Home Roasting – Part 1

2010 June 24
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Despite what you may have heard from people in the coffee industry, it is easy to roast coffee at home. The process of roasting coffee is actually quite simple. The basic idea is to take raw, green coffee beans and heat them uniformly with the correct amount of heat input to drive off the moisture and make some chemical reactions occur that also happen to make the color of the bean progressively “browner”. In the earlier days, it was commonly done in a pan over a flame. This tended to scorch the beans, but there are some simple methods that do a respectable job.

Why Roast at Home?

If the idea of roasting your own coffee holds no interest to you, you should continue to buy beans from a respectable roaster. If it does interest you, then there are many good reasons to roast at home. First, just for the fun of it. The process of roasting coffee is enjoyable AND it is a skill that produces a product that can enjoy daily and share with friends. It is much easier than brewing beer and takes much less time. Second, it is allows you to tailor coffee to your exact liking. You will learn which green coffees are your favorites and then roast them in a way that the develops a flavor profile that you like. Third, you control the freshness of your coffee. By roasting in tiny batches, you can ensure that the coffee you drink is at the peak of flavor development on the freshness curve (for instance, you want to wait a few days after roasting for espresso). Lastly, you can save some money. Even though you will pay more for the green coffee than a commercial roaster does (due to repackaging into smaller increments), you will end up with roasted coffee that costs less. The savings varies, but is probably in the 50% range.

Home Roasted vs. Commercially Roasted Coffee

Can home roasted coffee compare with craft roasted coffee from a great commercial roaster? The answer is a qualified “yes” … yes if (1) you are skilled at roasting, (2) you buy fine green coffee, and (3) you have the proper equipment.

When you roast your first few batches, you will be amazed at how simple coffee roasting really is. After roasting a couple of dozen batches, you will realize that you actually know very little about roasting coffee. Assuming you continue and keep working at the craft and have done hundreds of roasts, you will finally understand the roasting process variables quite well. As the great chef, Thomas Keller, says: “you don’t know how to make a croissant until you’ve made 10,000 of them”. Does that mean you shouldn’t start, because it is daunting? The challenge of honing a craft and going through the process of misplaced confidence, disillusionment, and final mastery is good for the soul. There are no shortcuts.

Finding excellent green coffee is a matter of finding a trusted supplier. Good sources include your favorite local roaster, as well as on-line vendors. If buying on-line, look at blogs to see what others say about the quality of the green coffees a purveyor offers.

In the next section, I discuss equipment. Assuming that you have equipment that is capable of roasting properly and has the controls needed for a roastmaster to manipulate variables, you use excellent green coffee, AND you are in the mastery phase of roasting skill, there is no reason that you cannot produce outstanding coffee at home.

What Sort of Equipment is Needed?

I started roasting coffee as a hobbyist in 1987. That hobby lead to a chain of coffeehouses called “The Coffee Plantation” which is the subject of several archived posts on this blog. At that time, the equipment options were very limited. I used a hot air popcorn popper.

A hot air popcorn popper is actually a very cleverly designed (and cheap) fluidized bed roaster. If you use an unmodified one, you have zero controls except an on/off switch and the weight of coffee that you put into the chamber. The weight of coffee you put into the popper is critical to proper roasting. You have to watch the coffee as it starts to tumble in the air when you turn the popper on. If the coffee shoots up, you don’t have enough. If it just kind of sits there and jumps up in “puffs”, it is too heavy. When the beans are uniformly swirling and tumbling, you have found the magic weight for a perfect fluidized bed. Dump the beans out and weigh them. This is the charge weight you will use for future roasts. Start the roaster up and watch the roasting process. Chaff will blow off and out of the roaster and smoke will appear. I suggest roasting outdoors for this reason. In my next post, I will discuss in more detail the roasting process. Suffice it to say that the hot air popcorn popper is your best value in a starting roaster. Some of the better designs can be found on eBay for $30 or less.

There are now on the market many a glorified hot air popcorn popper that include the ability to manipulate more variables. Some have chaff filters, others have cooling cycles, but they all work on the same principle. By the way, there are many commercial fluidized bed roasters, so these popcorn popper variants are in good company. The main difference is that the poppers are basic and electric and the commercial roasters are generally gas fired and have advanced control systems. New hot air roasters for home cost $100 to $200.

Also on the market are home versions of drum roasters. They all use electric heating elements and have some measure of control for airflow and heat. Some have advanced displays and control systems. Most do cooling within the roasting drum, but at least one has a separate cooling tray. Since drum roasters are the industry standard for commercially roasted specialty coffee, a home drum roaster is more likely to produce coffee of a similar quality. The additional controls also enable the home roastmaster to be able to control the roast at a much finer level. Home drum roasters cost $300 to $1,000.

If you have plenty of cash to spare and cost is no object, you can purchase a small roaster (1 lb – 2 lb capacity) made by a commercial roaster manufacturer. These are miniature versions of commercial drum roasters. Plan on shelling out $5,000 for a new one.

What I Bought

I’ve been wanting to roast again to start honing my skill at the craft. Eventually, I will want to build a sample roaster built on the same principle as my larger scale commercial roaster. Not content to wait, I started looking for a roaster that would suit my needs. I went to the best known website for home roasters, Sweet Maria’s, and looked at the various roasters they sell.

I knew that I wanted a drum style so that there would be some element of conduction as a part of the roasting process. I also wanted to have relatively advanced controls and a separate cooling tray. The best choice for my needs seemed to be the HotTop Roaster Basic Model. The reviews indicated that it is robust and can produce some excellent roasts. The roaster has arrived at my home and I will be analyzing it and demonstrating its use in my next post.

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3 Responses
  1. Luke Zeller permalink
    June 26, 2010

    Nice Keller quote. I’m going through Ad Hoc now, and I just gave away Bouchon for Father’s Day.

    I’m looking forward to your next article on home roasting. I thought about buying an old, high-wattage Poppery a few years ago, but never pulled the trigger on it. I’d like to know your thoughts on the kind of quality it can produce.

    • July 1, 2010

      Thanks, Luke. I am thinking about getting a new Presto popper (1440W and about $19) at Walmart and testing it, also. Sweet Maria’s only suggests the poppers with the radial slots and a solid bottom, but I’ve used both. We shall see.

  2. Mark permalink
    June 28, 2010

    Looking forward to reading about your experiences with the new roaster. I’ve had a few, including the smallest commercial model made by Ambex. I figure I’ve ruined about a thousand pounds of coffee, but at least I learned something (I know all the bad tastes produced by poorly roasted coffee).

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