Ice cream, ice and sorbet Physicochemicals aspects

Ice creams, a generic term that describes a family of products, are highly elaborate and original food preparations in more ways than one. From a physico-chemical point of view, ice cream's structure is extremely complex, representing the three states of matter and organized in such a way as to include no fewer than six different dispersed systems. In addition, ice cream's high air and water content makes it an attractive product, not only economically for the manufacturer, but also for the consumer, who is looking for both pleasure and a way to take the sting out of their guilt - air and water being inexpensive and flavourless! What's more, it's the only frozen food that can be cut, shaped into balls or dumplings and eaten, all at a temperature below 0°C. The reasons for this special status are due, on the one hand, to a greater or lesser air content with a foam-like structure (dispersion of air in a liquid matrix) and, on the other, to the minimization of the existence of solid water in the form of pure water ice crystals. Finally, from a commercial point of view, and this is particularly marked in France, ice creams remain festive, gourmet and seasonal products, with two sales peaks: in summer, with individual products (cones, sticks, bowls, etc.), and at the end of the year, with specialities to share (logs, cakes, etc.). This relative under-consumption, at 6 liters per year per inhabitant compared with other countries in Northern Europe (14 liters for Norway), North America (22.5 liters for the United States) and New Zealand (27 liters), can be explained for France in part by competition at the end of the meal, which can be attributed to products that are firmly anchored in French eating habits, namely fermented milks, dairy or pastry desserts, and fresh fruit. That said, the frozen desserts sector has seen slight but steady growth in value since 2005, averaging 2% a year, with sales of 1.1 billion euros in 2016, due in particular to innovation in terms of both products and packaging.

The aim of this article is to present the microstructure of frozen desserts, with its various components and its highly complex organization, which makes it a relatively unstable, dispersed system. This microstructural approach allows us to better understand the risks of disorganization of such a system, and to discover the various means that can be implemented to guarantee consumer satisfaction, bearing in mind that the weak point in terms of spoilage of these products lies in maintaining a sufficiently low temperature throughout the product's lifespan, without breaking the cold chain!

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