Structures and properties of selenylated starch granules prepared using a novel method

Polysaccharides were the promising candidates for the development of selenium-enriched health-promoting foods. However, there was a lack of information regarding the synthesis of selenylated starch granules using straightforward methods and the impact of selenium decoration on starch properties. This study introduced a process for creating selenylated starch granules by heating a water-limited ethanol solution containing starch granules, acetic acid, and selenic acid. The results demonstrated that selenylated starch granules could be synthesized by introducing selenium to the hydroxyl groups on the starch chains. The selenylated starch granules produced through this method retained the same morphology as native starch but exhibited a smaller molar mass, less ordered structures, increased solubility, significantly lower viscosity, and reduced digestibility. Compared to selenylated starch synthesized in water, starch modified in the water-ethanol system yielded more intact granules, achieved a higher yield (91.9 % versus 88.0 %), contained more selenium (1.3 mg/g starch versus 0.9 mg/g starch), and displayed more ordered structures (including helical, crystalline, and lamellar structures). Additionally, these granules showed higher viscosity, lower solubility, and reduced digestibility. These findings paved the way for a promising approach to synthesize selenylated starch granules.