Probat clears the air with Proair system

probat proair

The Proair air treatment system from Probat provides large-scale coffee roasters with an energy efficient way to deodorise exhaust air from the cooling process.

The world is changing in many ways. As populations grow, residential areas expand further out from city centres. Businesses are expected to take more responsibility for their impact on their neighbours and the planet. Sustainability is an increasing concern for people, businesses, and governments, with a company’s energy usage, wastage, and emissions under the microscope like never before. 

German coffee roasting equipment and plant manufacturer Probat says as these trends continue to gain momentum, they could prove challenging to coffee roasters. In some cases, they already are.

“Roasting plants were formerly built outside of major cities, like Hamburg or Berlin, but with city growth, they are now in urban areas,” says Oliver Böwing, Head of Product Management at Probat.

“What didn’t use to be a problem, odour from the cooling process, has now become one for crowded areas, especially in parts of Germany, Japan, and the United States.”

Coffee roasting produces many volatile organic compounds (VOCs) and a large amount of air is required during the roasting and cooling processes. This air picks up these VOCs and, if not properly treated, can create a strong odour.

“We’ve been asked more and more frequently by our customers about solutions to remove odours from exhaust air released during the cooling process,” says David Burghard, Area Sales Manager at Probat.

“It’s not very nice for people who live nearby the roasting areas to put up with these odours and smells and some local governments and authorities are starting to intervene.”

In the past, Probat’s focus was on treating exhaust air from the roasting process, using for example a thermal catalyser to heat up the air until the VOCs were destroyed. Cooling exhaust air was rerouted into this system too, and while effective at removing odour, Probat recognised that heating this cooler air was not the most energy efficient solution.

“The topics of energy efficiency and sustainability have become more and more important in coffee, and all industries in general,” Burghard says.

“As a market leader in coffee roasting machinery, we are very aware of our role in the industry and want to provide customers with the best solutions possible, including in regard to energy efficiency.”

In order to find a more sustainable alternative for cooling air exhaust treatment, Probat looked at how other manufacturing industries handled their emissions. 

“There are a lot of experts in the area of odour reduction, so rather than start from scratch inventing something ourselves, we thought ‘why don’t we ask them?’” Böwing recalls.

After doing its due diligence, Probat came across Dutch company Aerox, which employed a novel cold plasma technology in its Aerox Injector odour reduction system.

Thomas Elshoff, R&D Engineer at Probat, says the plasma technology is non-thermal, meaning it does not rely on heat to transform the VOCs in the exhaust air.

“Fresh air enters the system through a three-stage filter to ensure it is clean and a heater to control the moisture of the fresh air. From a high voltage power unit, we generate these small ‘lightning bolts’ that transform that fresh air into ‘oxygen radicals’. These radicals react with the cooling exhaust air, oxidising the odour molecules resulting in an efficient reduction of the smell or odour,” Elshoff says.

While the Aerox Injector had potential, the unique demands of coffee meant the system would need to be adapted to fulfil the needs of roasters. Probat partners with Aerox to make this happen, debuting the resulting Proair unit during a Probat Heat Series online presentation via the company’s Facebook and YouTube channel on 15 April, 2021.

“Proair is a good marriage of two excellent technologies and sources of expertise, Probat in coffee roasting and Aerox in odour control. It took a lot of work to combine them in an efficient way that would work for the coffee industry,” Böwing says.

First and foremost, Probat had to ensure the odour reduction system used in other industries would be able to process the unique aroma of coffee roasting. Before starting the development of Proair, Probat set up a small test unit in its R&D Center in Emmerich, Germany. Following some strong results, the manufacturer installed and tested a pilot industrial size system in a roasting plant for six months to ensure those results were stable and reproducible.

“Perhaps most importantly, unlike other systems, Proair has no influence on the actual cooling process of the coffee,” Elshoff says.

“There’s also no need to stop the roasting process should there be some disturbance to the air treatment system. You can continue your production while the issue is resolved.”

Olfactometries on coffee roasters using Proair show a reduction in odour emissions by at least half. With the odour reduction system living up to its potential, Böwing says the greatest challenge in adapting the system to coffee was making sure it could run as efficiently as possible.

“Within one hour, we use the cooling system of the roaster for about 20 minutes. We could have the Proair run continuously, but it would be a waste of energy since we only need it one third of the time,” he says.

“Instead, we integrated the Proair system into our roaster controls to ensure the best process possible. It receives a signal from the roaster when the cooling process begins so it knows to activate the plasma modules and begin air treatment.”

Proair provides energy savings of at least 75 per cent, compared to Probat’s past partial cooling air treatment. The non-chemical process of Proair means no fuel sources other than electricity are required for cooling air treatment and the plasma modules can be refreshed and parts of it reused again. Apart from the filter elements, which have to be cleaned after a certain operating time, there is no further waste in this process.

The Proair is also easy to install thanks to the system’s compact size and compatibility with roasting equipment from other manufacturers.

“The Proair system doesn’t need too much space and a big advantage of it is that you can integrate it into existing roasting systems,” Burghard says.

“But the most important thing is that, with a maximum air volume of up to 220,000 cubic metres per hour, Proair can meet the needs of any large-scale industrial roaster.”

While the Proair unit itself is relatively small for such a high capacity, a decent pipe length is required to provide enough reaction time for the plasma to reduce the odour of the exhaust air. In cases where this could be difficult to achieve, Proair can even be installed outside on the roof of the roasting plant or at a position within the cooling pipe where the best efficiency can be reached.

Böwing recommends Proair for use with larger roasting machines. Probat offers the solution alongside roasters ranging in size from its Px 120 drum roaster to its 5000-kilogram-per-hour Jupiter model.

“Not every coffee roaster is going to need a system as advanced as Proair, but for those that do, it will be a very important piece of technology,” he says.

Proair is one of several developments Probat intends to bring to the market in 2021. Böwing says through the Heat Series, the coffee industry can look forward to continued updates on Probat’s development projects throughout the year.

“Every month we’ll host a webinar giving insight from Probat on new technology we’re bringing to the coffee market,” he says. “These will cover topics ranging from Colour Control technology – roasting by colour instead of temperature or time – to new machine releases and regular updates to our Pilot Control software systems.”

Probat will also continue to work on the Proair system, with expanded applications of the air treatment system already on the manufacturer’s mind.

“This is the beginning, not the end, of our development with Proair,” says Böwing. “We have begun with integrating the system with our roasters, but we’ve also heard the desire of our customers for a plant-wide solution. That will be our next stage with this product.”

For more information, visit or view the Probat Heat Series episode on Proair at

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