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How to Roast Green Beans at Home

Coffee Roasting

Green coffee beans have been much talked about in recent years, thanks to their reported fat burning properties. As all coffee lovers know, however, these ‘magical beans’ are nothing new; they are the essential base for all coffee drinks.

While coffee beans are often described as being dark brown in colour, this description refers to the roasted beans which are sold in coffee shops, used in grinders and on display in roasteries. But the humble bean starts life as the seed of a coffee plant cherry, and when this seed is removed from the cherry, it is naturally green. It only takes on the glossy brown colour once it has been dried and roasted, ready for grinding. It is in this form that most people buy their beans.

However, there is another, more exciting, more affordable way to get your morning cup of java, and that’s home roasting.

Roasting your own beans will transform them from their original green colour to a lovely shade of brown, while giving you complete control over the flavour. Yes, there may be a bit of experimentation involved to start with, but it’s a fun, satisfying experience that can become quite addictive as you experiment with different beans. Plus, whenever you have visitors, it’s very impressive to say you roasted the coffee yourself!

Methods

One of the beautiful things about roasting coffee beans is that it can be done using equipment that you already have in your kitchen, meaning there is no need to go to great expense to get great tasting, freshly roasted beans. Here, we give you a guide to the most popular methods.

Before you start any of these processes, choose a well-ventilated area, ideally outside, or near open windows and extractor fans, as roasting will generate a lot of smoke!

Also remember that you will need to leave the beans for 12 hours to de-gas after roasting so that all the Co2 escapes. Only then are they ready for grinding.

Frying Pan or Skillet

The frying pan is a great starting point for roasting beans, as it is highly likely you already have a pan at home. This process works best with a heavy cast iron or steel pan, and gas stove.

Note that you should never use a non-stick pan as these have a coating on their surface, which can affect the flavour of your beans during roasting. For the same reason, it will be best if you have one pan that you use only for coffee, otherwise the flavours from previously cooked dishes will transfer to your beans. Bacon infused coffee may not be so great...

How to roast coffee with a frying pan:

  • Heat your pan to 230°C
  • Pour a small amount of beans into the pan, so they all have direct contact with the surface
  • Now, stir, stir and stir some more to ensure the beans do not sit still
  • After 4 or 5 minutes you will hear a crack from the beans, which indicates that they are at a light roast stage. A second crack at around 6 or 7 minutes is the sign of a medium roast. At this point, remove the beans from the heat to avoid burning.
  • Immediately pop the beans into a colander and shake them to cool down.

PROS

Very convenient
Affordable

CONS

Getting the perfect temperature and timing is tricky

Popcorn Maker

This might sound unusual, but you can safely roast coffee beans in a popcorn maker. There is a caveat though, the machine must have a side vent, otherwise the beans will burn and not rotate.

How to roast coffee with a popcorn maker:

  • Pre-heat the popcorn maker
  • Drop half a cup of beans into the machine
  • Use a wooden spoon to encourage consistent movement (agitation) amongst all the beans, and when this is achieved, put the lid on
  • Listen for the first crack at around 4-5 minutes which indicates light roast, or wait for the second crack at around 7 minutes for a medium roast.
  • Remove the beans
  • Place the beans in a colander to cool
  • To help avoid a lengthy clean up, we also recommend putting a bowl near the spout of the popcorn maker as the roasting will generate a lot of chaff (dried husk from the bean), which is messy.

PROS

Simple and quick
Rotation is done for you

CONS


May put too much stress on the machine and cause it to break

Home Coffee Roasting Machine

If you are planning to become a serious roaster, then you may have decided to invest in a home coffee roasting machine. These should give you more consistent results than the other options.

The process involved in a home roasting machine is very straightforward and will be largely determined by the manufacturer’s instructions. However, the general guidelines are:

  • Ensure the machine is switched on
  • Add the recommended amount of beans
  • Watch the roasting and agitation process, listening for the cracks – the first crack is lightly roasted, the second will be medium
  • Once your desired roasting is achieved, turn off the machine and allow the beans to cool, either in the machine or in a colander, depending on the design

PROS

Designed for this purpose
Less mess and easy to clean
Consistent results

CONS

Can be expensive

Wood Fired Oven

If you have a wood fired oven, this can be used to roast coffee beans, thanks to the ventilation and high levels of heat these ovens can achieve. You will, however, need a roasting container. These can be purchased or built with heat-resistant material. They need to resemble some form of mesh cage that is round or cylindrical with a long handle, so you can rotate it easily to maintain even heat distribution.

How to roast coffee with a wood fired oven:

  • Heat the oven to around 250°C or higher
  • Place a small amount of beans in the roasting container
  • Put the roaster in the oven and continuously roll it back and forth, moving the beans
  • Continue to do this until you hear the cracking which indicates roasting has occurred
  • Place the beans in a colander or on a tray and toss them or spray with cold water to stop the roasting

PROS

Wood smoking will add to the aroma of the beans
Roasting container is affordable

CONS

Quite exhausting to manually move the roasting container continuously

Summary

Roasting coffee beans at home can be a fun experience, and while it will require a bit of trial and error at the beginning, it is well worth it from both a cost and flavour perspective. Once you have successfully made your first batch of freshly roasted coffee, there will be no going back. With coffee made exactly to your specifications, in a budget friendly way, it’s a great way to explore the wonderful world of coffee.