Coffee Roasting at Home

Roasting coffee at home is great way to have fresh, high end coffee more affordably. It’s easier than you think and it also allows for experimentation, so you can learn what roasts and flavor profiles you enjoy most.

One of the things I decided to do with my time during the pandemic is learn more about certain categories of foods and drinks that I didn’t feel confident in. One of those areas for me is coffee. All I knew about coffee was that I liked the pricey single origin coffee that I got from local roasters and that I really didn’t like the coffee that’s available at the grocery store. So I decided to read Blue Bottle Craft of Coffee, a book about the creation of a global coffee company.

The book covers a wide range of topics regarding coffee: its origins, how it’s grown and harvested, how it’s imported, how to roast it, and how to brew it. For roasting coffee at home, the author recommends using a perforated baking sheet to roast the coffee beans in the oven. I tried this method but I didn’t like how to coffee turned out and I especially didn’t like having the oven opened and closed throughout the process, which made my 470 sq. ft. apartment feel like an oven.

This led me to trying other roasting methods, taking notes of how the coffee turned out, and the ease of roasting the beans. You can read about all types of home roasting methods here. I’ll show you the method that works best for me.

A WARNING FOR PERFECTIONISTS

Home roasted coffee won’t ever turn out perfect. And that’s okay. There will be slight differences in roast level between coffee beans which will actually add more depth of flavors to a cup of coffee. So don’t stress over it!

Equipment

Whirley Pop Popcorn Maker

Not only does the Whirley Pop popcorn maker roast coffee wonderfully, it also makes kettle corn almost as good as the stuff you get at the farmer’s market. It’s been one of my favorite purchases as of late. There is some debate of whether the more expensive stainless steel Whirley Pop with metal gears is better than the original with nylon gears. I have the cheaper, original Whirley Pop and it has performed well so far.

A Pair of Strainers or Colanders

These will be used to cool the beans and remove the chaff that comes off during roasting.

A Stopwatch

This will be used to track the progress of the roasting to ensure it’s happening at the correct pace.

Ingredients

Sweet Maria’s is a great place to buy green coffee beans. They sell a 4lb. sampler set for just under $30 after shipping. My neighborhood roaster sells 1lb. of coffee beans for nearly $20, so it’s quite the steal. All of the coffee beans they sell include a full stat sheet of facts including the coffee’s origin, flavor profiles, and roast level recommendations.

I would also encourage you to check if any of your local coffee roasters sell green coffee beans to support local businesses.

When I roast coffee, I try to make only enough to last me a week. I brew pour over everyday using 25g of coffee, so I’m aiming for a roasted coffee weight of 175g. The beans will lose about 10 to 15 percent of their weight from water loss when roasted, which means I’ll need to roast a batch of 200g of green beans to yield somewhere between 170g and 180g of roasted coffee.

175g of roasted beans

Roasting Process

Before I start describing my roasting method, let’s first get on the same page with some roasting terms.

First Crack: An endothermic reaction within the coffee bean noted for sounding like twigs snapping or popcorn popping.

Second Crack: An exothermic reaction that results in another audible cracking sound and the coffee beans releasing their oils.

Image via Sweet Maria’s

Since I’m not using a thermometer in this method, using a chart to visualize roast levels will be helpful. In the chart above, First Crack begins on #7 and continues through #9 and #12 denotes the beginning of the Second Crack.

I’ll be aiming for #11. This will be a nice medium roast, that is dark enough to bring out the the deeper, more complex flavors of the coffee to give it body, while maintaining the sharpness of the fruitier notes. If I hear the Second Crack, I’ll know I’ve gone too far and end the roasting process.

You can read more about this chart and specifics about roast levels in this guide, Using Sight to Determine Degree of Roast.

Instructions

1. Preheat the Whirley Pot

Preheat the pot over medium heat. It’s ready to go once you stick your hand in the pot the air is just hot enough to make your hand start sweating and feeling uncomfortable.

2. Start Roasting

Add the beans to the pot, close the lid, start the stopwatch, and begin cranking at a moderate pace. This is a marathon, not a sprint. As the roasting begins, you should notice the coffee smelling like hay.

3. Listen for the First Crack

Around 6 to 8 minutes, you should start noticing steam and smoke coming off the beans. The beans will begin to smell like bitter dark chocolate. The First Cracks should be distinct in sound.

4. Use Sight and Smell to Judge Doneness

After the first crack, the roasting process begins speeding up. Pay attention to how the coffee smells. Does it smell like it is scorching? Or does it smell like sugar caramelizing? Open the lid and notice the color of the beans as they darken. The beans should be ready when your stopwatch shows 10 minutes, but use your judgement and remove the pot from the heat when you feel like it.

5. Begin the Cool Down Process

This cooling process serves two missions: to cool the coffee and to remove the chaff. Transfer the beans to a metal colander. Pour the beans back and forth between the colanders. The more air time the beans get between the colanders, the quicker they’ll cool down and the more chaff will float out. It’s good to do this over the sink to contain the mess or even better outside, where a cooler temperature and a breeze can significantly expedite the process. The beans are sufficiently cooled when they can be comfortably handled with bare hands.

6. Weigh the Roasted Beans

A good practice to get in the habit of when roasting coffee is to weigh the final product to know how much water was lost during the process.

7. Store the Coffee Beans

Store the beans in a container without a lid for 12 hours so they can off-gas and release CO2. After the 12 hours, store the beans in an airtight container in a cool, dry place.

8. Brew the Coffee

Using whichever method you prefer, brew your coffee. Taste the difference of freshly roasted coffee and hope you never have to go back to anything else.

Roasted coffee before chaff removal
Cooling down, getting some air time


Please don’t tell anyone, but this is one of my most played songs on Spotify.

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