Preparation of water‐soluble starch oligomers from variable starch species in 1‐allyl‐3‐methylimidazolium chloride

Native wheat, barley, rice, maize, wx maize, and potato starch species were modified by depolymerization in 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) ionic liquid (IL) using oil bath or microwave heating. Reactions were catalyzed with p-toluenesulfonic acid (p-TsOH). Reaction times varied depending on the starch species and its concentration, the heating method, and volume of the reaction mixture. Depolymerization products were analyzed with HPLC-ELSD. All starch species mostly degraded into water-soluble 1500–2000 Da-sized starch oligomers. Glucose and other short-chained sugars did not precipitate along with starch oligomers due to their high solubility in IL. This property was utilized in the purification of commercial maltodextrins. Produced water-soluble, low MW starch oligomers might be used, e.g., in bacterial cultivations as a glucose source.