Coffee Method, pt 1

Kenya Nyeri Gatomboya AB

From time, to time the subject of making coffee comes up and I provide a short description of my method which has evolved as I explore and discover improved methods.  My short explanations have always lacked a bit in detail and justification, so in the interest of time and at the expense of brevity, I am creating a write-up here which I can point to in the future.

The tl;dnr version:

I roast my own green beans, and when I brew, I weigh the beans with a gram precision scale, use a good grinder, use a good kettle with filtered water, and brew with an Aeropress.  Why? Read on.

Here's a video overview on the roasting method.

"You roast your own beans?  Why go to all the trouble?"  

Roasting my beans lets me control the flavor and ensure what I brew is fresh, which makes one of the biggest overall differences in flavor. A store-bought bean may have been roasted several weeks or even months ago--unless it is marked on the package, how does one know when the beans were roasted?  Beans roasted within the last several days have a flavor profile more profound than anything I've ever bought from the store.  It is not unlike the difference between garden vegetables you grow and pick yourself and canned vegetables--practically different vegetables.  There is a potency beyond just nuance in the flavor of freshly roasted beans that, once experienced, is hard to ignore.  I know I tried once, when I let myself run out of beans and bought my favorite store brand of whole, roasted beans.  My tried and true store-bought tasted like some dull imitation of coffee.

A rubber seal keeps beans fresher

I roast beans about every ten days and by some standards, that means I'm pushing the beans a bit beyond their optimum window for freshness, but this is what is convenient for me.  I keep the roasted beans stored in an airtight container and out of sunlight to extend their freshness as long as possible. Even two weeks after roasting, my home-roasted beans are far better than what I find on store shelves.

Freshly roasted bean develops its best flavor about a day after the roast.  However, I am usually roasting the day I run out and find most varieties taste really good even a few minutes after the roast.  During the first 24 hours or so, the beans give off a bit of carbon dioxide, so keep the container unsealed at first to allow this to escape.

Buying Beans

Since I am buying green beans to roast, I have quite a few choices on the origin of the beans.  I have purchased green beans from Amazon, and find them quite good.  However, I have especially enjoyed shopping at Sweet Maria's as they have a continuously changing variety of bean.  Sweet Maria's has cupping scores which I've learned to rely on for anticipating what the bean will be like before I buy.  Additionally, there website is full of great advice, much of which I've incorporated in my method.  Even if you are uncertain about roasting your own beans, you will certainly find their insights on the entire coffee making process worth considering.

Roasting Apparatus

When I first started roasting, I used a air popcorn popper on the recommendation of Sweet Maria's.  This was cheap way to experiment with roasting and Sweet Maria's has a nice write-up on this roasting approach.  After nearly a year and a half, my air popper died.  This was in part, my fault, as I would roast several batches of beans consecutively, each batch being about two days worth of beans.  Each batch would take about four minutes and I would roast enough for at least a week.  When my air popper died, I switched to an oven roast method which I will describe but a lot of what I learned with the air popper still applies.

I like the switch modification made to the popper in this video that shuts off the heating element while allowing the fan to continue to run.  Note they were roasting outside. This is undoubtedly due to the amount of steamy smokiness that roasting creates.  I have a very strong stove hood fan so I found that roasting under the hood with the air popper alleviated most of the smoke problem. I should mention that some stove vents--especially those found in apartments--are only air filters and recirculate the filtered air back into the room.  Because the amount of smoke produced when roasting can be significant, these sorts of stove vents are probably not a good choice to use when roasting.  The porch is a better solution.  Even with my strong fan venting to the outside, the kitchen still smelled of freshly roasted beans for an hour or two.  Some may not find that smell appreciated.  

A colander for holding beans against the vent hood.

Also in the video you can see the chaff floating off the bean and up into the air.  Chaff is a papery skin that is on the outside of the green bean.  It is usually barely noticeable on the green bean, but during the roasting process, the bean expands and this papery skin separates from the bean.

