Physicochemical and structural characteristics of cross-linked banana starch using three cross-linking reagents

Banana starch was cross-linked using different cross-linking reagents, phosphoryl chloride (POCl₃), sodium trimetaphosphate (STMP), and epichlorohydrin (ECH), under alkaline conditions. The reaction conditions were selected to produce similar pasting profiles. The effects of the different cross-linking reagents on the physicochemical and structural characteristics of cross-linked starches were evaluated. The microscopy study did not show difference on the surface of the granules. Slight decrease in the peak temperature and enthalpy were found in the cross-linked banana starch. The chemical groups introduced in the starch molecules by the diverse reagents promoted the re-association of starch chains during storage. The rheological analysis of all starch dispersion at 10% (flow curves) showed a non-Newtonian shear-thinning; pastes obtained were time-independent, suggesting an important contribution of the continuous phase. Structural study showed that the cross-linked STMP-starch had the lowest level of amylose and the ratio short/long amylopectin chains. The three reagents used for cross-linking presented different action mode on starch granule and its components.