Roasting coffee

Has anyone successfully roasted green coffee beans in an oven?

Man John, I have not. So far I've only roasted green coffee beans in a cast iron skillet, but having to stir pretty dang constantly in order to keep flipping them over to roast each half (and roasting this way STILL seems so easy to burn/overroast any given amount of beans).

I've also used an old air popcorn popper (the plug-in electric kind, called "Popperie" or something like that). That does alright, but very small quantities, and given that each popperful can take 10 mins or so, or longer in the winter, yeah, it's not really the way to go for any reasonable quantity.

Then I have also gotten to use a propane-burner rotisserie style setup. Honestly this latter so far might be my favorite as it roasts pretty evenly and continually, and it constantly spins and dumps the mass of beans around and around and around. It also does better at getting a hot mass of air in and around each and every bean, roasting all areas of each bean a lot better than say the cast iron skillet. I myself haven't bought any kind of rotisserie style roasting setup for myself yet though, mostly because of..............money.

Hi Cody,

I have used a caste iron skillet as well as a stove top popcorn popper. I recently ran into a reference to oven roasting. It makes sense in terms of maintaining a steady temperature. I have run into references to 275f for 20 minutes …and various variations on that .

I agree with everything Cody stated.
I also tried roasting in a cast-iron skillet, and I got the same results.
A popcorn roaster was suggested, but since we are off-grid, we do not use electric heating elements.
A rotating pan heated with propane would be closest to how my coffee roaster in Sandpoint cooks his beans.

Give the oven a try, John, and let us know how it works.
I wonder if you need to stir it while baking?
Are fresh green beans lower in cost?
I would guess that a green bean would store longer than a roasted bean.

The no stir part is what attracts me….as well as the opportunity for consistency with outcomes.

I used to be able to buy green coffee in 25 pound bags pretty cheap compared to the grocery store prices. A recent search was depressing. Of those sources I checked, bulk green prices may have been a little higher … hard to tell with today’s prices.   It was just about impossible to find a 25 pound bag.

I haven't had green coffee beans in a while.
I do remember always roasting in my dutch oven and just planning to stand there stirring for a long time ....up to a half hour?
There was a 'first crack' sound to listen for and the glossiness of the beans when they begin to release oils.  'second crack' was a darker roast... have forgotten all the nuances and observations along the way but seems like roasting in the oven would make things hard to judge?

I do remember it filled the room with a not very pleasant smokey smell...I thought roasting coffee beans would smell wonderful🙄

I would have kept it up because it made delicious coffee but the green beans were hard for me to find and did get more expensive.

I just checked on a 25 pound of  Brazilian coffee of unknown quality at around $7.50 a pound. I have a can of Folgers at $18.00 for a little over 2 pounds.  So $15 vs 18.  But there is shipping to tack onto that lower price.  Given the variables, I am not too excited.

Edit:  I just found Colombian for around $6.50 a pound..shipping included …in 65# boxes.   While I do like coffee, I have to wonder how long it will take for me to go through 65 pounds…and what flavor that final cup might have.

A while back I bought 100 used coffee sacks. I think they cost me $20 plus shipping and it's one of the best micro investments I ever made. Sometimes when I got out a fresh bag there would be a handful of green coffee beans left in the bottom, so I got to wondering about how to make the most of those.

I got out my cheapo heat gun and a stainless steel colander, and went to work. The results were impressive, and I learned a few important things:

1. Always do this outside. The smell is not all that nice thanks to the skins coming off the beans and burning.

2. The skins fly around and go everywhere.

3. Keep the beans moving around and watch for the oils to accumulate on the surface as well as the colour. This is how you control the darkness.

4. Don't try to do too much at once. My best batches were a couple of handfuls, maybe a cup at most.

When I worked at the local coffee shop, where the owner roasted coffee in-house, and sold as much wholesale as resale, I learned a few little things (not enough, but any means, to truly *know* the art of it), about roasting. One of the things that I learned has had me thinking about getting a second popcorn maker, like this one:
https://www.amazon.com/Elite-Gourmet-Electric-Measuring-Reversible/dp/B09226X5TK/ref=mp_s_a_1_7

We have and love our first one, for popcorn - but I've been thinking about one dedicated for coffee roasting, because it's very much like a mini (micro?) coffee roaster, in the constant stirring feature. The bowl would contain the shells, and the clear top would still allow one to see the stage the coffee is at in the process. The 'butter vent' in the top can be uncovered, allowing for a full 'nose', to discern the doneness.

