Comparison of physicochemical properties of starches from seed and rhizome of lotus

Lotus seed and rhizome starches have been used as functional foods in east Asia for thousands of years. In this paper, starches were isolated from lotus seed and rhizome, and their physicochemical properties were compared. Seed starches were small oval granules, rhizome starches had small oval granules and large elongated granules. Seed starches showed significantly higher amylose content and gelatinization temperature and lower swelling power than rhizome starches. Seed starches exhibited an A-type X-ray diffraction pattern with higher crystalline degree, while rhizome starches showed a C-type pattern which changed from C- to A-type with gradually increasing crystalline degree during acid hydrolysis. The degree of order in starch external region was higher in rhizome than in seed. The external region structure of rhizome starches became more ordered during acid hydrolysis. Rhizome starches had higher rate of acid hydrolysis and lower rate of porcine pancreatic α-amylase hydrolysis than seed starches.