Effect of cross‐linking on some properties of potato ( Solanum tuberosum L.) starches

Starches separated from different potato cultivars were modified using two different cross‐linking agents: epichlorohydrin (EPI) and phosphoryl chloride (POCl 3 ) at different concentrations (1.0 and 2.0 g kg −1 POCl 3 ; 2.5, 5.0 and 10 g kg −1 EPI). Differential scanning calorimetry, rheological and retrogradation measurements were performed to characterise the influence of cross‐linking on the properties of potato starches. Cross‐linking considerably reduced swelling power, solubility, water‐binding capacity and paste clarity. The decrease became greater as the reagent concentration increased. The starches treated with 1.0 g kg −1 POCl 3 exhibited exceptionally higher swelling power than their counterpart native starches. Neither cross‐linking agent caused any change in morphology of the starch granules. Studies on the phase transitions associated with the gelatinisation showed significantly higher values for the onset temperature ( T o ), peak temperature ( T p ), conclusion temperature ( T c ) and enthalpy of gelatinisation (Δ H gel ) for the cross‐linked starches than the native starches. Starches treated with both the reagents showed lower peak storage modulus ( G ′) and loss modulus ( G ″) than their native counterparts. The tendency of the starch pastes towards retrogradation increased considerably with increases in storage duration. However, the starches treated with 1 g kg −1 POCl 3 exhibited much lower syneresis than the other cross‐linked starches.