Electrospinning of food-grade polysaccharides

A range of polysaccharides of different sources was investigated with respect to their ability to form fibers using electrospinning from aqueous solutions. Polysaccharides were chosen from different sources i.e. from plants, seaweeds and micro-organisms. The polysaccharides derived from plant sources were exudates (galactomannans, glucomannans) and other vegetable sources (e.g. starch, methylcellulose). The polysaccharides from the seaweeds were carrageenans and alginate and the polysaccharides from microbial origin ranged from non-branched (pullulan) to brush-like (e.g. dextran). The polysaccharides could be divided into three categories according to their electrospinning behaviour. The first category was able to form fibers, the second category was able to form a jet but no fibers and the third category (largest, containing all charged polysaccharides tested) was not able to form a jet at all. Possible reasons for a particular type of spinning behaviour are discussed, starting from the characterization of the polysaccharides and their solutions. The intrinsic viscosity, shear viscosity and conductivity were determined for the different polysaccharide solutions. Based on these results, possible relations with electrospinning behaviour are discussed. It was concluded that the overlap concentration and shear thinning properties of the polysaccharides are crucial for successful spinning. Concentrations in the range between 10 and 20 in units of the overlap concentration, probably giving rise to a sufficiently high Trouton ratio, were found to be a necessary condition for spinnability. Equipment settings and conductivity are of secondary importance and merely play a role in optimization of the process.