INTERACTIONS BETWEEN STARCH AND LIPIDS STUDIED BY DSC

Differential scanning calorimetry is a valuable method for obtaining information about starch-lipid interactions. The transition of the amylose-lipid complex and the influence of lipids on starch gelatinization and retrogradation have been studied. The thermal transition of the amylose-lipid complex depends on monoacyl chain length and the polar head of the lipid, on the water content and on the type of starch, i.e. when amylose is present in the form of starch granules. Different polymorphic forms of the amylose-lipid complex exist. Food processing, e.g. extrusion cooking and drum drying, might lead to very different types of complexes. Chemical modification of the starch also affects the thermal properties of the amylose-lipid complex. Indirect evidence is given for the formation of an amylopectin-lipid complex. This evidence includes the decrease in gelatinization enthalpy for a waxy maize starch in the presence of lipids, and the reduced retrogradation of waxy maize starch in the presence of lipids. The influence of the lipid on the complex formation is shown. It is stated that not only the monoacyl chain length and the polar head but also the phase behaviour of the lipid influence the properties of the complex. The lamellar liquid-crystalline phase is much more effective for complex formation than, for example, the cubic phase.