I was going to talk more about thermocouples and their importance to consistent temperature data in this article, but as I was writing it evolved into more “The philosophy of Ganjing.”And I realized while it’s very important to make people aware and talk about the role of good temperature data, all these numbers, graphs and lines mean nothing unless you are tasting coffee properly and are calibrated to the flavours of a clean roast development.
So, let’s start to break this down, each different coffee roaster is designed quite differently and each gives its own temperature readings according to what thermocouple they are using and where they have been placed around the roasting machine, and each brand and model has their own inherent efficiencies or inefficiencies. It takes an experienced roaster to know this, someone who has used many different brands of roasters understands well that we can achieve the same temperature data from two different brands of roaster, and the flavour development is very different. This is why it becomes so difficult to transfer data from roaster to roaster;the make and design of each different machine has its own particular effect onthe flavour development of the coffee. There are people in the industry who publicly say that only the roasting curve or profile determines the flavour ofthe coffee, but I do not believe this to be true at all.
Each different machine is made from varying grades of metals, they each have different airflow, different barrel speeds,different types of burners, different burner positions, and all give slightly (sometimes acutely) different development of flavours, even if you get exactly the same data on your roasting software. Light roasting certainly lessens the impact of the flavour from each different machine, but it’s when you start to roast darker that the differences really become noticeable. Coffee roasted to 218-220℃ using Cropster profiling software on a Loring Roaster, will taste very different to the same coffee roasted on a Probat or Gieson to the same temperatures and using the same Cropster software.The only people I’ve heard dispute this are people that are somehow connected to roasting machine sales from different companies.
Essentially, it doesn’t really matter which thermocouples you use, where you position them or which software you use. What matters is your understanding of the physics and chemical reactions taking place during the roasting cycle, and how connected you and your pallet are to that process. When you truly understand the concept of a clean development, it’s a dynamic your trying to achieve over all roasters. Once you’re calibrated to the flavour profile of cleanliness, it becomes very difficult to accept any less, and anything not roasted well becomes very easy to identify. “Once you’ve eaten fillet steak, you don’t really want sausages any more.
The concept is a balance of variables that must be controlled to create a clean set of flavour chemistry in the coffee from the balance of physics around and inside the drum while the coffee is roasting. Everything is relative, bean mass/size of barrel, physiology of the bean, air velocity, air temperature, barrel speed, paddles inside the drum (to agitate the beans), the ambient heat throughout the system; all these variables are finely tuned and balanced in different ways in every different brand of roaster according to the companies perception of flavour development. Some have much higher air flow than others, some have burners much closer to the barrel than others, they all use many different types and grades of metal and they allhave different ideas of insulating the drum and heat management, so, this is what makes it important to understand a clean development and how you need to manipulate each different machine to achieve a similar set of physics and in turn, a similar set of flavour chemistry.
This really was the essence of the classesI designed, trying to build a concept of development and clean flavours fromthe roaster. Understanding that we need to develop a profile based on our own flavour memory recognition, not just based on a set of numbers, lines and graphs. It’s this sensibility that the person roasting develops after discovering what a clean roast is, and understanding the physics well enough to create a similar set of chemistry over many different machines, based on a feeling.
I know this sounds a little abstract to people who have learned to roast strictly with profiling software, but itreally is the essence of creating your own flavours and really understanding how your creating them. Most business, companies and home roasters have access to pretty much the same coffees and roasting machines, so it becomes very important to develop this concept to be able to express your coffee in a cleanand unique way.