The production of ice cream, a seemingly simple product, brings into play a variety of complex hydrodynamic and thermic processes, with as yet poorly known interactions. To assist industry in making new products, Cemagref scientists have developed a simulator, the size of a yogurt cup, capable of miming the entire production chain.
Everyone is familiar with and enjoys ice cream. But do we really know how it is produced on an industrial scale? During ice cream’s production process, the starting liquid or semiliquid is placed in the industrial equipment, specifically a heat exchanger, whose internal surface is scraped with the blades of a rotor. The liquid or semiliquid undergoes abrupt and rapid temperature changes and mechanical shearing that substantially modifies its form, particularly its viscosity. This cream is transformed from a liquid state, somewhat like concentrated milk, to a product whose texture is as rigid as soft Italian ice cream.
A consistency that evolves over time
This progression results from the progressive formation of a multitude of small ice crystals, transforming so that the fluid flows within the industrial equipment. These modifications, which vary over time and even within the exchanger, also directly influence the temperatures in the mixture. At this point, the product’s viscosity is evolving continually. Yet the interaction mechanisms operating in the transforming fluid, which flows and becomes more and more consistent, remain poorly understood and controlled. Today, they are a technological obstacle for industry, which is seeking to innovate and create new textures and new products, and a brake to the development of new processes.
A solution that fits in the palm of your hand
Cemagref scientists studying these complex hydrodynamic and thermal processes have developed an experimental tool the size of a 100-ml yogurt cup, making it possible to simulate volumes greater than 500 liters an hour. This simulator can apply the temperature speed changes and mechanical shearing intensities that these products undergo in industrial equipment. With this small prototype, describing and predicting the changes in flow behavior of products are now possible in extreme conditions – at -40°C for example – varying the parameters such as duration, flow speed, pressure, temperature, scraping, and rotor speed. In the laboratory, the simulation of what happens in actual production conditions offers industry new perspectives, making it possible to test a large number of formulations in a short period of time, with obvious cost gains, in the search for new products with hitherto unknown properties.
Another simulator working on a similar principle to study cooking and cooling of milk-based desserts was already patented in 2005, with Danone the industrial partner.
An ANR project in the background
This equipment was developed within the SIMPFRI (Sûreté, Innovation et Maîtrise de l’énergie dans les Procédés Frigorifiques) project. This project was financed by the National Agency for Research (Agence Nationale pour la Recherche; ANR) within its National Project for Research on Nutrition and Human Foods (Projet National pour la recherche en Nutrition alimentation humaine), launched in 2005 by INRA. At the crossroads of process engineering, hygiene, microbiology, and energetics, it aims to better understand the phenomena of microbial contamination in cooling equipment and improve the energy performance of this equipment. The 14 partners involved in this research project bring together skills in hygienics and food safety, fluid mechanics, aeraulics, thermics, and energetics.
For further information: http://simpfri.cemagref.fr/
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