(551c) Production of Lignin Microparticles

The initial motivation for this work was the potential use of microparticulated lignin as a structuring agent that would promote stability in processed foods, when sugar, fat or salt are removed in response to growing concerns over their presence in food products. Organosolv processing was used to extract lignin from shrub willow, utilising ethanol as a food-grade solvent. Microparticles were prepared using an anti-solvent precipitation technique, in which the aqueous-organic solution of lignin obtained by organosolv extraction was gently mixed into an aqueous solution. Particle formation occurred via the partitioning of solvent ethanol into the aqueous phase and subsequent precipitation of lignin. In the absence of added surfactants, the temperature of precipitation had a large impact on particle size; increasing temperature caused sub-micron primary particles to agglomerate and fuse into monolithic masses. However, incorporating the ionic surfactants sodium dodecyl sulfate or cetyltrimethylammonium bromide in the aqueous phase at concentrations < 1 wt% produced spherical, monodisperse lignin particles in the range 0.1 – 0.2 μm. The size of surfactant-stabilised particles was also dependent on ionic strength. This presentation will outline available approaches for manipulating particle size and producing microparticles suitable for use in a range of food systems.