Home Coffee Roasting on Flickr

This guy created a flickr photoset that outlines his home coffee roasting method:
http://flickr.com/photos/mezzoblue/sets ... 104267809/

I don't drink that much coffee, so I barely even brew at home, but I think the flickr photoset "how to" format is kinda cool. It allows for commenting on each step individually, which is handy.

Best,
Michael

I've been roasting coffee beans at home for a few years now and thought this would be a good time to write a little bit about my experiences.

First, why would you want to bother roasting your own coffee beans? I mean, who does that? Well, in the pre-industrial days, most people who drank coffee either roasted it at home or bought it at small, local coffee shops that roasted beans. The mass production of pre-roasted coffee is an invention of the 19th century. Home roasting faded away and by the mid-20th century most coffee was sold pre-ground in large cans that were later repurposed to hold screws, nails, and whatever else dads needed to keep organized in the basement.

Specialty coffees made a comeback in the 1960s, with local shops roasting high quality beans in small batches. I lived a few blocks from the original Peet's, founded in 1966 in Berkeley, and have a soft spot for them. Roasting beans at home remained about as popular in the United States as making your own salumi or pickling ramps. As many of us rediscovered the pleasures of recreating so-called old world techniques and cooking more by hand, home coffee roasting revived.

Other than nostalgia, why do it? The most important reason is that you get much better, fresher coffee. Most freshly roasted beans are at their best the day after they are roasted. (Some types of beans benefit from a two-four day rest.) They begin to go downhill after that. You can certainly extend their life by storing them in an airtight container with a one-way valve to let out CO2. But once the roasted beans are exposed to air, the clock starts ticking. Within a week or two, even beans that would have once produced great coffee now produce a much less intersting and aromatic cup. That's why most packages of coffee say to buy in small quantities that you can use up in a week. When you roast at home, you are drinking coffee from extremely fresh beans all the time.

Roasting at home is cooking. Just as you'd vary how you cook a chicken at home, you can vary how you roast beans to produce different flavor profiles. Coffee can be woodsy, floral, fruity, malty, toasty, acidic, chocolaty, smokey, and carmely. But not all at once. What you smell and taste in the cup is determined by many factors, including the beans you start with, how they are roasted, how you make the coffee, and what temperature you drink the coffee. When roasting, the most important variable at your control is the roast level. Lighter roasts produce brighter, more acidic coffees that will better reflect the characteristics of the bean's origin. Darker roasts will produce coffees that taste of caramelized sugars and will have more body, at the cost of less nuance of the bean's origin showing through. You have other levers to control also: beans that are brought up to a particular roast level more slowly will taste different from beans roasted quickly. Home roasting allows you to experiment with all of this.

To give you a sense of what I mean, consider this description of Sweet Maria's Sidama Deri Kochoha from Ethiopia:

Deri Kochoha has a strong floral character that remains prevalent all the way from the ground coffee to the cup. The dry fragrance has strong scents of honey and molasses-ginger cookie, with soft floral hints of lilac and star jasmine. A smell of ripe fruit is also prevalent in its representation of peak sweetness. Adding hot water brings up spiced tea, like bergamot, in the steam. Wafts of fresh cup flowers come up off the breaking crust along with a note of lemon verbena. Deri Kochoha's cup profile is so pristine, and with a delicate, but balanced sweetness and acidity. There is a refined sweetness of simple syrup at lighter roast levels, along with hints of toffee and butterscotch candy. The acidity is brilliant has a quality of lemon tea. This coffee is floral, to say the least, and this defining characteristic will hold up in more developed roasts as well. Full City roasts highlight the fruit complexity that this coffee is capable of producing. Pineapple, plum, mango, red apple, tamarind - the list goes on and on becomes more perceptible as the cup drops in temperature. This Sidama has great body and amazing mouthfeel, and will make an amazing single origin (SO) espresso. Lots of chocolate with bracing, citrus acidity - like a dark chocolate orange. This is a very versatile coffee that does extremely well in all applications.

Those beans are $6.75 per pound. And that's the kicker: home roasting is actually less expensive than buying good beans from a local roaster. I buy my beans from Sweet Maria's and pay in the neighborhood of $6 per pound for exceptionally high quality beans. Roasted beans from Intelligentsia, Metropolis, or other high-quality local roasters are at least $15 per pound and usually more. Ah, but the roasting equipment! That can be had for about $20. I'll get to that in a minute.

I usually order about 10 pounds of green (i.e. unroasted) beans at a time - usually about 2 pounds each of five different varietals. The green beans last quite a while, but I usually just buy enough for 2-3 months. Here are the green beans:




You don't need fancy equipment to roast beans. In the pre-industrial days, the most common method to roast at home was to put the beans in a pan over fire. Today, the easiest way to get started is to use a cheap hot air popcorn popper, like this one:



There's a thriving market for out-of-production, vintage hot air popcorn poppers that hard-core enthusiasts prefer to the newer models. (Note that you can't use all types of popcorn poppers to roast beans. Search on-line and you'll find discussions of the most common ones. Also note that roasting beans will void the warranty and could possibly start a fire. Once you roast beans in the popper, you'll have some residue in there and won't be able to use it for making popcorn. But, hey, these things are $20 new; $2 at a garage sale, flea market, or thrift store.)

Roasting in a hot air popcorn popper is simple: load about a 1/2 cup of beans into the hopper and turn it on. The beans will start to spin and, as they roast, they will throw off chaff (an outer layer of papery skin that comes off the beans). This chaff has a way of flying all over the kitchen, so I put a bowl lined with a moistened paper towel under the spout of the popper. You may also see a little smoke coming out of the popper. This is normal, but you also have to use your judgement to figure out whether you've overheated the machine.