*IF* I'm remembering correctly, according to Kenny (I can't ask, as he passed away a few years ago)
Right after the 'first crack' is a 'light roast'.
A few minutes later, but before 'second crack' is 'medium roast'
And, right after 'second crack' is a dark roast, with a few minutes longer being the French roast - my personal favorite.
But, Kenny only used those points as a basic guideline - the rest was by the 'nose'.

If you're able to find one, a local coffee bean buying co-op would be able to get the best prices, because of the volume discounts, and would likely allow its members coordinated access to different coffees from around the world. Kenny loved to scout the planet for different coffees, and working for him was a fun & fantastic boon to my coffee knowledge and palette. He is the reason I have 4 grinders and a decent espresso maker, lol.

I think constant stirring is essential for a uniform roast, which is why coffee roasting machines use either a rotating drum or air blast (for very small batches). I've used both kinds successfully, but they had disappointingly short lifespans, even including repairs. By the time my second Gene Cafe drum roaster quit working reliably, Costco was carrying my favoured Sumatra bean roasted to the degree my wife and I like, so I gave up roasting. Our conical burr grinder was a very modest cost and has been reliable, needing only burr replacement after grinding a bean-sized stone, quite the opposite of my roaster experience.

I have not tried oven roasting, unless it was a long time ago and not repeated. I used a real old yellow black and cream air popper and it was serviceable but messy. It did not last long with the extended usage for roasting coffee. I got a commercial glorified air popper coffee roaster, and it worked well after being modded to give control of heat and air flow. It also burned out. I settled on a simple Whirley Pop stovetop popper. And it was fine. The only mod was to slightly enlarge a hole for a thermometer to fit into, and I got a picnic tablecloth springy hold down clamp. I drilled it to accept the thermometer so it did not collide with the stirrers. I was able to do all the roasting stages, and if I was careful to nail down all the variables, I got reproducible results.

I was going to make a snide comment about Folger's and its alleged relationship to coffee, but my coffee snob days are over. Having lost my underappreciated taste for coffee in my late sixties, I resort to a bastardized cold brew, adulterated with a pinch of salt, 2 t maple syrup, and a splash of fat -- Full Fat Oatly in my case. The fat is the critical piece. My former self would be horrified with what I have done to the sacrament of coffee!

I think the air popper I used was the West Bend. Not all air poppers are up to the task. Here is one guy's take, which sounds pretty informed to me"
The Popper Crop

In a nutshell, no. Putting your coffee beans in the oven will bake them, not roast them. Another comment was correct, that there has to be agitation and high constant ambient temperature to get bring coffee beans up to temperature as quickly as possible. There are two methods. Standard drum roasters, and fluid air bed roasters. The cheapest fluid air bed roaster you’ll find, is the air pop popcorn poppers. Say that 10 times fast lol. I could give a master class on the signs and smells, you need to look for to ensure that your coffee is roasted to the desired level, but the information is easily found online. Also, let the coffee off gas for at least five days before you grind it and drink it. Otherwise it will taste insipid and weak. It takes time for the flavors to develop. If you keep air away from it, it will still be considered fresh for a month after offgassing. I don’t make any money from recommending businesses that I love, but if you want to cut out the middle man and have a few Dinero to spend, there’s a company called. Sweet Maria’s that will take care of your needs. Or as others have said, just find a local source for green coffee beans, and don’t let them overcharge you too much. If it’s a standard Guatemalan, Colombian, Kenya, they shouldn’t be charging any more than five dollars a pound.

J

John F Dean wrote:Has anyone successfully roasted green coffee beans in an oven?

A couple of other pro tips. Once you roast the beans to the desired level, they have to be cooled off very quickly. The easiest way is to toss them into the air repeatedly in a colander. Another method of roasting beans via the fluid air bed method is to use a heat gun. Very carefully. That’s how gourmet coffee Byers roast beans on site to determine which lots they’re going to purchase. Yes, they grind it and brew it immediately, and it is insipid, but their professionals and they know what characteristics to look for to ensure that it’s going to be fantastic once it off gases. You don’t have to have that skill.

J

John F Dean wrote:Has anyone successfully roasted green coffee beans in an oven?

A caveat, sorry about this. But since I recommended a business and gave generalize pricing, I have to eat crow. It’s been a while since I placed single orders with them, and prices have doubled over the last couple years. I buy 5 pounds a month from them with a deal where they choose the coffee as they send you, and keep costs low. It’s still cheaper to buy a green and roast your own than it is to buy the horrible stuff in the grocery store.

