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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 , 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.
Opportunities for smaller businesses
The chocolate and cocoa market is a fast-evolving market. According to recent research, the demand for chocolate in Europe is predicted to grow by a compound annual growth rate of 3 %, between 2018 and 2022. While Europe is the world’s largest producer, the bulk of this production rests with six big multinationals.
Additionally, despite advances in food production, cocoa is still one of the products that goes through a high number of stages prior to consumption. The quality of the finished product is dependent on the multiple steps and the quality of the treatment it undergoes.
The BAT system offers chocolate manufacturers a more effective solution as they refine their products in the pursuit of higher quality. Importantly, it also opens up opportunities for producers to produce chocolate directly from the bean, while avoiding the cost associated with multiple cocoa processing machine.
“BAT controls the temperature of the core of the product much better than current technologies throughout the refining cycle. This makes it possible to produce different chocolates from the same cocoa beans.
“This could lead to an increase in the quality of finished products on the market, as well as new opportunities for smaller businesses, as the barriers to entry are reduced,” says Marello.
The team are currently pursuing further funding opportunities in order to develop an industrial-scale prototype, capable of running 24 hours a day.
A lot of time has passed since the first refiner conches were built to make chocolate. At that stage all necessary processing steps were done in the same chocolate tempering machine, which sometimes took a week to get the final product. This paper is not intended to summarise all the technical developments since then as such information is available in textbooks1. Instead it aims to briefly introduce the different systems for chocolate mass production offered by various companies in order to give readers an overview on what is currently available on the market.