Ionic liquids in the selective recovery of fat from composite foodstuffs

BACKGROUND: Ionic liquids (ILs) are able to dissolve a wide range of organic and inorganic molecules and have potential application in the separation and recovery of valuable components from wastes. The potential for ILs to separate sugar and fat from food waste is demonstrated using chocolate as a model system. RESULTS: The ILs 1-(2-cyanoethyl)-3-methylimidazolium bromide (cyanoMIMBr), 1-propyl-3-methylimidazolium bromide (propyIMIMBr), 1-hexylpyridinium bromide (hexyIPyrBr) and 1-butyl-3-methylimidazolium chloride (butyIMIMCI) were synthesised by microwave technology and fully characterised by mass spectrometry, thermogravimetric differential scanning calorimetery, thin layer chromatography, nuclear magnetic resonance and Fourier transform infrared spectroscopy. The solubilities of the fat and carbohydrate components in the ILs are reported for the two main ingredients in chocolate. CyanoMIMBr and propyIMIMBr selectively solubilise sugar leaving the fat insoluble. Both cyanoMIMBr and propyIMIMBr have been used to successfully separate sugars and cocoa butter fat from white, milk and dark chocolate and the Fourier transform infrared spectra and thermogravimetric differential scanning calorimeter profiles of the extracted fat samples are in good agreement with reference material data. CONCLUSIONS: The ILs cyanoMIMBr and propyIMIMBr are successful in the separation and recovery of fat from white, milk and dark chocolate, as confirmed by FTIR and TG-DSC data. (C) 2009 Society of Chemical Industry