Understanding the multi-scale structure and digestion rate of water chestnut starch

Using combined techniques and two comparisons (maize and cassava starches), this work concerns the multi-scale structure and digestion rate of water chestnut tuber starch. Among the starches, the water chestnut starch showed altered hierarchical structural features and a relatively low digestion rate. The underlying mechanism on the reduced digestion rate of water chestnut starch was discussed from a hierarchical structural view. Specifically, compared with maize starch, the water chestnut starch contained no pores on the granule surface, with the thickened crystalline lamellae, the increased lamella ordering, and the elevated content of crystallites. Such structural features probably increased the bulk density of molecule assembly in starch and thus could hinder the diffusion of enzyme molecules in starch matrixes. Consequently, the absorption of enzyme to the starch glucan chains could be retarded, resulting in a reduced enzyme hydrolysis rate of starch chains. The relatively large amylose molecules of water chestnut starch also tended to reduce the starch digestion rate, associated with the enhanced molecule interactions such as that between starch chains. In addition, the further reduction in the digestion rate of cassava starch could be also ascribed to the variations in the multi-scale structural features.