Water and food preservation

The water content of food correlates with its shelf life. This empirical observation led to the drying or brining of foods, with the aim of increasing their shelf life. Progressively, science has demystified the role of water, with major spin-offs for the food industry, enabling it to better control the stabilization of food matrices.

Water is the most abundant constituent of food, and its role is central to the food industry. The chemical properties of water explain the diversity of possible interactions with the main food constituents (proteins, carbohydrates and lipids).

The complexity of these interactions continues to be studied, because for manufacturers, water control is not just a question of preservation, but also of the food's physical and sensory characteristics.

The study of water in food remains limited by the heterogeneity of food matrices. Progressively, analytical techniques have made it possible to dissociate the properties of water, leading to the development of several approaches to better understand the behavior of water in food. These approaches are complementary:

• thermodynamic descriptors show the imbalances the food may undergo during processing;

• the more recent kinetic descriptors explain the structural evolution of the food and distinguish between molecular and macromolecular phenomena.

The search for technical solutions to stabilize water raises new questions. The main problem concerns food stabilization through the use of texturizing additives (gelling agents, thickeners, etc.). How can such additives be integrated into the food matrix to ensure they have an optimal effect on water? Can additives stabilize the diffusive capacity of water in food?

The agri-food industry is equipping itself with particularly high-performance analytical resources, and the study of water is bringing the structure of food back into the spotlight. The industry is faced with new challenges, such as preserving native structures.

This article takes stock of the complex issue of water, describing the water/food relationship through selected examples from different food industries.