An Integrated Fermentation-Ultrafiltration Process for the Production of Xanthan Gum from Whey Lactose

The goal of this project is to develop an integrated fermentation-ultrafiltration process for economical production of xanthan gum from glucose and galactose present in a waste sugar stream from a galacto-oligosaccharides (GOS) production process. There are -80 billion lbs of cheese whey generated annually in the dairy industry and much of this byproduct has no economical use at the present time and requires costly disposal because of its high biological oxygen demand. We have developed an immobilized enzyme process to produce GOS from whey lactose. GOS is a prebiotic with wide applications in human and animal foods. However, glucose and galactose are also produced in the process and must be removed from GOS because these monosaccharides do not have and can reduce the prebiotic effect. Xanthan gum is a microbial polysaccharide widely used as a suspending, stabilizing, and thickening agent in food and oil-recovery industries. In this project, we will develop a novel, rotating fibrous bed bioreactor (RFBB) for cell immobilization and fermentation to produce cell-free xanthan gum broth that can be readily concentrated and purified by ultrafiltration. The RFBB can overcome mixing and aeration problems commonly associated with viscous fermentation when carried out in conventional stirred tank bioreactors. The RFBB can double the reactor productivity and reach a high xanthan gum concentration of more than 70 g/L (vs. less than 30 g/L). The effects of process conditions on the final xanthan gum properties (viscosity, molecular weight, etc.) will be studied to evaluate the feasibility of producing xanthan gum from glucose and galactose.