Probat’s attention to the finer details

While consistency may be a key word for coffee roasters, Thomas Koziorowski Director of Product Technology and R&D at Probat, says that at the end of the day, the most important result must be a quality cup.  “Consumers expect consistency in taste without any loss of quality either,” he says. “In the end, taste is what matters.” The importance of a consistent product, however, has become even more relevant in modern consumer trends, with single portion systems, such as coffee capsules or pods, tightening the demands applied to plant technology and machinery. With as little as six to seven grams of coffee per serving, there is little room for error in delivering a consistent, quality product. For instance, plants that choose to blend Arabica and Robusta beans prior to roasting, must ensure that those beans continue to be well blended throughout the process. “If only Robusta beans end up in a capsule, you can imagine how different that product will taste,” says Koziorowski. With this in mind, he explains how consistency must be delivered on different layers. The first being the standard parametres considered in roasting profiles, that is, colour, time and roast temperatures. “But an additional layer is that you need to ensure you’re not getting a ‘demixing’ effect when roasting a blend,” he says. “If you’re roasting both big and small beans together, you need to get the same result in your final product.” The solution lies in the strict separation of heat and movement. Koziorowski explains that air plays a key role in coffee roasting. “For Probat, it has just the single task of convection, nothing more,” he says. “We rely purely on mechanical means to move the roasting product. We consider this principle as one of the cornerstones for consistency and reproducible results. Because it is only the strict separation of movement and energy transmission that allows these to be precisely controlled and thus ensures a homogenous end product.” On that first layer of the standard parametres of a consistent roast, Koziorowski explains how Probat equipment is well set up to deal with the challenges of roasting. “Coffee is a natural product. Its characteristics such as the residual moisture content can vary leading to different reactions during the roasting process,” he says. “Quality indicators like colour, moisture content and roasting time have to be kept consistent, independent from external factors, which are a function of surrounding conditions such as ambient temperature, air humidity and barometric pressure, warehousing conditions, and so on.” Koziorowski also points to seasonal influence on the coffee, such as whether it is a first harvest or a late harvest, that must be taken into consideration when trying to achieve consistency. On all these points, Koziorowski says technology has to compensate for these parametres. He points out that even the most experienced roaster needs support to achieve a truly consistent product. “Technology supports the roastmaster in achieving consistency, rather than replicating it,” he says. He points to Probat’s on-line control systems that provide the roastmaster with tools to monitor and control the roast. One such tool is the on-line moisture measurement system. After a roasting process, the system measures the entire batch and averages out the moisture content. That measurement is fed back into the control system to monitor if it’s on track with the roaster’s requirements. The density of the coffee can be measured via a small sample from each batch. With density an important characteristic in the production of single serve portions, the roaster can better control that density with this constant feedback. With colour a popular measurement of roast quality, Probat provides colour measurement tools such as the Colorette to assist the roastmaster. In addition to these tools to support the operator, Probat equipment has extra features that minimise external factors which might affect consistency. While green coffee preheating is a popular feature that helps save energy, Koziorowski explains how preheating can also help achieve a more consistent product. “When companies keep their beans in large silos outside, they are bringing those beans into the roaster at different temperatures depending on the time of the year,” he says. “However, say you program your preheater to always bring in your beans at 100 degrees Celsius, then your end product will be much more consistent.” Probat equipment also features specially adjusted flaps that help keep the intake pressure inside the roaster at a constant level, by controlling exhaust air quality. While Koziorowski says that the scale of roasting operations should not affect consistency, he does note the challenges many operators face in moving a roast recipe from a smaller to a larger size roaster, or vice versa. To this end, he says Probat equipment is designed to compensate for this move, thanks to its process control system. In addition to changing between equipment, Koziorowski points to the challenge many plant operators face when they need to change between products. For instance, if they need to produce two batches of espresso coffee, then one batch of filter, and then another three batches of coffee for capsules. “When you’re roasting the same product for eight hours, then it’s easier to achieve consistency. However many plants need the flexibility to produce all these products in the same day,” he says. “To switch between these products requires equipment that offers the flexibility to adjust the roasting systems within each batch.” Probat has introduced the Reflection Control Module as a major development in roasting operations. The module allows automatic reproduction of product temperature curves after they have been initially defined. “Actual and target temperatures are permanently compared,” explains Koziorowski. “Any deviations are dealt with by a control system that automatically adjusts the roasting air supply and temperature. This minimises the possible effects of external factors such as batch size, green coffee moisture levels or ambient temperature to a great extent.”