffee Tonya, they have this speed roaster that roasts the beans you choose from their great selection of beans from around the world. I'd never seen one before, and I'm not familiar with the machine, so I'm not sure if the design and make is proprietary. But the roaster can roast the green beans to your desired roast in nearly 2 minutes flat & that is quite impressive, since you can choose from a light to dark roast gradient. I've purchased beans from a branch in the Philippines, had about 250g of Brazilian beans city-roasted (on the dark side), and must say that the result delivered a balanced flavor, without too much bitterness in the brew, creating a good bloom (pour over) &/or crema (Bialetti Brikka), and a pretty good expression from the roasted bean.

I wanted to ask if anyone is familiar with the process of this quick-roasting style, and if there are any inherent differences that could come from this speed-roasted bean, as compared to a more traditional slow-roasted bean.

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Roast times can significantly affect coffee flavors, and a 2 minute roast profile is concerning. While I cannot say I am familiar with the process they are using, I do know a decent amount about the chemistry involved when you are roasting a coffee bean. My biggest concern would be internal development of the coffee bean.

To give you a brief run-down of roasting, without spending hours on this post..

You typically have two types of heat in roasting, conductive and convective. There are disagreements on how best to apply heat to a coffee bean, but the traditional understanding is you apply conductive heat early in the roast and convective at the end. The reason is because if you do not dehydrate the internal bean, you will get an insulating barrier of zero moisture encapsulating the moist interior of the bean that will result in underdeveloped flavors (sour, acidic)

If you apply too much convective heat early on, then this will typically happen. If you apply too much conductive heat, you usually get what is called tipping which can be seen on the ends of beans as a small black spot where the plant would actually sprout had the bean been planted (this is a natural weak spot in the cellular structure that allows the plant to sprout).

To roast a coffee bean from room temp to ~400F give or take 25 degrees in 2 minutes would require an average rate of rise (RoR) of 115 degree / minute. To give you an idea of the difference, The highest RoR I typically roast at is about 36 RoR and maybe an average RoR of 15 or 20.

My initial reaction to application of heat so quickly to a coffee bean would be that you would get over-roasted on the outside with possible tipping, and an under roasted interior resulting in sourness.

I know that timing on airbed roasters is different from traditional drum roasters, but I've never heard of them doing 2 minute roasts either so I am guessing this is a proprietary roasting system of some sort. That being said, if you want a pretty in depth discussion on how roast times affect flavor you can check out Modulating the Flavor Profile of Coffee by Rob Hoos. He gives a very thorough break down of what happens when you trim as little as 20 seconds off a given segment of a roast profile and how that affects the flavors in coffee.

(btw, if I deviate from my desired roast level by more than 45 seconds, the beans usually end up in the trash can because I refuse to sell them)

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    One other little comment, as coffee roasts you there are flavor compounds that are created, and then recombine as the roast develops. Just from a chemical perspective, I can't imagine getting the same chemical diversity in a coffee roasted in 2 minutes vs. 11 minutes. The Maillard reactions can't happen until after the beans dry which in a traditional roaster takes about 4-5 minutes, so presuming you accomplished this in 60 seconds which is insane, you would still only get 1 minute of development vs. 6-7 minutes of development in traditional roasting.
    – Nate M.
    Jul 11, 2017 at 15:08
  • I would imagine that a speed roasting process would have it's adverse effects on the bean... to your point about airbed roasters, I did notice (since the machine has a glass enclosure) that the heating process also involves having the beans thrown about, (almost like molecules in a microwave). I would imagine the roasting is probably more of a novelty than an entirely new way of roasting. See the photo here: oi63.tinypic.com/allpc5.jpg
    – farankoshan
    Jul 12, 2017 at 7:01
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    That kind of reminds me of a sonofresco roaster, but even that has an average roast + reset time of 15 minutes based on some rough napkin math of their stated roaster output per hour. Granted if you took the same machine and loaded it with 200g instead of closer to 900g you would probably end up with a 5 minute roast. THat may be how they are accomplishing a 2 minute roast.. Although I still wouldn't recommend =p
    – Nate M.
    Jul 12, 2017 at 20:33

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