Starches are modified chemically or physically or both to accentuate their positive characteristics, diminish their undesirable qualities, or add new attributes. Common limitations associated with native normal starches are excessive viscosity at low solids content (difficulty in handling, lack of body), high susceptibility to retrogradation (gel opacity, syneresis, and lack of freeze–thaw stability), and lack of process tolerance. By proper modification, changes can be made in one or more of the following attributes.
- Ability to act as an emulsifying agent
- Ability to act as an emulsion stabilizer
- Ability to encapsulate
- Charges on starch molecules (via adding positive or negative charges)
- Cold-water swellability
- Cooking characteristics (degree of breakdown, degree of setback-retrogradation, energy required to cook, gelatinization/pasting temperature, hot-paste viscosity)
- Digestibility
- Film formation
- Flowability
- Interactions with other substances
- Paste and gel characteristics (adhesiveness, clarity, freeze-thaw stability, gel strength, rate and extent of syneresis, retrogradation stability, sheen, viscoelasticity, viscosity)
- Process tolerance (pH tolerance, shear tolerance, temperature tolerance)
- Solubility in hot and room-temperature water
- Stability in high-salt environments
- Water resistance of films (water resistance or water-holding capacity)