The preparation and characterisation of a series of chemically modified potato starches

A range of substituted starches has been prepared at moderate temperature (≤90°C) from gelatinised potato starch by treatment in lithium chloride/N,N-dimethylacetamide (DMAC) solution with acyl chlorides. Oleoyl, palmitoyl, lauroyl, capryloyl and butyryl modified starches have been synthesised with degrees of substitution (DS-values) ranging from 0.3 to 3. Characterisation by FT-IR spectroscopy and elemental analysis has confirmed reaction and degree of substitution obtained. DS-Values were controlled by metered addition of stoichiometric quantities of the required acyl chloride. Such structural modification of starch resulted in a significant change of physicochemical properties, and increased hydrophobicity with increasing acylation extent. It was found that the modified starches had improved thermal stabilities and enhanced solubilities in organic solvents.