use of xanthan gum in tomato ketchup
Xanthan gum is a polysaccahride obtained through a fermentation process.  It is used to greatly reduce syneresis, stabilize emulsions, and to keep particles suspended in mixtures. It is "shear thinning", meaning that liquids with xanthan are viscous when at rest, but fluid when stirring. It has other culinary uses as well, but would be a good experiment your ketchup application.  You will want to add in a concentration of 0.7 - 1.5% of your total batch.  Be careful of using in a higher concentration, as xanthan can impart an undesirable, mucous-like texture if used too heavily.  

Credit to Martin Lersch, and his terrific pdf called "Texture: A Hydrocolloid Recipe Collection."