J

John F Dean wrote:Has anyone successfully roasted green coffee beans in an oven?

J Garlits wrote:In a nutshell, no. Putting your coffee beans in the oven will bake them, not roast them. Another comment was correct, that there has to be agitation and high constant ambient temperature to get bring coffee beans up to temperature as quickly as possible.

This jibes with what I've learned from living here in coffee country and roasting. No agitation to me seems like a recipe for disaster.

I disagree with other comments about it being a terrible smell, to me it's one of the best things about living in a place where many people still grow and roast their own-- a fabulous smell. Maybe once it burns the smell gets worse. Then again I like natto, stinky tofu and love a mechanic who at any given moment smells like a gas station, so maybe my taste is not to be trusted....

I’ve done a fair amount of coffee roasting (personal, not commercial) over the last decade and a half and there are multiple ways of doing it. Just recently experimented roasting a pound of raw coffee in a hand crank popper on my stovetop. I kept the heat fairly low and cranked it the whole time, but it wasn’t particularly arduous and ended up being a pretty good roast. I used a stainless steel version from amazon.

I have used a stove top popper as well as a skillet. The oven approach got my attention because it seems to involve the lest work.  Now, I am tempted to try an electric popper from a junk store.

Whirly-pops are awesome! The agitator at the bottom does a great job with coffee just like it does with popcorn. And when you say "low temp" as you know but other readers might not, is that the bottom of that whirly-pop will quickly get to 450 degrees even on low heat. With methods like this, you have to realize that you won't reach perfection because you can't control all the elements (ambient temp, airflow, etc.) but if once you get the hang of it, it'll knock the socks off of anything you can get at the grocery. Unless you burn it to a crisp, even the worst home roast will outperform anything you can get at the store. That's like saying your worst day hiking in nature will be better than your best day at work, but it is generally true.

j

E Eyring wrote:I’ve done a fair amount of coffee roasting (personal, not commercial) over the last decade and a half and there are multiple ways of doing it. Just recently experimented roasting a pound of raw coffee in a hand crank popper on my stovetop. I kept the heat fairly low and cranked it the whole time, but it wasn’t particularly arduous and ended up being a pretty good roast. I used a stainless steel version from amazon.

I'm over-posting on this thread. Sorry John! But here is another tip.

Roasting coffee goes through several stages. Estimate or confirm that your roaster is at about 450 degrees or slightly lower. Add the beans and agitate. If you can see the beans, they'll start to turn some shade of brighter green than they were when you added them. When they get to that point, it should smell very grassy. If you smell it, you'll know what I mean. Then they'll start to turn a nice shade of green/light brown. Keep agitating and keep the temp constant. Once they begin to turn truly brown, wait for "first crack" where the internals of the bean expand and "snap the spine" of the whole bean. If you've ever sat around a fire pit and the wood crackled and shot sparks into the air, it sounds like that. It will begin sporadically, then at its height, it'll seem all the beans are cracking at once. That will die off and there may or may not be a pause between first and second crack. It might be up to a minute, or it may overlap a bit. Second crack isn't as loud, and it sounds more "ping-y." That is the best way I can describe it. It's pieces of the outer surface of the bean detaching due to the extreme heat, and formation of oils on the outside of the bean. If you like lighter roasts, stop the batch midway through first crack to its completion. If you like darker roasts, let second crack complete, then cool the beans. Watch the level of smoke. Going into second crack, you definitely want to be doing this outside. Up to the middle of first crack, you can do it inside if you and your housemates don't mind a LITTLE bit of smoke and a nice roasty smell. Into second crack, balance out the sounds with the smoke level to determine when the beans are done. If you smell smoke from roasting beans, you'll learn by experience how that differs from beans that are burning. Burning beans have acrid smoke.  

j

John F Dean wrote:Has anyone successfully roasted green coffee beans in an oven?

We have been roasting our own coffee for nearly 10 years. We started out using a stove top Whirly Pop popcorn maker, which worked really well, but eventually I got tired of all the cranking so I bought a Fresh Roast home roaster which has been great. It still requires attention, but it is basically only a 10 minute operation, and the payoff is worth it. We love the taste of fresh roasted coffee!

John F Dean wrote:Has anyone successfully roasted green coffee beans in an oven?

