Desiccants such as silica gels, natural clays and calcium oxide are used with dry foods while internal humidity controllers are used for high moisture foods (for example, meat, poultry, fruits, and vegetables). Desiccants usually take the form of internal porous sachets or perforated water-vapor barrier plastic cartridges containing desiccants. They can also be incorporated in packaging material. Humidity controllers help maintain optimum in-package relative humidity (about 85% for cut fruits and vegetables), reduce moisture loss, and retard excess moisture in headspace and interstices where microorganisms can grow
The reaction needs of a proper content of humidity and it can be accelerated
by the presence of electrolytes. Catalysts are commonly used and the most
popular is the chlorine ion, which is usually added in the form of salt
Absorption of water from the small intestine is caused by osmotic gradients that are created when solutes (particularly sodium) are actively absorbed from the bowel lumen by the villous epithelial cells. There are several mechanisms whereby sodium is absorbed in the small intestine. To enter the epithelial cells, sodium is linked to the absorption of chloride, or absorbed directly as sodium ion, or exchanged for hydrogen ion, or linked to the absorption of organic materials such as glucose or certain amino acids. The addition of glucose to an electrolyte solution can increase sodium absorption in the intestine as much as threefold.