Question

You are given a material that is 20% fat, 8% protein, 5% monosaccharide, 1% ash and the rest water. Based on your knowledge of separation technologies outline an approach you could use to fractionate the first four of these items from the others. Water can be part of the separated streams, but the other three items shouldn’t be present i.e. fat and water but no protein, sugar or minerals should be present. This is to be a commercial scale approach not an analytical lab,                                                                                                 

Answer 1

1. Liquid-Liquid extraction. Fat being soluble in non polar solvent. material is put into a mixture of immiscible polar and nonpolar solvents e.g hexane and water. Fat comes in oraganic phase based upon its solubility in non polar solvent i.e. high partition coeff. Mixture is shaken for few minutes and hexane layer is recovered. Such procedure done two or three times. Recovered hexane are distilled out to recover fat. Water polar solvent retains rest of material i.e. water soluble mono saccharides and proteins.

2. proteins can be separated from mixture by making aggregates with ammonium sulfate which take water out of the protein and hydrophobic domains of protein coalesce and forms aggregates. Extensive aggregation may result in irreversible precipitation of protein distorting the protein 3 D structure (I mean use minimum of ammonium sulfate to cause the effect). Aggregates then centrifuged. Pallets are centrifuged to separate protein from solution. Pallets are resuspended. The solution now contain monosacchrides only.