We roast 7# of coffee every month in our earthen bread oven. We get our green beans beans from

https://copantrade.com/products/honduras-shg-ep-organic

We usually buy a  couple 25#  bags at a time and roast it to second crack (dark roast).  We usually roast at around 800 degrees F.

We roast 3 - 2 ½ # batches of coffee about once a month in a cylindrical basket. I tried to send a couple little movies but this board wouldn’t accept them. Let me know if you’d like me to send a photo of the basket or bread oven.

William Haines wrote:
We roast 3 - 2 ½ # batches of coffee about once a month in a cylindrical basket. I tried to send a couple little movies but this board wouldn’t accept them. Let me know if you’d like me to send a photo of the basket or bread oven.

It would be great to see pictures of your setup. A simple, effective way to roast that much coffee sounds really interesting.

Unfortunately I have just finished packing my coffee roaster away as I am retiring and moving in a couple of months and had roasted my green beans in readiness to last until after the move.

I have never used the oven as I felt I wouldn't be able to turn the beans enough and still keep the heat correct for optimal roasting.

Instead my son converted an old Sunbeam bread maker we found on a waste collection pile out front of someone's house we were passing over 10 years ago. Hopefully when I move I can post a pic of the converted roaster.

Since green coffee beans can keep many years just fine it gives me the option of buying many different kinds of bean and creating single or blends of flavors and aromas I prefer when they are on sale.

I only ever roast enough to see me through 10-12 weeks as after roasting quality quickly deteriorates. I only grind these amounts when I am ready to use them also for deterioration
reasons.

My son screwed a holding bracket to the side of the bread maker to hold a heat gun positioned directly onto the green beans. A fan is placed at the side of the bread maker and keeps going during the process. As the beans oscillate (turn) in the bread maker they get even heating and cooling happening. We listen for what is called 1st crack, then wait for 2nd crack when the beans are about ready - First Crack vs. Second Crack: Light/Medium roasts are defined by the first crack (popping sound), while Dark roasts reach the sharper, louder second crack.. FYI Roasting beans smell yuk! You will need a resealable foil pack to store the beans in for a few days while the gasses burn off then the beans can be stored as you would usually before use

There is a colour chart online that you can refer to as to how dark or light you want your beans to be. It also explains whether it will taste light, mellow, dark, and the bean overtones you can experiment to get, caramel, chocolate etc. I used a site called coffeesnobs.com.au for a lot of info on how to treat my beans but only ever bought a couple of times from them because their prices were too high, you can shop around for better bargains in your own country.

Key Roasting Color Stages
Green: Raw bean, room temperature.
Yellow/Yellow-Tan
Moisture loss stage, develops a toasty or bread-like smell.
Light Brown
Maillard reaction occurs, beans expand before first crack.
1st Crack
Light brown color,, pronounced acidity, "City" roast level.
Medium Roast
Medium brown color, balanced acidity and body.
Medium-Dark
Rich dark brown, oil begins to appear, "Full City".
Dark Roast
Dark brown/shiny black, oily, "Vienna/French" roast, low acidity.

Commonly Used Roast Categories
Light Roasts (Cinnamon/New England): Pale brown, high acidity, non-oily.
Medium Roasts (American/City): Balanced, brown, widely used for drip coffee.
Medium-Dark (Full City): Rich, dark brown with some surface oil.
Dark Roasts (Vienna/French/Italian): Shiny black/dark brown, bittersweet, smoky.

We had fun trying light to dark before choosing what would be our daily use one and our special occasion blend.
Great fun and well worth it once you get into the routine, compared to store prices and freshness. It is definitely more successful than an oven or any other method that isn't able to turn your beans while they are roasting.
Hopefully any of our talented permie DIYers on here can give it a go and post their pics.

I remember reading an article by Ashley Adamant on her site: Practical Self-Reliance.  I just looked it up and searched for coffee.  Here are the results:
https://practicalselfreliance.com/?s=coffee
She has everything you can imagine and then some!

William Haines wrote:

William Haines wrote:

John F Dean wrote:Has anyone successfully roasted green coffee beans in an oven?

We roast 7# of coffee every month in our earthen bread oven. We get our green beans beans from

https://copantrade.com/products/honduras-shg-ep-organic

We usually buy a  couple 25#  bags at a time and roast it to second crack (dark roast).  We usually roast at around 800 degrees F.

