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Staff Report
Usually, the roasting and grinding processes are the main focus of coffee refinement. Third parties often underestimate the complexity of a coffee production plant. The configuration of the various plant components between green coffee feeding and packaging machine has to guarantee a flawless and efficient throughput.
Clean coffee as a basis for quality
The first plant throughput step, delivery of the coffee, makes specific demands on green coffee feeding: bin sizes and conveying capacity of downstream transporting systems have to be able to cope with the delivery volume in a certain timeframe. Suction plants absorb the dust released during the discharge of coffee bags, big bags or containers.
Bin scales positioned downstream to green coffee reception determine the amount delivered. For quality control reasons and in order to protect downstream components against damage, various cleaning machines rid the coffee of foreign particles. While a wind sifter reliably separates coffee bag strands as well as fibers and other materials specifically lighter than green coffee, circular sieve cleaners extract smaller or larger solid objects from the coffee. Alternatively or complementarily, a color sorting machine with integrated material detection can weed out both smaller foreign objects and those deviating in color. Metal separators effectively rid the green coffee of ferrous and nonferrous metals. After cleaning but prior to storage, the coffee is again weighed. Transport systems then convey the coffee into silos that guarantee protected storage until further processing takes place. Conveyance of green coffee takes place via both mechanical and pneumatic systems.
Reproducible roasting results – consistent good tasteDuring "Blending Before Roasting" (BBR), green coffee blends are composed just prior to the roasting process using a blending scale. Software specifically designed to identify deviations within the weighing process continually calculates a correction factor for ensuing weighing processes. As the roasting machine mixes the blends homogenously via the circular rotation of the drum, the roaster bowl or the paddle system, the use of an additional mixer is not necessary.
Serving of the roaster takes place largely pneumatically via a high-pressure or high-suction conveyor system. The roaster refines the green coffee producing a roasted coffee with the desired characteristic aroma. Modern exhaust air treatment systems such as the Ecologist Proforte guarantee an efficient cleaning of the roast exhaust air. The chaff emerging during the roasting process is processed via briquette or pelletiser plants so that it can be disposed of in an environmentally-friendly and economic way.
The roast master administers all roasting parameters such as roasting time as well as product and roasting supply air temperatures centrally using a user-friendly roaster control. The additional Reflex Automatic function allows the reproduction of a prior roasting profile and is thus another important element of quality assurance during the various processing steps.
Cleaning and weighingIn the case of the Neptune drum roasters, cleaning of green coffee takes place via a high-suction destoner. It separates the fresh coffee from foreign objects with a higher specific weight. Alternatively, stone separators or color sorting machines can be used, such as in the roast systems of the Saturn or Jupiter series. Besides cleaning, color sorters also enable coffee-bean selection according to degree of color based on two colors. A metal separator additionally installed in the conveyor line rids the roasted coffee of metallic contamination.
The cleaning of roasted coffee is a core issue and takes place for two main reasons: It protects downstream components, particularly grinders, from damage induced by foreign objects. This reduces costs in terms of spare parts and extensive repair work that can lead to expensive machine downtimes. Moreover, thorough cleaning is an important element of quality assurance. With the trend towards the "whole bean", requirements for a qualitatively high-grade final product have increased: End consumers demand roasted coffee free of contamination and with a consistent bean pattern. The color sorter significantly improves bean patterns.
Following the cleaning process, the coffee is again weighed using a bin scale to control shrinkage and determine the actual amount of roasted coffee. As roasted coffee has a higher breakage sensitivity than green coffee, it is usually transported to the storage bins via mechanical conveyor systems such as bucket elevators or belt conveyors. Just as in the green coffee area, roasted coffee is largely stored in compartment silos, which are characterised by a high degree of flexibility in terms of layout and contents.
In "Blending After Roasting" (BAR), a blending scale mixes various roasted coffees to produce roasted coffee blends. A specifically developed software for Probat’s blending scales that minimises off-target deviations can be used with BAR as well. A homogenous blending of various select roasted coffees is an essential prerequisite for a consistent taste in the cup. For this purpose, a paddle mixer caters for an even distribution in this process step. The paddle mixer scale merges two plant components: Right after weighing, it mixes the coffee in the same machine. Depending on the final product desired – "whole bean" or ground coffee –, the transport of the coffee to the packaging machine or to the grinder follows.
Grinding of roasted coffee is a further core aspect of coffee refinement. Whether filter coffee, espresso or Turkish-fine coffee: Uniform degrees of grinding within the coarse to super-fine spectrum are decisive for the later use and quality of the ground coffee. Roll mills with up to three grinding passages attain a reproducible grain spectrum. Cooling the rollers additionally protects coffee aroma here.
Gas-tight ground coffee bins store the freshly ground coffee and protect the aroma during the degassing process. The bins are constructed in a way that prevents the aroma-detrimental entry of oxygen, which would cause an ‘aging’ of the coffee. The carbon dioxide discharged by the ground coffee escapes via a valve.
After a certain defined degassing period, a suction-impulse conveying unit transports the coffee to the packaging machine via a recirculating conveying gas. To ensure aroma protection, this takes place without oxygen. If necessary – with "Blending After Grinding" (BAG) – a paddle mixer or bin scale ensures the composition of different coffees for targeted ground coffee mixtures. Prior to packaging, a redensifier increases the bulk or stamped density of the ground coffee to guarantee uniform, reproducible filling levels in the coffee packages.
Plant controlThe central plant control coordinates the work processes of all plant components. It ensures an efficient throughput of coffee within the whole plant and facilitates the administration and evaluation of data as well as recipes significantly. Computer monitors visualise the whole production plant with all machines and equipment. In this way, the operator can monitor and control ongoing production at any time. The optional integration of online-moisture and inline-grain measurement allows for an additional optimisation of the process.
Probat’s know-how is based on 140 years of experience in the construction of coffee production plants and equipment. Besides equipping customers technically with individual components or all-in-one solutions, the company also offers planning services as well as training courses. As a full-line supplier, Probat covers the whole range from the very first planning idea to the commissioning of the coffee roasting plant.
Probat-WerkeThe Probat-Werke von Gimborn Maschinenfabrik GmbH based in Emmerich has a market share well above 50%. Probat has been operating globally for decades and is a global leader in the market segment of coffee roasting machines and equipment.
Since its establishment in 1868 the development, manufacturing and sale of processing equipment for turning green coffee into roasted coffee has been the focus of company activities. Quick drum roasters as well as large-scale series "G" roasters were one of the reasons that the sale of the first 100,000 roasters was celebrated in 1938.
The name PROBAT stands for innovative roasting in cocoa processing too. Bauermeister, a company belonging to the Probat Group, was established as early as 1882 and has been a synonym for optimal cocoa processing for decades. In this way, Probat also possesses unique know-how in food processing.
An in-house museum for coffee technology in Emmerich documents the history of technical developments and provides the visitor with rare glimpses into the old world of coffee.
At its locations in Emmerich and Norderstedt Probat employs about 400 people in Germany alone. Worldwide it has over 600 staff working in various companies in Italy, the US and Brazil. Probat exports about 80 percent of its products, particularly to Europe, North America and Central and South America.