Physicochemical Properties of Non-thermally Cross-linked Corn Starch with Phosphorus Oxychloride using Ultra High Pressure (UHP)
2009
Hwang, Duck-Ki | Kim, Byung-Yong | Baik, Moo-Yeol
Corn starch (20%, w/w) was non-thermally and conventionally cross-linked with phosphorus oxychloride (POCl₃; 0.01, 0.05, or 0.1%, based on dry weight of starch) at 400 MPa for 5, 15 and 30 min and at 45°C for 2 h, respectively. Swelling power and solubility of both non-thermally and conventionally cross-linked corn starches were relatively lower than those of native corn starch. The pressure holding time did not affect the solubility and swelling power of non-thermally cross-linked corn starches. X-ray diffraction patterns and relative crystallinity were not significantly altered by both conventional and non-thermal cross-linking. DSC thermal characteristics of both non-thermally and conventionally cross-linked corn starches were not significantly changed indicating that the double helical structure of amylopectin was not influenced by both conventional and non-thermal cross-linking reactions. Both non-thermal and conventional cross-linking greatly affected the Rapid Visco Analyser (RVA) pasting properties, such as increase in pasting temperature and decrease in peak viscosity compared to native starch. This result suggests that in case of cross-linking using POCl₃, both non-thermal and conventional methods result in similar physicochemical properties and non-thermal cross-linking with POCl₃ can reduce the reaction time from 2 h to 15 min. This work shows the potential and possibility of non-thermal starch modification and provides the basic and scientific information on the physicochemical properties of non-thermally cross-linked corn starches with phosphorus oxychloride using UHP.
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