Zeodratation

Man has always been concerned about preserving his food, and has developed numerous techniques/processes to increase the shelf-life of virtually all food products. Many of these methods are based on the principle of reducing water activity in order to inhibit or reduce the development of micro-organisms and limit enzymatic activity. The process/technique used to achieve this reduction in water activity depends on the nature of the food product and its uses. Examples include :

• reducing the quantity of solvent: dehydration ;

• increasing the quantity of solutes: additions of sodium chloride, sucrose, glycerol, sorbitol, acids, bases (lactates) etc., direct mixes between dry and moist foods;

• change of solvent state: deep-freezing, freezing, lowering product temperature and partial transformation of water into ice by crystallization;

• reducing the quantity of solvent and adding solutes: dehydration by immersion/impregnation.

Among all these possibilities, the reduction in the quantity of solvent can be obtained by various dehydration techniques:

• air dehydration (usually hot);

• vacuum dehydration (processes leading to major changes in food products: modification of their flavour, color, structure or the bioactive nature of certain molecules);

• cold dehydration (including freeze-drying).

In the 1990s, three Belgian scientists sought to improve the freeze-drying process by using water traps made of zeolite beads, and came up with zeodration. This technique eliminates the energy-intensive cooling operation associated with freeze-drying. Zeodration is therefore an alternative technique to dehydration or concentration of sensitive products and/or those containing bioactive molecules.