Explain Water Holding or Hydration Capacity (WHC) and Viscosity?

WHC refers to the 'ability of fibre to bind water', just as dry sponge does when soaked in water. WHC of the fibre is influenced by a variety of factors. These are listed as:

Solubility

• Ph of the gastrointestinal tract,
• Size of the fibre particles.

Many water-soluble fibres such as pectin, gums and some hemicelluloses have a high WHC. Further, pectin, gums and mucilage form viscous, solutions with the gastrointestinal tract. Cellulose and lignin have a low WHC.

These fibres:

• Delay emptying of food from stomach;
• Reduce mixing of gastrointestinal contents with digestive enzymes;
• Reduce enzyme function;
• Decrease nutrient diffusion rate and delayed nutrient absorption; and
• Alter small intestine transit time