Inulin fromDahlia spp. tubers (50 g% yield, dry basis; 12.5 g% yield, wet basis) competes with Jerusalem artichoke and chicory as a source of fructose. Mild acid hydrolysis under pH control instead of nominal acid concentration of aqueous orthophosphoric acid resulted in almost quantitative monomerization of the labile fructan backbone. Byproducts hydroxymethylfurfural (HMF), (di)fructose anhydrides (DFA), and oligosaccharides were minimized. Microflora were collected from rottingDahlia, and an inuloytic mold, able to metabolize HMF, as well as bacteria-producing DFA III were recovered. Microbiologically synthesized DFA was tested for biological activity using isolated rat liver perfusion.