Use of room temperature ionic liquids for the selective fractionation of bioactive ketoses from aldoses

•ILs are a useful and green alternative for fractionation of ketoses from aldoses.•BMIM[meso4] is useful for the selective fractionation of tagatose from galactose.•EMIM[DCA] is useful for the enrichment of lactulose in its product of synthesis.•Carbohydrates are effectively extracted from ILs by an activated charcoal method.

This work deals with the effective fractionation of bioactive ketoses, i.e. lactulose and tagatose, from their corresponding aldoses, lactose and galactose, in equimolar binary mixtures driven by room temperature ionic liquids, i.e. 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA]) and 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][MeSO4]), respectively. Under assayed conditions, tagatose was found to be 6-fold more soluble on [BMIM][MeSO4] than galactose; meanwhile lactulose was 3 times more soluble than lactose on [EMIM][DCA]. As an application example in a more complex sample, a lactose isomerization mixture containing in addition lactulose and monosaccharides was enriched in this ketose by using [EMIM][DCA]. Carbohydrates were then successfully recovered from the ionic liquid following an activated charcoal-based treatment. Overall, lactulose content was enriched from a 24% in the initial isomerization reaction mixture to a 62% in the purified sample. These experimental results demonstrated the potential of ionic liquids as green alternative solvents for the selective fractionation of bioactive ketoses from their corresponding aldoses in food and beverage production.

Graphical abstractEffective fractionation of ketoses from aldoses using ionic liquids and subsequent extraction with active charcoal treatment.Figure optionsDownload full-size imageDownload as PowerPoint slide