Probat creates complete colour control


Probat’s new Colour Control measurement system helps increase roast time precision through linking light signals with coffee bean colour.

From pioneering the spherical commercial roaster in 1870 to manufacturing the first tangential roaster in 1969, Probat has always strived to provide the best coffee processing solutions, and continues to evolve the artform today.

Typically when roasting, a combination of time and the coffee bean’s end temperature is used to predict colour and aroma of the final product. However, Probat’s Head of Product Management, Oliver Böwing, and PLC Programmer Tim Ambrosius, say this method is flawed.

“We have known for a long time that a longer running machine results in a different temperature equilibrium. Heat is transmitted into the machine and there is heat transmitted when the coffee is moved outside the machine. It’s not always the same temperature base,” says Böwing.

Using Probat’s new Colour Control system in combination with time and temperature parameters, Böwing says roasters can now consistently and accurately reproduce the same coffee profile.

Oliver Böwing, Head of Product Management at Probat.

“The colour sensor compensates for the unstable heat within the machine and, since it is not directly linked to the roast, can detect changes quicker,” says Böwing.

This, combined with the system’s ability to record the coffee’s properties without interfering with the roast process, alongside the real-time transference of data, offers huge advantages to roasters.

“Previously, it was hard to track the roasting process from outside the machine, but with this Colour Control system, roasters are now able to react quicker,” says Böwing.

“Roasters can detect if a coffee blend is different to the set recipe just by seeing the switch in colour. This can be done instead of the traditional method of checking the temperature with a probe, taking a sample of the coffee beans to the lab, grinding it, and then checking whether it is correct.”

Böwing says this method slows down roast production times. Probat’s Colour Control fixed sensor system consists of a measuring probe, a computational unit, and two infrared light-emitting diode (LED) lights that are placed in a switch cabinet outside the roasting drum. The light of the LEDs is transmitted via a fiber optic cable into the drum.

“This system has the [the computational unit] inside, constantly analysing the roasting process and controlling the sensor probe itself, acting upon information from the light,” says Probat’s PLC Programmer Tim Ambrosius.

“We collect data from the reflected light shone by the two LEDs using special smart sensor equipment.”

This reflected light is recorded as information by the computational unit and transmitted to a programmable logic controller (PLC), or small computer, outside the machine.

This information is put through an algorithm which links the colour with the aroma and roast, calculating a number on a scale from one to 400, which indicates what stage the coffee bean is at. User operators can read the resultant value and make adjustments accordingly.

Probat’s Colour Control system records reflected light.

“This calculation is the key. You can record signals – that is quite easy – but to align it to actually mean something, while taking into account the different coffee beans sizes, qualities, and blends, is difficult,” says Ambrosius.

Beginning nearly a decade ago, Probat started to create this algorithm, which could convert the reflected light signals from the LEDs into a meaningful language, which in turn, reflected the bean’s aroma development and end roast time. The first product created off this technology was the Colorette. It’s most recent version, the Colorette 4, was released in 2017.

“The Colorette 4 represents the latest generation of this laboratory colour measurement device, which also uses LED lights and a special reflection wavelength to measure ground beans to determine the accuracy of the roast,” Böwing says. “We developed the Colour Control system off this because I think engineering wise, it is better to change one thing at a time. In this case, we moved the technology from outside the machine to inside the machine but did not directly change the technology.”

With a roasting environment of up to 500°C and large volumes of steam, the Colour Control system uses purging air to protect it against the elements. The sensor is also sealed with pressurised air to ensure no coffee particles get in the crevices of the unit.

Once the algorithm was created, tests were continuously conducted for a period of a year to further develop the system’s stability and consistency. Done in partnership with Probat’s clients, hundreds of measurements were taken during different roasts with several bean varieties. This test aided in creating guidelines for different varieties.

“From this study we set a base and determined about 20 per cent of possibilities for bean blends,” Böwing says. “But every customer roasts a little differently. So, every time we implement a system, we also take into account the coffee they are roasting, how they are roasting it, and its profile. We don’t just simply install the sensor and that’s it.”

Once installed, Böwing says minimal training is required to operate the Colour Control sensor system.

“Even as an entry-level operator, all you do is follow the instructions on the PLC and roast to the pre-determined number,” Böwing say. “We want to provide our customers with the opportunity to run their operation as smoothly and easily as possible.”

Tim Ambrosius, PLC Programmer at Probat.

Already, the system has generated much customer interest, including the Probat Group’s business division in the food industry for hazelnut and almond production, which also rely on aroma and colour for product development.

For Probat, the next steps are to link its Colour Control sensor system with its reflex automatic and manual systems that form part of the brand’s Pilot 2020 control suite.

This suite links all coffee processing processes in real time to a single enterprise resource planning system. The automatic and manual roasting system add-ons are designed to help roasters increase the consistency of roasting profiles by reducing external influences. By incorporating the Colour Control system into such systems, Böwing says greater batch reproducibility is possible.

“We developed this technology based on Probat’s values to consistently improve our standards and remain as market leaders,” Böwing says. “We have always been on top for technology and for us, this Colour Control system is just the first step.”

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This article was first published in the September/October edition of Global Coffee Report. Read more HERE.

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