Characteristics of starch obtained at different stages of purification during commercial wet milling of maize
2014
Singh, Narpinder | Shevkani, Khetan | Kaur, Amritpal | Thakur, Sheetal | Parmar, Naincy | Singh Virdi, Amardeep
Characteristics of starch obtained at different stages of purification during commercial wet milling of maize were evaluated. L*, whiteness index, swelling power, transmittance and syneresis progressively increased while a*, b*, protein content, lipid content and water binding capacity of the starches decreased after each successive purification stage. Protein and lipids content decreased from 5.2 to 0.3% and from 0.15 to 0.03%, respectively, after each successive purification stage. SDS–PAGE indicated that high MW polypeptides eliminated during early stages of purification than low MW. The starches showed typical A‐type XRD pattern along with increasing crystalline region after each successive purification stages. DSC evaluation showed the presence of two endotherms during heating, the first between 69.9 and 81.5°C and second endotherm between 84.1 and 105.3°C being associated with the melting of crystallites and amylose–lipid complexes, respectively. Transition temperatures decreased while gelatinization enthalpy increased with the purification of starch. During cooling, exotherms at peak temperature between 78.8 and 90.3°C was observed. Peak viscosity, final viscosity, breakdown viscosity and setback increased while pasting temperature decreased after each successive purification stage. Storage modulus, syneresis and transmittance of starches revealed increased tendency towards retrogradation with decrease in protein content and lipid content.
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