When I roasted under the hood, the fan hood would catch a lot of the chaff on the filter, but even more chaff spilled out onto the stove top. With a sealed glass (induction) stove top, this is very easy to clean up, and a hand-vacuum makes the quickest work of it. The amount of chaff varies with bean variety and some may find the quantity more than they want to deal with inside.  Additionally, not all the chaff will come off all the beans every time.  While the chaff does not seem to be a detriment to coffee flavor, removing the chaff does make for a prettier bean and grind.

To deal with the stuck chaff, and to cool the beans, I found that dumping a cup or so of the beans into a wire mesh strainer or colander and hold the strainer up to the hood vent allowed the beans to cool and the chaff to be sucked up against the hood vent. Cooling the beans quickly with air helps stop the roasting process which is important because the amount of roast, the darkness, has the second biggest impact on the coffee flavor.

Separating chaff and cooling the beans under the stove hood.

What Does Darkness Mean?

Simply stated, the darkness of a roasted bean reflects how much caramelization of sugars in the bean has taken place.  What sugars?  In spite of years of cooking, at first I found it odd to think that there are sugars being in coffee beans.  Before I started roasting my own, the only sugar I was aware of was what I added to make it drinkable.  So what is all this sugar in a bean and why hadn't I noticed?

The sugar in the bean originates as a starch and is converted to sugar in the roasting process.  The entire point of roasting the beans is to convert the starches to sugar and to caramelize those sugars and other compounds to enhance the flavor of the bean.

If you think about caramel candy or toffee's nice medium brown color, this is a direct reflection of how much cooking the sugar has undergone to make the candy.  Most sold coffee beans are far darker than toffee, but if you were to continue cooking the toffee to higher temperatures, it too would eventually become just as dark as any coffee, but you might not enjoy it that much because sugar cooked to that blackness is burnt. Likewise, a coffee roasted to blackness has all its sugars burnt, and burnt beans are commonly sold.  Those shiny, black, oily beans you seen in the fancy grocery "bag your own" bin?  Those are burnt beans.

A great primer on bean roasting levels can be found here at Sweet Maria's website.  I highly recommend a close look, even if you never intend to roast your own beans because it may help you the next time a barista  asks you, "Blonde, medium, or dark"?

Obviously, many people have a taste for the pitch black level of darkness, and I respect that everyone's taste are different, but maybe, like me, you just did not know, and maybe, like me, you'd like to try something different.

Why So Dark?

It piqued my curiosity about why so much coffee is sold so dark.  Some research at Sweet Maria's revealed there is a very good monetary reason for this: uniformity of product.  A bean is made up the many complex compounds reflecting the variety of bean, the growing conditions such as soil type, humidity, sunlight, water, and altitude.  Also, the timeliness of harvest and processing methods are factors that affect the unique flavor of the bean. If you roast a bean to a very light brown, many of the distinct qualities of the of bean are enhanced.  There is a turning point, however, as the roast darkens.

Like an oil distillery obtains different oil by-products at different temperatures, so to, does the coffee bean give off compounds on its way up the temperature scale during roasting.  Where the roast stops determines what compounds are left and what compounds are driven off, and what compounds have undergone changes, such as starches converting to sugar.  Many of the most unique compounds of the bean are present at the lighter roasts, while the hotter temperatures are leaving behind less and less unique molecules, and at the darkest roasts, some compounds, like burnt sugar, are the strongest and dominate.

Take a bunch of beans of varying quality, roast them to the edge of utter burntness, and all the variation or imperfections of the beans are converted to smoke.  What is left behind is a uniformly uninteresting bitter bean that makes a consistently uninteresting $5 drink that can be sweetened and enhanced with sugar, flavorings and whipped cream.  Cheap, low quality beans converted into exactly what a customer expects to find, in every Starbuck's everywhere.  Ka-ching!   In fairness, it isn't just Starbuck's, it is every chain that sells consistency of product as one of its mainstays.

Next time I'll describe my current roasting method using the oven and get into the details of the brew.

[Edited for broken links. --RA]