Electrophoretic and DSC studies on different wheat starches with various amylose contents
Granule-bound starch synthase and the structural and thermodynamic properties of the isolated starches were compared using amylopectin (2.1% amylose content), normal (20.5-25.1% amylose content) and high amylose (≥39.5% amylose) wheat cultivars of Japanese, Italian and Russian selections. Amylopectin (2.1% amylose content), normal (20.5-25.1% amylose content) and high amylose (amylose rich containing ≥39.5% amylose) wheat cultivars were investigated using an electrophoretic technique to examine starch-granule bound synthase. High-sensitivity differential scanning microcalorimetry was used to examine the structural and thermodynamic properties of extracted wheat starches. Wx-B1 protein was not present in normal and even in high amylose cultivars except for the normal amylose cultivar Bilancia. An increase in amylose content in starches is generally accompanied by a decrease both in the melting enthalpy and the melting temperatures of crystalline lamella, whilst the polymorphous structure of starches remains invariable (A-type). The melting cooperative unit, the thickness and the surface free energy, enthalpy and entropy of crystalline lamella were also determined. Classification of wheat starches with different amylose contents is offered.
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