The properties of starches are well-known, however knowledge continues to progress in the understanding of the physicochemical bases of their application.To bind, thicken, texture, stabilise and gel are some of the traditional functions of starch. Native starches are perfectly suited to a wide variety of applications, food or non-food, where their properties remain irreplaceable. Very early however, it appeared necessary, in some cases, to improve the performance of the starch and to respond to the needs of customers, giving other improved functionality or behaviour: solubility with cold water, more stable viscosity with the variations of temperature, hot fluidity, better stability… The first modified starch dates from the 19th century and other modified starches were since then developed, often in partnership with customer industries, which sought to make starches compatible with their industrial processes. In the food area, the principal modifications aim at adapting the starch to the technological constraints resulting for example from cooking, freezing/thawing, canning or sterilisation and to make them compatible with a modern food (microwavable, instant preparations, ultra high temperatures and so on). One of the objectives common to the majority of these transformations is to limit the natural tendency of starch to be retrogress. During the cooking of soup for example, the native starch is hydrated in contact with water. The starch granules expand and the “viscosity” of the solution increases giving it a particular texture. The various modifications of starch make it possible to obtain:
- easier food preparation
- better conservation of food
- better stability of food even when heated under severe conditions (preserves for example, to ensure their sterility)
Main technical modifications:
- Cross Linking is the creation of bridges between the starch chains with specific connections. This process makes it possible to maintain inflated granules and to decrease the loss of viscosity.
- Substitution gives stabilisation property to starch, mainly during cycles of freezing and thawing. This is thanks to molecules which ensure the repulsion between the starch chains, these cannot recombine. The minimisation of the starch retrogradation is thus ensured.