Structural and functional properties of endosperm starch and flour from dicotyledon Mirabilis jalapa

摘要

The large endosperm of dicotyledon Mirabilis jalapa may have food and non-food industrial applications because of its high starch content. In this study, the structural and functional properties of endosperm starch and flour from M. jalapa were investigated. Each seed (about 170.8mg fresh weight) contained approximately 37.3mg of dry endosperm. The endosperm contained about 80.1% starch, 1.5% soluble sugar, and 2.3% protein. Starch granules were small (about 1.5 mu m) with a regular spherical shape. The starch contained about 56.5% short branch-chain of amylopectin, 21.3% long branch-chain of amylopectin, and 22.2% amylose. The starch and flour had C-A-type crystallinity, while the swelling power and water solubility of starch were 15.8g/g and 17.1%, respectively. The starch had lower gelatinization temperature and higher pasting viscosity than flour. No peak and hot viscosity was observed in pasting profiles of starch and flour. The flour had higher resistance to acid and amylase hydrolysis than starch. Native, gelatinized and retrograded starches had about 16.3%, 86.6%, and 76.6% of rapidly digestible starch, and 46.5%, 2.4%, and 11.8% of resistant starch, respectively. These results were compared with those obtained from monocotyledon rice endosperm starch and flour.