Bioethanol production from Jerusalem artichoke by acid hydrolysis

The hydrolysis of inulin from Jerusalem artichoke (JA) slices by HCl under different regimes of temperature and hold (contact time) time was investigated. Final reducing sugars concentration in the hydrolyzates depended on temperature, pH, hydromodule (JA:water) and hold time. Acid hydrolysis at higher temperature and longer hold time increased the degradation of fructan to fructose and increased the concentrations of inhibitory compounds such as 5-hydroxymethylfurfural (HMF). Acid hydrolysis at 126 C, hydromodule 1:1 and pH 2, resulted in less than 0.2 g/L HMF at both hold times (30 min and 60 min.). Fermentation of the hydrolyzates obtained by hydrolysis at 126 C, hydromodule 1:1, pH 2 and hold time 60 min, resulted in the highest ethanol yield of 7.6 % w/w, which corresponds to volumetric productivity of ethanol 1.52 g /Lh and 94.12 % (w/w) of theoretical yield of ethanol.