Effect of hydrothermal treatment on the physical and rheological properties of maize starches

Abstract

Abstract.Standard maize (SMS) and waxy maize starch (WMS) were hydrothermally treated at their residual moisture level (~12 %) by Instantaneous Controlled Pressure Drop process in order to obtain pre-gelatinised starches in a single step. The effect of two parameters of this process, namely the steam pressure level and processing time, on the structural and rheological properties of the native maize starches were described. The occurrence of partial gelatinization for DIC treated starches was clearly attested by the increase of the median volume diameter in cold water, the decrease of the gelatinization enthalpy and a loss of birefringence under polarized light, this was more prominent for the highest pressure and longest time: 2.7 to 3 bar for 200 to 300 seconds.Sensitivity of starches to the process was also dependent on their origin, SMS being more affected than WMS.

Study of DIC hydrothermal treatment effect on rheological properties of standard maize (SMS), waxy maize (WMS), wheat (WTS) and potato (PTS) starches

“…The measure was repeated three times. The volume distribution was obtained according to the Mie scattering theory (Loisel et al, 2006). From each distribution, the median volume diameter (D V , 0.5 ) was presented and the swelling ratio was defined as (D/D 0 ) 3 , with D and D 0 the median diameters of treated and native starch, respectively (Nayouf et al, 2003); the size distribution was evaluated using the dispersion index referred to as the span, by the following equation:…”

“…The different evolution of the swelling ratio (D/ D 0 ) 3 clearly underlines the differences between starches: SMS and WTS present the highest swelling capacities at 3 bar/5 min of 105.7 and 327.6, respectively. Such a behaviour, particularly for WTS, reflects the cold swelling of DIC treated starch granules; it is not mentioned in the literature for HMT treated starches and has been ascribed to partial loss of crystallinity and subsequent enhanced capacity to hydration (Loisel et al, 2006).…”

“…Consequently, the residual structure after the DIC treatment contained crystallites with a greater stability (cohesion) (Maache- Rezzoug et al, 2008). Preliminary studies on standard and waxy maize starches (Loisel et al, 2006;Zarguili et al, 2006) showed that the thermal properties of DIC treated starch depend on the processing time and the steam pressure level. Increasing these two parameters induces an increase in the onset (T onset ) and in the peak (T peak, ) temperatures of gelatinization and a reduction in gelatinization enthalpy.…”

Preparation of poly(lactic acid) and modified starch composites

“…Starch [23] is a nature biodegradable polymer. Because of its abundant output and low cost, starch is the preferred material for the modification of other polymers.…”

Quality dynamics of maize ‘tuwo’ (non-fermented maize-based dumpling) as influenced by steaming of maize grits at different resident time

“…Pregelatinisation of starches in cereal grains is one physical method through which the functionality of the starches can be modified and it has been carried out on such cereals as rice (Lai 2001), maize (Loisel et al 2006;Lagarrigue et al 2008) and millet (Adebowale et al 2005). This physical modification of cereal starches, through pregelatinisation, is usually accompanied by such changes as granule swelling, loss of birefringence and crystallinity, disruption of starch granule structure, among others (Lai 2001).…”