Starch is one of the most valuable polymeric carbohydrates
due to its functionality that imparts to products in various
industries. It is commonly used as a thickener, colloidal
stabilizer, gelling, bulking and water preserving agent. The
physicochemical and functional properties of starch systems
and their exclusivity in a variety of food products
differ with starch biological origin. Even though, restrictions
such as low shear resistance, thermal resistance and
disintegration and high affinity toward retrogradation have
limited its utilization in some industrial food applications.
These shortcomings can be overcome by starch modification
using chemical, physical and enzymatic methods or a
combination of them. The latter is called dual modification
which has been used when single methods do not provide
satisfactory results. Limited work has been published on
the effects of dual modification as a combination of
chemical and physical methods (i.e., cross-linking and
annealing) on the functional properties of starch.
Among different chemically modified starches, crosslinked
starch plays an imperative function in food products
to thicken, stabilize and give texture [1]. Cross-linking of
starch strengthens the hydrogen bonds in the granule with
chemical bonds that execute as a bridge between the starch
molecules [2]. Chemical composition of the cross-linking
agent, reagent concentration, pH, reaction time and temperature
are momentous factors in the cross-linking reaction.
POCl3 is an efficient cross-linking agent in aqueous
slurry at pH 4–11 in the presence of a neutral salt. Thus,
hydrophilic phosphorus groups straight away react with the
starch hydroxyl groups, forming distarch phosphate [3].
The covalently linked network makes cross-linked starch
swells less and shows more stability under shear, high
further applications.