Physicochemical properties of granular and non-granular cationic starches prepared under ultra high pressure

•Starch reactivity in UHP-assisted cationization was influenced by starch sources.•Granular cationic starches possessed higher swelling power and lower solubility.•Flocculating activity of granular cationic starch was better than its counterpart.•Granular one revealed similar flocculating activity regardless of reaction scheme. Granular and non-granular cationic starches were prepared through the reaction of tapioca and corn starches with 2,3-epoxypropyl trimethyl ammonium chloride (ETMAC) using conventional and ultra high pressure (UHP)-assisted reactions. The cationic starches were characterized with respect to morphology, degree of substitution (DS), FT-IR, 13C NMR, X-ray diffraction pattern, solubility and swelling power, pasting viscosity, and flocculating activity. Non-granular (relative to granular) cationic starches possessed higher DS values. While DS values of non-granular cationic starches were lower for UHP-assisted (relative to conventional) reaction, granular cationic starches did not differ for both reactions. For flocculation activity, granular cationic starches with lower solubility and higher swelling power were higher than non-granular counterparts with reversed patterns in solubility and swelling power, regardless of conventional and UHP-assisted reactions. Overall results suggested that flocculation activity of cationic starches may be directly associated with their swelling powers (relative to DS values).