Effect of cross linking on functional properties of cationic corn starch

Native corn starch was cross linked with phosphorus oxychloride (POCl3) before and after cationization to DS 0.04 in an aqueous ethanolic-alkaline solvent with no adverse effects on the cationization reaction rate. Cross linking at six levels of POCl3 (7.5-120 mu l/50g starch) demonstrated that the gelatinization temperatures of cationic starch increased but enthalpies of gelatinization (Delta H) decreased in proportion to the amount of added POCl3. Amylograph viscosities increased with level of POCl3 up to a maximum of 45 mu l POCl3 and then decreased markedly at higher concentrations of POCl3. At 30-45 mu l POCl3, the amylograph viscosities of cationic corn starch increased very rapidly and remained uniformly high throughout the rest of the heating and cooling cycle. At this level of cross linking and cationization, the modified starch could be used industrially as an adhesive or in paper manufacture at more dilute concentrations and with less energy input for mixing the slurry than would be required for cationic starches which exhibit high peak viscosities but negative setbacks on cooling.