Kinetics of Phase Transition of Native, Cross‐linked, and Hydroxypropylated Rice Starches

Abstract

Kinetics of the phase transition of native and chemically modified rice starches have been investigated by using differential scanning calorimetry (DSC) after isothermal treatment. At the experimental conditions, the phase transition of these starches followed pseudo-first order kinetics. The kinetic order was not affected by the two chemical modifications used, hydroxypropylation and cross-linking, while the rate constants were altered. From the Arrhenius plot, peak temperature (T,) from DSC thermogram appeared to be the turning point for the two steps, swelling and disruption/dissolution, associated in the phase transition of starch granules. When the temperature was below T,, high activation energy was obtained and fell in the range of 61 to 75kcal/mol. Once the temperature was above T,, the activation energy dropped to be in the range of 10 to 30kcal/mol and the starch became less temperature sensitive. Kinetik des Phasenuberganges von nativen, vernetzten und hydroxypropylierten Reissurken. Die Kinetik des Phaseniiberganges von nativen und chemisch modifizierten Reisstarken wurde untersucht unter Anwendung der Differential-Raster-Calorimetrie (DSC) nach isothermischer Behandlung. Unter den experimentellen Bedingungen folgte der Phaseniibergang dieser Starken einer Pseudo-1. Ordnung-Kinetik. Die Kinetik-Ordnung wurde nicht durch die beiden chemischen Modifizierungen, Hydroxypropylierung und Vernetzung, beeinflunt, wahrend sich die Geschwindigkeitskonstanten veranderten. Aus der Arrhenius-Darstellung schien die Spitzentemperatur (T,) des DSC-Thermogrammes der Wendepunkt fur die beiden Stufen, Quellung und ZerreiBung/Auflosung, mit dem Phaseniibergang der Starkekorner assoziiert. Wenn die Temperatur unterhalb T, wurde eine hohe Aktivierungsenergie erreicht und fiel in den Bereich von 61 bis 75kcal/mol. Wenn die Temperatur iiber T, war, so fiel die Aktivierungsenergie in den Bereich von 10 bis 30kcal/mol, und die Starke wurde weniger temperaturempfindlich.

The effect of hydroxypropylation on the structure and physicochemical properties of native, defatted and heat-moisture treated potato starches

“…(compared to native starch) were also observed for hydroxypropytated rice starch by Yeh & Yeh (1993) and Yeh & Jeng-Yune (1996). Butler et al (1986) reported that swelling power (SP) of buffalo gourd root starch was unaltered on hydroxypropylation (MS 0.003 -0.06).…”

“…Hydroxypropylation was shown to alter physicochemical properties of starches (Wootton & Manatsathit, 1984;Butler et a/., 1986;Seow & Thevamalar, 1993;Yeh & Yeh, 1993;Yeh & Jeng-Yune, 1996). Wootton & Manatsathit (1984) showed (using eSC) that increase in MS of hydroxypropylated maize starches (MS 0-0.27) decreased gelatinization enthalpy (6H), onset (To) and peak (To) temperatures, whereas the gelatinization temperature range (Tc -To) remained unaffected.…”

Properties of supercritical fluid extrusion‐based crosslinked starch extrudates

“…Yeh and Li 30 reported that crosslinking increases the heat of gelatinization of rice starch. The crosslinked wheat starches were reported to have virtually changed the onset (T 0 ) and peak (T p ) temperatures values compared with unmodified starch, (T p ) was slightly increased.…”

Effect of the addition of fatty acids on rice starch properties

“…During gelatinization the starch pastes comprise swollen granules suspended in hot water in which molecules of amylose (considered responsible for most of the thickening) are dispersed. The increase in viscosity of a heated paste was attributed (Hsu, Lu, & Huang, 2000;Yeh & Li, 1996a, 1996b to release of an exudate (predominantly amylose) and folding (deformation) of the swollen starch granules. The PV results suggest that the addition of fatty acids, particularly the saturated fatty acid (C18:0) effectively restrained the starch granule from hydration and swelling behaviors during gelatinization.…”