Improving downstream processes to recover tartaric acid, tartrate and nutrients from vinasses and formulation of inexpensive fermentative broths for xylitol production.

ABSTRACT

BACKGROUND: Vinasses, the main liquid wastes from the distillation process of grape marc and wine lees, are acidic effluents with high organic content, including acids, carbohydrates, phenols, and unsaturated compounds with high chemical oxygen demand, biological oxygen demand and solid concentrations. These wastes can be revalued to provide additional benefits when they are employed as feedstock of some compounds including tartaric acid, calcium tartrate and economic nutrients for the elaboration of fermentable broths. RESULT: This study attempts to recover tartaric acid and calcium tartrate from vinasses. All the tartaric acid initially solubilised was recovered in both processes. The residual streams can be successfully employed as economic nutrients for the xylose to xylitol bioconversion, achieving higher global volumetric productivities (Q(P, xylitol) = 0.232 g L(-1) h(-1)) and products yields (Y(xylitol/S) = 0.57 g g(-1)) than fermentations carried out using commercial nutrients (Q(P, xylitol) = 0.193 g L(-1) h(-1) and Y(xylitol/S) = 0.55 g g(-1) respectively). CONCLUSION: Tartaric acid can be recovered from vinasses in the form of tartaric acid crystals and calcium tartrate. The residual streams generated in the process can be used as economic nutrients for the production of xylitol by D. hansenii.