Effect of Moisture Content on the Melting of Wheat Starch

Abstract

The effect of water on heating wheat starch-water mixtures of water content (between 2.8% and 90%) has been observed by differential scanning calorimetry. Four endothermic transitions were observed for wheat starches heated in the presence of limited water (moisture levels of 40,50%). These transitions appears to be due to melting of amylopectin crystallites, amylose-lipid, and arnylose. The heat decomposition temperature range of wheat starch were 253-302OC and the plasticization effect according to the amount of water was small. The melting temperature obtained by extrapolation to zero volunme fraction of water were 234°C for M1 DSC endotherm, 254.3OC for M2 DSC endotherm, 267.8"C for M3 DSC endotherm. EinfluB des Feuchtigkeitsgehaltes auf das Schmelren vonWeirenstllrke. Der EinfluB von Wasser auf die Erwarmung von Starke-Wassermischungen (zwischen 2,s und 90%) wurde durch Differential-Raster-Calorimetrie beobachtet. Vier endotherme Ubergange wurden bei Weizenstarken beobachtet, die in Gegenwart begrenzter Wassermengen erhitzt worden waren (Feuchtigkeitsgehalte 40,50%). Diese Ubergange scheinen verantwortlich zu sein fur das Schmelzen von Amylopektinkristalliten, Amylose-Lipid und Amylose. Der Warmeabbau-Temperaturbereich von Weizenstarke war 253-302OC, und die Plastifizierungswirkung war entsprechend der Wassermenge gering. Die Schmelztemperatur, die durch Extrapolation auf die Nullvolumen-Wasseranteile erhalten wurde, betrug fur die M1-DSC-endotherme 234"C, fur die M2-DSC-Endotherme 254OC und fur die M3-DSC-Endotherme 267OC.

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

“…A study (Jang & Pyun, 1996) of wheat starch in the presence of limited water (40, 50% moisture) showed the appearance of four endotherrns ( Fig and M2 and M3 coalesced into a single band [M2+M31 (Jang & Pyun, 1996). Biliaderis at al.…”

Investigation of the gelatinization and extrusion processes of corn starch

“…Gelatinization, which is influenced by the presence of other solutes, is preceded by swelling and provides irreversible changes in properties. 16,17 When the disruption of the crystalline regions is reached in the presence of a low content of water, the process is denominated as melting. 18 Industrially, thermal and mechanical energy input associated with the addition of plasticizers, such as water and glycerol, are necessary to transform granular starch into a homogeneous matrix.…”

Thermoplastic starch/wood composites: Interfacial interactions and functional properties

“…Starch itself cannot be processed with traditional thermoplastic processing technologies because of the large size and stiffness of the molecules, and the resulting high glass transition temperature. Because of strong hydrogen bonds developing among the molecules, neat starch cannot be melted and processed without further treatment (Jang & Pyun 1996;Swanson et al 1993). Chemical modification and plasticization partially resolves these problems and plasticized starch can be processed by extrusion, injection molding or other processing methods.…”