How To Roast Coffee Beans at Home?

If you have never tried to roast coffee beans at home, then the good news is that it is a great deal easier than you may think. It is also quite a fun thing to do. You may well ask why do we need to roast coffee beans at all? If you click here then you can find out why coffee beans get roasted.

It also depends a lot just how serious you want to take this task. However let's start at the beginning and see what it takes and how much effort you are willing to put in.

Buy Good Quality Coffee Beans

To begin with you will of course need to buy some green coffee beans that can then be roasted. I was quite surprised how difficult that was to do on the High Street. I eventually just bought them online and for my first "experiment," I went with Ethiopian Sidamo and decided to give those a whirl.

They cost around £5 for 400-450 grams (One pound weight)

I had read up about the different ways to do this and discovered that there were a few options;

  • Popcorn Maker also known as a hot air popper
  • Roast the beans in the oven
  • Use an old frying pan

The most common method for roasting green coffee beans is the Hot Air Popcorn Popper method.

The green coffee bean will last for a long time, but when roasted, coffee beans will only stay fresh for about 3 weeks. So never roast more beans than you actually need for the time period.

Understanding the Coffee Bean Roasting Process

Before diving into the methods that can be used, it is more important to understand the process and what is "supposed" to happen. The first time I attempted this I had not really read about the process and ended up with a burnt mess, (think of a mix of charcoal and dirty water) a kitchen full of smoke and a less than happy wife.....you have been warned!!!

Below is the different stages the beans go through. Pay attention to the bean colour.​

Roasting Stage

What to look for?

Beans turn yellow

At this stage the green beans are pretty stubborn but will turn yellow and give off a slight odour of grass

Steaming

After that yellowing, then you should notice steam, which is coming from the water inside the bean

Audible Cracking Sound

First timers be aware..you will hear a crack and it can make you anxious. Worry not that is supposed to happen, and it is the water leaving the bean, and the start of the carmelisation process

Roasted Stage

The beans are now roasted when you hear that noise and are a light roast at this stage- this is often referred to as a "City Roast" and the beans can be used at this stage.

Carmelise

If you leave them they will crack again and get a medium style roast. Many people take them out before that happens as they find that to be a nice roast..it is a matter of checking what you like. (Please note the beans do get slightly larger or puffed up) This is also called a "City Plus Roast" This is my favourite roast as it is a refined and wonderful taste.

Full City Roast

Second Crack

Just before the second crack you get a darker roast, often referred to as a "Full City Roast" and is a big favourite for many people. Now this happens quickly and within a few second this can change to a "Full City Plus Roast" which is similar to what Starbucks use.

This one always makes me jump. It is loud and often the beans will throw off tiny pieces. This is quite a strong roast and too strong for most people. I quite like it though but like everything we all have our own preferences. This is referred to as a "Vienna Roast."

Dark Roast

The sugar starts to burn, you get a lot of smoke and the bean stars to break down. At that stage you have a very dark roast. It is too strong for most people including myself as I find it too strong

When I first did this, I left them in even longer as I really didn't know this was the end of the process. It turned into a mess and yes I did ruin one my wife's precious baking trays along the way. It was impossible to clean and needed to go in the bin. Below I have a video that shows what you should be looking for.

So just be aware from green to first crack is the longer part of the process. After that things happen very quickly. I mean VERY quickly indeed.

Various Home Roasting Methods

Now before you tackle any of these methods I want you to ask yourself two questions?

  • Is it worth the hassle?
  • Are you really sure?

I do not do this any more as it is easier to have professionals, who know what they are doing, give me my perfect roast. That said, it is a whole lot of fun. So if you are still brave enough, or like me silly enough to give this a try, then here are your options.

  • Convection also known as Air Roasting - Popcorn maker or home roasting machine (takes about 4-10 minutes depending on the machine)
  • Conduction - skillet, baking tray or stove top popper (takes about 15-18 minutes)

Option 1 - ​Home Roasting Convection Method

For this method you will need a hot air popcorn maker or a home roaster made for the purpose. I bought the popcorn maker that usually costs around £20 but got it in a sale for £15. The home roasters were just silly money to buy them as they cost around £250-300

Hot Air Popcorn Maker

hot air popcorn maker

Home Roasting Coffee Machine

home roasting coffee machine

The method I will now describe briefly is the Hot Air Popcorn Popper machine. If you want the long and detailed version of this, you can read the popper process in full here. That will include video instructions.

Before beginning the roasting process, set up your popper in a well-ventilated place near a kitchen window or extractor fan. Even better take it outside or into the garage if you have a power source there. Think of a lot of smoke and you will get my meaning.

Turn it on and pour the beans into the chamber. The amount of beans will depend on the size of the chamber, but pour them in slowly until they almost stop moving as that is enough. Put the lid on and put a bowl at the chute to catch the chaff.

In about 3 minutes you will hear the first crack and yes it might scare you. At this stage have a look at them and also smell the aroma. When you are learning this roasting process it is a great idea to examine everything at each stage. I find between 3-4 minutes makes a really good light roast.

From 4-8 minutes things change quickly so be warned. The natural heat inside the beans will continue to roast them even after you take them out. So remove them when they are slightly lighter than you prefer as they will darken afterwards.

When you think they are ready pour them out fast into a metal colander (not a plastic one) and stir them with a wooden spoon. Do this until they are cool enough to touch. That is why I recommend you do this outside as it helps that cooling process. You are basically finished so store them in a jar. Put the lid on to seal them after 12 hours and they can then be stored safely.

Option 2 - Convection Roasting

This option is in my opinion a more fun thing to do.​ If you want to know how to roast coffee beans at home the easy way, then this is the one method that I would recommend.

You also don't need to buy any equipment as most people will have a frying pan or a wok around the home. This is also a super simple process as well. Below you will find a video showing you how to do that.

This process as you can see takes about 7-8 minutes. The main disadvantage with this is trying to get an overall bean roast done. That is why you need to stir and shake a lot. My recommendation is to use this method but do it outside if you happen to have a small stove or a gas barbeque.

Drum Roasting - A Great Option​

Another great way is to use a roasting process known as drum roasting.​ Now you can buy drum roasters but I think they are too expensive. Many people set up their own version of a drum roaster on their BBQ.

There is an example in the video below.​

Other Home Roasting Options

Some people also use nut roasters to do their coffee beans.​ There are a lot of options and many people are quite inventive. Here is a great video that shows most of the roasting options.

So good luck if you decide to try any of these options for coffee roasting at home. You can let me know what worked for you in the comments below (and what didn't work)

Home Coffee Bean Roasting Machines

I do not own one of these though I would love to. I just can not justify the spend as they are not cheap. They cost around £250 for one and although they work great, I just do not drink enough coffee or have a busy enough social life to break out the credit card for one of these.​

home roasting coffee machine

Something like the IMEX-CR model pictured above really is a super job. I have used this one in a friend's coffee shop and it works a treat. Even with this one though he needed an extractor fan to deal with the smoke. This is not a huge commercial one so better suited for the home.

Enda McLarnon
 

Enda McLarnon has a Business Management Honour's Degree and applies his professional insight, to analyse and write helpful product reviews with tips and useful advice. I am also a coffee lover and enjoy tasting all of the coffee types the world has to offer.

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