Effect of Cross Linking on Functional Properties of Cationic Corn Starch
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English Slovak |
| ISSN: | ISSN 0038-9056 |
| Online Access: | http://www.viks.sk/chk/star_11_97_458_464.doc |
| Abstract: | SUMARRIES. Native corn starch was cross linked with phosphorus oxychloride (POClj) before and after cationization to DS 0.04 in an aqueous etha-nolic-alkaline solvent with no adverse effects on the cationization reaction rate. Cross linking at six levels of POC13 (7.5-1201/50g starch) demonstrated that the gelatinization temperatures of cationic starch increased but enthalpies of gelatinization (AH) decreased in proportion to the amount of added POC13. Amylograph viscosities increased with level of POC13 up to a maximum of 451 POC13 and then decreased markedly at higher concentrations of POC13. At 30-45/l POC13, 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 cat-ionic starches which exhibit high peak viscosities but negative setbacks on cooling. CONCLUSION. Corn starch could be effectively cationized and cross linked with POC13 in an aqueous ethanolic-alkaline solvent in either sequence with no effect on cationization reaction rate. At high concentration, cross linking decreased the swelling power and solubility of cationic starch, as well as the enthalpy of gelatinization. These results indicated that cross linking occurred largely in the amorphous regions of the starch granule, limiting the ability of the granule to take up water, swell and elute the amylose molecules. When evaluated at lower concentrations of cross-linking reagent, the optimum level (30-45 1) gave high, stable amylograph viscosities with almost no peak viscosity or set-back. These characteristics were highly desirable in paper making because strong adhesive properties could be achieved with dilute solutions of cross-linked cat-ionic starch, and the energy requirements for mixing the slurry would be minimized. |
|---|---|
| ISSN: | ISSN 0038-9056 |
