Processing methods involving heat, moisture and shear force generally reduce the particle size and change the crystalline structure of the starch. These effects may make starch more accessible to digestive enzymes.Therefore, Starch may be digested more rapidly, leading to shifting of the site of starch digestion. Since gelatinisation increases the access of starch granules to enzymatic degradation, starch digestibility may be expected
to be increased in processed feeds. The extent of starch gelatinisation during pelleting is generally small and is of minor importance. steam conditioning and pelleting will
not have marked effects on cereal starch digestibility. However, during expander and extrusion processing, high amount
of water is added per kg of feed (water addition: extrusion > expander > pellet) and the feed is subjected to temperatures
above 100 ◦C under pressure (temperature involved: extrusion > expander > pellet).