Written by Matt Winton

When I first heard about this small sized, electric, sample / home roaster, I have to admit; it peaked my interest. Many professionals were talking about it. Mainly about the versatility for manual control in the roasting process.

Being very new to roasting myself, I was very curious.

I continued to learn on a larger, traditional gas roaster, and was figuring out the effects of energy, airflow, time and temperature on this large roaster, and began to understand more. I had heard that similar results could be achieved using ROEST, but was unsure if the same principles from the large roaster would apply.

Locked down with ROEST

When coronavirus hit, I was fortunate enough to have my ROEST machine with me at home, along with a small supply of different green coffee samples. I began to roast and test. I quickly discovered that when using the Power profiles, I could replicate the effects of the Gas coffee roaster very similarly. Applying energy or airflow at different points in the curve brought the expected results. I was so pleased to see that what I had learnt was not just applicable to one (production) roasting machine! The versatility of the ROEST sample roaster at home meant that I could roast 50-100 g of coffee without a problem, in the comfort of my own living room, and then brew these samples for my prospective competition at my leisure.

“ Once I worked out what each function corresponded to in the cup, I found it a lot easier to develop roasts with purpose. ”

*Matt enjoyed the cozy atmosphere of home roasting during the lock-down.*

understanding the parameters

The functionality and diversity of the parameters in the ROEST meant that I could really dive deep and I had a steep learning curve. Once I worked out what each function corresponded to in the cup, I found it a lot easier to develop roasts with purpose. This first month (April 2020) or so was a journey of learning, discovering how the total roast time affected vibrancy of the coffee, controlled by how the Power affected total roast time, airflow affected power, drop/charge temperature affected roast degree… There were so many variables!

The best thing I did was roast a lot of the same coffee, with slightly changing profiles, adjusting only one variable at a time, and cupping afterwards. This meant that I could see what did what in each roast.

Matt’s Roasting Approach

My approach to roasting is quite simple, I don’t try to do many changes to power or airflow during the roast, and I try to apply as much energy in a shorter amount of time as possible, without overdoing it, in order to create bright flavour, acidity, sweetness, and mouthfeel. This is a very general approach, and is actually coffee specific, but if I could roast a coffee with no changes to settings, I would try that. So, I do only Power Profiles, and manipulate the roast time and temperature with the Power setting.

Early on, I decided to couple the airflow with power, to “mimic” a Loring style of roast, where more energy was applied through hot air (not totally accurate, but for this explanation, close enough). For example, this profile uses 80 % airflow + 80 % power, then after 1 minute 70 % airflow, with 70 % power for the rest of the curve. (From here out I’ll just refer to “Power”, when I mean both Power and Fan.)

Roasting time

Firstly, I played with the overall power setting, and saw how this controlled total roast time particularly. I found that any roasts longer than ~5:30 would tend to be a bit flat, and not very vibrant. I found that roasts shorter than ~4:30 were a bit too acidic, and sharp in general. So, I had a rough guide for how long I wanted my roasts now. I knew I wanted to get as much energy into the beans at the start of the roast, but if my power was too high, the roast would be too short. I developed a profile that had high power for the first minute, then dropped by 10 %. This gave me a profile that lasted for 5 minutes, and I could adapt, whether I needed more or less energy for different coffees, at different points in the roast.

charge temperature

The next step was to figure out what charge/drop temperature to hit. This temperature dictated how quickly my roast picked up (affecting total roast time), and also initial energy application. I found that temperatures too low were resulting in longer roasts (tasted flat) and too high temperatures ended up getting too hot before having proper development. I settled on 210 °C for a 100 g roast, and 190 °C for 50 g roasts, through trial and error. These temperatures were a good balance between getting enough initial energy, and not burning.

DRUM RPM

The drum RPM was an interesting one, it was a totally different variable than I was used to, and as such, I didn’t play too much with it. I tried a few curves with lower, and higher than 55 RPM, and found that they just tasted bad. Perhaps there’s something to changing the RPM throughout the roast, but I haven’t tried it too much. 55 RPM was giving great results, so I stuck with it.

DEVELOPMENT TIME

Generally, I would be doing 30-45 seconds of Development time after first crack for any coffees. I found that more got too hot, and I would get lots of roasty notes, and anything less was a little too light, and perhaps a little green for my taste. This is, of course, only applicable to my roast profile, as I have a certain rate of rise which dictates my DVT.

Roasting graph of Matt’s profile. Matt is one of our Beta Users for new User Portal - soon all our ROEST users will be updated with this latest version.

Copy the profile for your ROEST library here (Switch the setting to Power profile and set on your machine the correct charge temperature).

SUMMARY

This is how I came up with the curve I used for all my 100 g roasts. This profile needed to be slightly adapted for different coffees, depending on the varietal (bean size), process (density), and altitude (density again).

For example: I found that a High Altitude Washed Pink Bourbon from Colombia required a boost of energy before first crack, in order to bring out extra vibrancy in this coffee, otherwise the curve after FC would stall. And if I applied that curve with extra energy to a heavily Fermented Natural Pacamara, it would be burnt at first crack, and the curve would run away, and get way too hot.

I discovered that with this total roast time, I had coffees ageing in a similar way to the bigger gas roasters (but slightly faster). The coffees tasted great up to 24 hours after roast, then dropped in intensity, becoming quite shy. They then slowly picked up more flavour and vibrancy, degassing better after 7 days, up to 14 days, then anything after 21 days was starting to lose quite a bit of intensity and sweetness.

Learn more about the parameters on our How to ROEST page here.

…AND THE MAINTENANCE?

Cleaning and setting up this machine is so, so easy! I wipe down the collection tray, empty the chaff collector, and pack up the ventilation hose in less than 5 minutes after cooling down!

The first 3 months were such a learning process, and I am very grateful for having the free time to test the parameters, and come up with a roast profile that I liked. I hope that by sharing my journey, you could have a place to start, and test it for yourself. Perhaps your taste preferences ask for a longer roast time, or a shorter one. It’s up to you to test and adjust and have fun learning!

-- Matt.

Photo credit: Anja Christina

Interested in another tip on how to create 50 g roasting profile? Read more about it in this article.

Developing roast profile with Matt Winton