Crafting Consistency | Our Journey from Vintage to Visionary Roasting

I was very fortunate to learn to roast coffee, starting back in 2013, on a beautiful 1942 Probat UG15. It was beautifully restored and pretty much original, with the exception of being modified by Mark to add a separate motor with variable speed controller for the drum.

As I learnt more about coffee, and about my role in coffee's journey from bean to cup, I realized that the most important thing to strive towards is consistency.

Without mastering consistency, all other efforts to manipulate flavour are futile.

Then began a journey of around six or seven years where we really tried to push the limits of our 70-odd year old machine. between 2014 and 2016 we took meticulous hand written notes, with stopwatch, analog gauges and calculator, of every single roast we did (around 4000 batches!) finally making the leap in 2017 to thermocouples, a digital gas pressure transmitter, and Cropster roast logging software. 

Looking back now at the first Cropster roast log, I'm amazed how effective our rudimentary pen-and-paper approach actually was! 

One thing we realized straight away was the need for an effective between batch protocol that accounted for differences in green bean temperature. Between winter and summer there was a 23°C difference in the actual temperature of the coffee inside the sacks. We created a formula to calculate the charge and between-batch-cooldown temperatures based on the green bean temp prior to the start of the roast. This gave us really fine control over the turning point, and placed our first gas adjustment around a minute before first crack.

Around this time we also upgraded our gas controls from the original Probat valves, where we could only make gas adjustments in increments of 33%, to a modified ball valve operated by an electric actuator. this gave us very fine, infinitely variable gas control.

The other significant step we took was to build a temperature controlled green bean storeroom, which I'll write about in more detail in my next blog post.

Our machine was approaching 80 years old, but the consistent result we were able to produce time after time were incredible!

During the Last half of 2020 and beginning of 2021 we were busier than we'd ever been before and were in need of a bigger machine. Then came the difficult process of choosing a new roaster. In the end it really came down to a choice between a new Probat, or should we switch to team Loring?

A brand new Loring was seemingly the antithesis of our old Probat, but with all of the effort we'd put into achieving ever more consistent results, the level of automation and pre-programmability it offered seemed a logical next step for us. We chose the Loring and, after a long wait for it to be built (and an even longer wait to get it onto a ship from California!) our S35 Kestrel arrived.

We began the process of translating our Probat profiles and systems into Loring language, anticipating around 6 months to get this right before we thought we'd be able to switch production from the Probat. We managed to get the flavour of our Loring-roasted blends indistinguishable from the Probat roasts in 3 months so, by the start of 2022 we we were doing 100% of our production on the Kestrel.

When we were developing our new profiles we looked into getting tools like a spectrophotometer to match roast level but in the end we found that our tastebuds were our most valuable tool, as well as a propensity to take excessively detailed measurements and notes! 

The control we now have over the flavour of our coffee is now better that it's ever been. As an added bonus, we've freed up around 7 hours a week as a result of larger batch sizes and a degree of automation in our production. This allows us to keep on top of espresso machine servicing and breakdowns and provide much better service to our wholesale customers (with time spare to write the occasional blog post).

Now 82 years old, the old girl still sits proudly in our roastery where she still turns plenty of heads and, while she's no longer a part of our day to day production, occasionally gets fired up to roast a nostalgic batch or two.

After a couple of years, and a few dozen tonnes of coffee roasted on the Loring, I can tell you that the experience of roasting coffee on a modern machine is very different to using an old roaster like our Probat, however, we're now producing better quality, better consistency and better service, and that's ultimately what matters to our customers.