Impact of the Soak and the Malt on the Physicochemical Properties of the Sorghum Starches

Abstract

Starches were isolated from soaked and malted sorghum and studied to understand their physicochemical and functional properties. The swelling power (SP) and the water solubility index (WSI) of both starches were nearly similar at temperatures below 50 °C, but at more than 50 °C, the starch isolated from malted sorghum showed lower SP and high WSI than those isolated from raw and soaked sorghum. The pasting properties of starches determined by rapid visco-analyzer (RVA) showed that malted sorghum starch had a lower viscosity peak value (86 BU/RVU) than raw sorghum starch (454 BU/RVU). For both sorghum, X-ray diffractograms exhibited an A-type diffraction pattern, typical of cereal starches and the relative degrees of crystallinity ranged from 9.62 to 15.50%. Differential scanning calorimetry (DSC) revealed that raw sorghum starch showed an endotherm with a peak temperature (Tp) at 78.06 °C and gelatinization enthalpies of 2.83 J/g whereas five-day malted sorghum starch had a Tp at 47.22 °C and gelatinization enthalpies of 2.06 J/g. Storage modulus (G′) and loss modulus (G″) of all starch suspensions increased steeply to a maximum at 70 °C and then decreased with continuous heating. The structural analysis of malted sorghum starch showed porosity on the granule’s surface susceptible to the amylolysis. The results showed that physicochemical and functional properties of sorghum starches are influenced by soaking and malting methods.

Pasting Properties of White Corn Flours of <i>Anoman</i> 1 and <i>Pulut Harapan</i> Varieties as Affected by Fementation Process

“…Amylase hydrolyzes α-1,4-D-glycosidic bond of starch [16] thus the structure of starch granule becomes more porous facilitating water absorption to granules. This will increase the swelling of granules [17] and increase PV. PV illustrates the capacity of starch in absorbing water and swelling of granules when it is heated [18].…”

Development and standardization of sorghum pasta using extrusion technology

“…With the increasing world population and decreasing water supplies, sorghum is considered as an important future crop. Like other cereals, sorghum is rich in starch-a major storage form for carbohydrates-which makes up about 60-80 % of normal kernels and has excellent potential for industrial applications (Zhang et al 2003;Elmoneim et al 2004;Claver et al 2010). It is a potential source of energy, protein, fibre, vitamins, minerals and phytochemicals (FAO 2005).…”

Effects of Germination Process and Drying Temperature on Gamma-Aminobutyric Acid (GABA) and Starch Digestibility of Germinated Brown Rice

“…Such change of transition temperatures is due to the modification in the lengths of the chains in the starch molecules. During germination, the hydrolytic enzymes break down the hydrogen bond among starch granules, [32] resulting in shorter chain length of starch molecules, and also hydrolyze the intermolecular bonds of starch in crystalline domain. [33] These modifications provided the lower thermal properties of germinated samples.…”