After a few minutes, the beans will be noticeably darker and eventually you'll hear a cracking sound. This is called "first crack," the beans will be around 400 degrees. You could stop the roast here and get a really light roast. Probably too light for most people's taste. Continue roasting and you'll have what's called a "city roast", or a medium roast. Eventually the cracking sound will stop, but the cooking will continue. When the beans are at your desired roast level, turn the machine off and dump the beans onto a sheet pan or bowl to cool them. Once cool, store them and let rest for at least a day before using.

The hot air popcorn popper produces really nice coffee. The drawbacks are, first, you can only roast about a 1/2 cup of beans at a time; i.e. about a days worth for my wife and me. So you have to roast often. Second, you don't have as much control over the process as you would with better machines. Finally, the heating element in a popcorn popper cycles on and off, keeping the temperature below some specific level. In my unit, this meant I couldn't get a really dark roast - that was generally fine for me, since I don't like really dark roasted coffee. But it also meant I couldn't roast beans for espresso. Many people hack into their popcorn poppers to disable to thermometer. Here is a nice page from Sweet Maria's on roasting with a hot air popper. This is a very easy, inexpensive way to get started roasting beans at home.

Perhaps with an eye towards preemptively steering me away from hacking into the popcorn popper, my lovely wife surprised me one day with a Behmor coffee roaster:



This looks like a toaster oven and it's about as easy to use as one. You load the green beans into the metal hopper, which fits into the roaster. Attach another piece that catches the chaff. Close the door and set the controls for the length and type of roast you want to use. This roaster produces no smoke or heat and catches all of the chuff. It can accommodate up to a pound of beans at a time, though I usually only roast a half-pound since I like to experiment with the settings. As the beans roast, you'll hear the first crack and, depending on how long you roast, you'll hear what's called the "second crack". These sound a little different - more like Rice Krispies in milk. At this point the beans will be quite dark, what's called Full City or Viennese roast. Go a little longer and you'll have French roast and then Italian roast. However, you have to be careful because the bean can go from dark roast to charred and smoky quite quickly.

Each type of bean roasts at slightly different rate. So one batch of beans may reach "City+" after 10 minutes; another may take 11. Although the Behmor program that you set will switch from roasting to cooling after a pre-set period of time, it is better to monitor the beans yourself and manually switch to cooling mode yourself. The machine cools the beans and then you take them out:



I end up roasting about twice a week. It takes me about 15 minutes to measure out and roast the beans and then another 10 minutes or so to cool them. My only active time during the roasting process is switching from roasting to cooling - and you really have to pay attention to the process here. You need to know when first crack starts so that you can properly assess when the batch will be done. But, for most of the 25 minutes, I can do other things, like actually brew that day's coffee, unload the dishwasher, etc. In short, roasting places very little demand on my time.

Sources:
Sweet Maria's is my favorite reference for buying beans and equipment, and for learning about roasting and brewing.

Home Coffee Roasting by Kenneth Davids is a classic book on roasting, originally written before home roasting surged in popularity and now revised and update. My short history of roasting at the beginning of this post is from material in this book.

There are also a lot of good discussion forums for home roasting, including Sweet Maria's, Coffee Geek, Home Barista, Homeroasters.org, etc.

Huzzah! We've been roasting for almost 5 years as well. I got Mr.pairs4life a Nesco from Sweet Maria's. Today, I roasted 3 batches of green beans in it. I ordered the beans last month and decided we should "cup" from each one so I don't end up missing out on something extraordinary like the Columbia San Antonio Lot #230. It was so gorgeous, I drank it black. I've never found a coffee that I could do that and find the beverage enjoyable.

This is great, and I'm going to try it. I've just gone to check that I still have a 1970's popcorn popper, and I do.

Here's a quote from Lame Deer, Seeker of Visions, the setting is the Pine Ridge Reservation in the 1920's:

...Grandma always got up early in the morning before everybody else, taking down the big tin container with the Government-issue coffee. First I would hear her roasting the beans in a frying pan, then I would hear her grind them. She always made a huge pot holding two gallons of water, put in two big handfuls of coffee, and boiled it. She would add some sweetener--molasses or maple syrup; we didn't like sugar. We used no milk or cream in our pejuta sapa--our black medicine.

For anyone who might be interested, snap and I conducted a little coffee experiment. We stored beans for a month three different ways. 1) Whole beans in the bag 2) Whole beans in an air tight container 3) Pre-ground beans in a bag

To my surprise the air tight storage yielded the worst results. The beans had lost all their character. The coffee tasted thin and bitter. As I understand it, roasted coffee beans emit carbon dioxide which impacts the beans more than oxygen.

The pre-ground beans were actually passable. The coffee had lost a lot of flavor, but there was still some subtlety. There was a hint of metallic bitterness on the finish which I suspect is from oxidation.

The beans stored in the bag still made pretty good coffee. Certainly fresher beans yield a more complex and rounded flavor, but the month old beans made some tasty coffee nonetheless.

So I guess the conventional wisdom holds true. Store whole beans in a dark environment with as little air as possible while allowing the carbon dioxide to escape. And brew your coffee as close to when they are roasted as possible.

Cool experiment. When you say "whole beans in the bag," was this an air tight valve that allows CO2 to escape? Or a fully air tight bag?

I store my coffee in a tin that has a valve that allows CO2 to escape, but is otherwise air tight (except when you open the lid!). See http://www.sweetmarias.com/sweetmarias/ ... valve.html. I find that a regular air tight jar is perfectly fine if you use up the beans within a week, especially if you aren't roasting your own beans. If you roast, though, a lot of CO2 comes out in the first day or two, which is why I like the tin with a valve.

It was the bag the beans came in which has a one way valve for co2 to escape. The bag was not sealed.