Hygroscopic

The tendency to absorb moisture, which is a condition that occurs with some food products as they are exposed to high humidity. As an example, fleur de sel or French sea salt is very hygroscopic since it often clumps as moisture is absorbed by the particles causing them to cling together in small bunches. Similarly, chicory particles, rice, and other similar foods when exposed to moisture, absorb it and begin to form small clumps. Also, many finely ground particles with hygroscopic properties will often begin to cake together when exposed to moisture, increasing their mass and hardening their texture. Thus, many foods are best kept in air tight containers to not only decrease their exposure to air but also moisture.