The acid hydrolysis of potato tuber mash in bioethanol production

The hydrolysis of starch from fresh potato tubers by HCl and H2SO4 at different ratios of plant material to acid solution was investigated. The final reducing sugars concentration in the hydrolyzates depended on the type and concentration of acid and the ratio of plant material to acid solution but not on the type of potato. The highest dextrose equivalent of 94%, the greatest reaction rate constant of 0.089 min−1 and the 5-hydroxymethylfurfural (5-HMF) yield of 0.04 g/L were achieved using 1 M HCl at the ratio of plant material to acid solution of 1:2 (w/v). The ethanol yield of 31 g/L was obtained in the fermentation of hydrolyzate prepared under the optimal hydrolysis conditions by commercial bakery yeast at 28 °C for about 18 h.