We roast 3 - 2 ½ # batches of coffee about once a month in a cylindrical basket. I tried to send a couple little movies but this board wouldn’t accept them. Let me know if you’d like me to send a photo of the basket or bread oven.

The last two photos show the most recent rendition of the coffee roaster.  The stainless steel basket is 5 ½” diameter, 9 ½” length.  I added a frame made of ¼” steel rod so that I don’t have to side bricks into the oven and then try to balance the roaster on those.
A 2 ½ pound batch of coffee fills the basket up to the axle (½ way). Which is good because the beans nearly double in volume as they roast, a little like pop corn.
I got the basket on eBay years ago, it was advertised as a nut roasting basket. I had to make the axle and crank from ¼” square steel that I got locally.

William, the pictures with the tape measure are extremely valuable.  Somehow the unit looks much bigger than it is!  Interesting that the beans swell up that much!

Hi J,

I appreciate all the posts that have been made. I am picking up lots of ideas.  … both what to do as well as what not to do.

Fwiw, I've always appreciated the 'Townsends' perspective on 'the Old Ways', and he's covered this subject, also..



..Have tried this method, myself, and while the 'bowl-bottomed cast iron' is a little better than a skillet, the Ideal way (over a fire) is to either 'seek / encounter' (ie: Farm-sales / Estate-sales / Online, etc) a small 'Drum roaster' (as shown in that vid..) - Or - even Better.. 'DIY one'..

It's actually really Simple to make one, just need some thin-gauge (20-30 ga) stainless 'perforated sheet', ie: Stainless Perfed-Sheet, two #10 metal can-bottoms, some pop-rivets / tool, a long stainless rod / wood closet-rod section (as a handle) and 2x brass electrical 'butt-splices', ie: Brass butt-splicer to keep your assembly all together.

Of course, if you're 'handy with metal-fab' / blacksmith, etc you can do a Much fancier-job on all this, with a hinged-door to add / remove the beans, and more 'proper' ends for the drum and all, but.. It certainly is something 'DIYable' with just a few simple off the shelf parts.

Fwiw..

EDIT: Gaah, I posted this Before 'refreshing' the Page, and did Not see William Haines' Fine posts / handiwork - Outstanding, Good Sir! And yup - Exactly what I was 'pitching', herein.. Great Werk!

At boot camp like four years ago, we discovered someone had gifted a bag of raw beans (25?, 50?lbs) to the base camp. It was open and already a few years old. We found an old air popcorn popper and tried that, but it was obnoxious to run and gave poor results. We ended up running batches using a wok on top of the classroom Rocket Mass Heater. Very satisfying results, but quite a bit of work, mess and time.

For me it has become one of those things I'm glad I know how to do but even gladder I've networked and found a friend nearby with roasting equipment and more knowledge of the field's nuances...

I prefer a heavy stainless steel pan (easier to clean), and an egg whisk for stirring. Oven roasting failed hard.
Just a couple of points to add, because I think everyone else covered the important stuff.
1. If you're crunching the numbers to compare the economics of roasting your own green beans with buying pre-roasted stuff, bear in mind that roasting dries the beans, so they lose weight. Your 1,000g of green beans will probably only get you about 700g of roasted coffee. At least in Japan, it's still totally worth it to buy green and roast at home.
2. When you roast a batch, it's easy to produce multiple levels of roast in one cycle. When I get the beans in my pan to the basic target darkness, I pour about 80% of them into a metal colander to dump heat and sift out the burnt skins. The rest stays in the pan for a few more minutes to get really dark. That way, every time I grind beans, I can blend a mix of roasts that suits what I fancy right then, milder or darker/smokier.
3. Apparently caffeine in the beans isn't very heat-resistant, so the harder you roast the beans, the less caffeine you have left, for better or worse.
That's it.

Matt

Hi Matthew,

Although it is obvious in hindsight, I really like the idea of removing beans at different points in the roast cycle.  

John F Dean wrote:Has anyone successfully roasted green coffee beans in an oven?

I have been roasting coffee beans for over 20 years. I use a bean roaster. I have had several different bean roasters. I am on my 2nd bean roaster from Behmor. It tumbles the beans, very important step in the process. I stove top popcorn maker (I have one as an emergency backup for when TSHTF.) I have been getting all my beans from sweetmarias.com. You can also get a "popper" roaster similar to a popcorn roaster, relatively cheap. I bought one for my son a couple of years ago that also included a starter package of several different kinds of beans. Like some one else said, you are baking the beans, not roasting them.