How does hydration affect digestion? My textbook( biochemistry by Satyanarayana, 4th edition pg.no:166) says: > The polysaccharides get hydrated during heating which is essential for their efficient digestion. ( _I think there is a typo , heating should be replaced with eating_ ) How does water add into polysaccharides? Am I right if I say it is by hydrogen bonding? It also says that efficiency increases, is it so because the substance is now more diffused so that enzymes act on an effectively larger surface area(making colloidal solution)? Or if the added(hydrated) water plays some role in interaction between enzyme and polysaccharide?

That's not a typo. The author is talking about cooking polysaccharides (gelatinisation), which in fact increases the digestibility:

> Gelatinization refers to the irreversible loss of the crystalline regions in starch granules that occur upon **heating** in the presence of water. The temperature range during which the crystalline structure of the starch granule is lost is dependent on the water content, and on the type of starch. The gelatinization **dramatically increases** the availability of starch for digestion by amylolytic enzymes. (emphases mine)

Source: FAO: Effects of Food Processing on Dietary Carbohydrates.

You can read more about it in this Wikipedia page.