A review of a machine design of chocolate extrusion based co-rotating twin screw extruder Aziendale

A review of a machine design of chocolate extrusion based co-rotating twin screw extruder

Based on innovation and competitive market for food industry, there are several food products which have been designed to attract customer. Since there is USD 39,431 millions of chocolate sales in 2018, USA [1], chocolate product shapes have been developed based on manufacturing process. This paper presents a review process of a cocoa machine design of chocolate extrusion based co-rotating twin screw extruder. A property of suitable chocolate for extruder was established. The pros and cons of machine extruder for food processing including, a screw extruder design were exposed. Since there were problems in the chocolate extruder, the process parameters such as barrel temperatures, feed rate, screw speed, motor load and melt pressure were established. These parameters would be applied to design screw extruder for chocolate processing.

Demand is growing for higher-quality chocolate, alongside more sustainable manufacturing processes. But current chocolate production faces problems keeping up. The different production stages rely on their own specific cocoa equipment, components can be difficult to clean and potentially harmful metal particles can be released into finished products.

EU support helped the BAT project optimise the chocolate manufacturing process with a versatile ‘one-stop shop’ machine which, as well as being easy to clean, avoids the need for producers to run a set of expensive, bulky and energy-intensive machines.

The new refining technology

There are typically around seven stages to chocolate manufacturing involving three to five dedicated machines. First, beans are toasted before husking to remove the shell surrounding beans. The resulting cocoa goes through a pre-refiner before passing through a refiner to create a smoother consistency. Next, the ingredients enter a separator which ensures no grains are too large before going through a further refining stage. The last stage is conching in which the acidity of the cocoa is removed.

The BAT solution combines the pre-refining, refining and conching stages into a single step, reducing the number of machines needed for the process to a single machine. Importantly, the machinery is designed to be easy to clean and does not release metal into the product.

Crucially, it can also refine both products containing water (mix hydrated) and those without anhydrous, something that is not possible with current technology. The icing on the cake is that it comes at a comparatively low purchase price.

The team built a prototype BAT refining head, to carry out tests.

“The refining head is the processing step on which our innovation is based. We had a number of challenges to overcome with these tests, such as keeping temperature and quality constant across the whole product batch. Despite the complexity we managed to solve these with our design,” says Stefano Marello, project coordinator.