HPLC-ELSD analysis of six starch species heat-dispersed in [BMIM]Cl ionic liquid

Acid hydrolysis of starch is a commonly used modification that reduces the molecular size and produces soluble starch. The thermal treatment of starch in 1-butyl-3-methylimidazolium chloride, [BMIM]Cl, ionic liquid (IL) provides an alternative method for that. Six native starches (wheat, barley, potato, rice, corn and waxy corn) were heat-dispersed under controlled microwave conditions or in oil bath into [BMIM]Cl. Starches and their degradation products were studied by using a HPLC-ELSD. ELS detector is a universal and response independent detector which after optimization produced a good response to small and large carbohydrates. However, it has rarely been applied to starch analysis. During heating in [BMIM]Cl components of native starches, amylopectin and amylose, started to degrade. The increasing reaction temperature and time intensified the degradation. The use of microwave heating speeded up dissolution and degradation of starch compared to the conventional heating. A separate acid catalyst was not required.