Ways to Roast Green Coffee at Home
Diving into the world of home roasting is incredibly easy. Choose the method you feel most comfortable with from the following:
- Roast in a pan/grill
- Roast in an oven
- Roast in a popcorn popper
- Roast in a purpose-built home coffee roaster
Roasting in a pan or oven is the cheapest way to get fresh beans. But for producing the best possible results we recommend that you choose either a popcorn machine or a purpose-built coffee roaster for their simplicity and consistency.
If you’d like to start roasting on a budget, this video will show you how:
However, the price jump from a popcorn machine to a coffee roasting machine can be massive. Popcorn machines can be picked up brand new from as little as $20, whereas a high-quality home roaster can be around $500, skyrocketing upwards from there. Cheaper machines can be around $150 but are often of inferior quality and may break down sooner.
If you’re serious about roasting your own coffee beans, it’s worthwhile investing your money in a machine that will stand the test of time!
A Word of Caution
- Popcorn machines are designed for popcorn. Using a popcorn machine to roast your coffee will void the warranty, and the machine may break after a few months of regular roasting. Additionally, not all popcorn machines are suited to roasting beans.
- Ensure your popcorn machine heats from the sides. DO NOT roast coffee in a machine that heats from the bottom! This will not only result in a weak and uneven roast, but the collection of chaff can ignite and cause house fires.
- Always clean out all chaff between roasts, and NEVER LEAVE YOUR POPCORN MACHINE UNATTENDED!
Buy a dedicated roaster if it’s within your budget. Your resulting roast is often better than it is from a popcorn machine, and these are purpose built so will usually last far longer than a popcorn machine ever will.
The one method we don’t cover in this guide is microwave roasting. It is possible to roast beans this way, but the poor results and inconsistencies that come with it make it impossible for us to recommend this method. Use one of our four other methods if you’re going to roast at home.
The process is simple, and if you follow our guide, you will be guaranteed a fantastic roast no matter your chosen method.
Understanding the Roxasting Process
In this article, we’ve provided you with step-by-step instructions for each of the four home methods. Your exact approach to roasting will vary depending on your chosen method.
But what never changes is the process:
- Beans get hot
- Beans get roasted
- Beans get cool
- Beans get delicious
It’s a simple process with some necessary steps to note along the way to guarantee great results. These important steps hold true for every method.
Let’s take a quick look at what happens during and after roasting so that you know what’s going on while the magic is happening:
- Temperature: 350F to 500F is the widely accepted temperature range. This varies depending on the method you’re using.
- Agitation: Your beans can never rest and roast! Constant stirring ensures an even distribution of heat, and thus an even roast.
- First Crack: After 3 to 5 minutes the beans will produce an audible crack. This crack indicates that your beans are lightly roasted and ideal for white coffee. This the minimum amount of time required to produce roasted beans. Continue roasting and agitating for darker roasts.
- Second Crack: After a few more minutes another crack is heard. This crack indicates a medium roast. A few more minutes of roasting and your beans will be burnt and unusable. Experiment with times to find your favorite roast.
- Tip: We usually wait roughly 30 seconds after hearing the second crack.
Cool Down: Transfer beans to a metal colander or baking paper to cool. Use two metal colanders (plastic can melt). Shake and transfer your roasted beans between colanders. This cools the beans quickly and removes the chaff.
Spread evenly over baking paper to substitute for a metal colander. This method is not as effective.
- Remove Chaff: Chaff is the dried husk of the coffee bean. It is very messy. Cool your beans down outside or in the sink to reduce clean-up
It is one of those things that you’ll get the feel (and eye) for with practice. This video is a good start:
Post-Roast and Chemistry
When you’re roasting coffee beans, you are creating an awesome chemical transformation – the Maillard reaction.
Over 800 compounds are transformed from the boring, flavorless compounds present in the raw beans into the delectably delicious and aromatic compounds found in roasted beans.
In the very early stages of roasting colored plant compounds such as chlorophyll, anthocyanins, etc begin to decompose […] accompanied with subtle changes in aroma from grassy to more toast/popcorn notes.
This is why raw beans smell and taste nothing like roasted beans. The compounds in the beans are waiting to be transformed!
Roasted beans release gas (CO2): This continues for weeks after roasting. Why should you care?
- CO2 helps to naturally preserve roasted beans by displacing oxygen
- Oxidation ruins beans. They become stale
- Too much CO2 in coffee beans creates too much crema (a bad thing)
- Not enough CO2 creates stale tasting coffee (also a bad thing)
De-Gas: Wait 12 hours before sealing in a container (Allow the initial Co2 to escape)
- Sealing newly roasted beans in storage too early will lead to CO2 pressurization. This can pop the top off your container, potentially damaging it.
- Coffee beans that contain too much CO2 will result in an undesirable flavor. Give your beans a chance to de-gas!
- Opinions differ. From a few hours to a few days. In our experience, we’ve found 12 hours to be a good rule of thumb. Your experience might prove otherwise – do what works for you
Grinding and Storing after Roasting
- Wait 24 Hours before you Grind & Brew. Beans need a day to mature and reach full-bodied flavor
- Store in airtight container: Keep beans fresh and use within seven days
- Coffee is always best when it’s fresh. After more than one week, your roasted beans will begin to turn stale as oxidation does its thing
All right – enough with the science side of things, you’re here to learn how to roast your own beans at home, so follow these steps and you’ll be roasting like a pro in no time…
1. Buy Green Beans
It all starts with the beans, which technically speaking are seeds. Fresh beans are green. Once dried, they become several shades lighter. Once roasted they are completely transformed, becoming the beautiful and inviting rich shades of brown that we’re used to seeing.
Excellent coffee is all about consistency. Choose beans that are uniform in size and color: this ensures an even, consistent roast and flavor. Getting these two elements correct – color and size – is vital to avoid producing coffee with an inconsistent and unfavorable flavor
When coffee is roasted consistently, baristas and other consumers know what they’re dealing with and can trust they’ll get the same cup every time.
This is where the magic happens. Choose from one of the following four methods and follow our guide to producing the freshest, most delicious beans you’ve ever tasted!
We’ll show you how to roast with a pan, an oven, a popcorn maker and a home roaster below.
Roasting Beans in a Grill or Pan
You’ll find plenty of how-to videos on YouTube, however, be wary of who you take advice from – many DIY roasters tend to overcook their beans using this method!
Do not use a coated/non-stick pan. Doing so will negatively impact the flavor.