Next year marks my twentieth year roasting coffee and it is not an exaggeration to say I have wanted to open my own roastery since the very first time I fired up a roaster.
This year that wish came true with the opening of the new roastery on Blackwater Road Dublin Industrial Estate.
A critical decision was of course selecting which type of roaster to use. I am more than happy with the roasting system, drum & software on the new machine. Here’s a couple of reasons why.
A state of the art machine with a thermodynamic drum “this is the most advanced drum in today’s industry. Built from two layers of mild steel with a middle layer of pure copper, it has extremely high thermal absorption and conduction characteristics. In contrast to standard drums, in which roasting is performed by direct, limited contact between the beans and the drum, the Ghibli Thermodynamic Drum displays a unique method of refined conduction applied to a wider contact surface between beans and drum. Heat is generated via a copper layer creating a 1.4mm gap between the heat and the beans, removing any risk of burn marks. This drum excels in producing an evenly-roasted batch of superb beans.”
Conduction Vs Convection
Heat conduction or thermal conduction is “the transfer of internal energy by microscopic diffusion and collisions of particles or quasi particles within a body due to a temperature gradient.”
As opposed to convection which is defined as “the concerted, collective movement of groups or aggregates of molecules within fluids (e.g., liquids, gases) and rheids, through advection or through diffusion or as a combination of both of them.”
An example of convection heating is to heat a metal rod at one end. The heat travels from one end of the rod to the other through high speed particles colliding with slower ones.
An example of convection is to put a heat source in water, heated fluid is caused to move away from the heat of the source.
This in my opinion is why the Ghibli stands head and shoulders above other roasters (in this price range). A high level of conductive heat particularly early in the roast produces a rich cup with caramelisation of sugars and fats. This is because the first two thirds of the roasting period are endothermic meaning the beans absorb energy this is crucial for inner bean development. Once this has been established the final stages of the roast can be achieved through convection a higher airflow or quicker drum speed . Coupled with a unique roasting software which allows us to predefine and program personal roast profiles. By recording the desired heating curves, endless roast profiles can be applied, again and again with the greatest accuracy.
Learning to use the roaster has been a lot of fun, hopefully you’ll see the results in the cup!
This is my first blog post on the new website I hope you like the look and feel to it. There has been some really positive uptake on the “coffee club” subscribtion service which is really pleasing.