Multi-scale structural and digestion properties of wheat starches with different amylose contents

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Summary

The physicochemical and digestion properties of three wheat starches with different amylose contents were studied. Scanning electron microscopy (SEM) showed they displayed a spherical disc-like form, a lenticular shape and an irregular morphology, respectively. Compared with waxy and normal wheat starches, high-amylose wheat starch (HAWS) was characterised by the presence of lower molecular weight amylose fraction, and its granules demonstrated the highest resistance to the cooking. The changes in the IR ratio 1022/999–1047/1022 cm−1 following the gel storage suggested the molecules of HAWS are more readily to re-associate and re-organise into a more organised status than other two starches. The determination of glucose release showed that HAWS had the lowest digestion kinetics (P < 0.001), and this difference in the digestion properties between HAWS and the other two starches might imply that starch molecular structure, in particular amylose structure is another key factor for manipulating starch digestion property rather than amylose content alone.

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