Industrial potato peel as a feedstock for biobutanol production.

Potato peel from a snack factory was assessed as possible feedstock for biobutanol production. This lignocellulosic biomass was subjected to various physicochemical pretreatments (autohydrolysis and hydrolysis with dilute acids, alkalis, organic solvents or surfactants) under different conditions of time, temperature and reagent concentrations, in order to favour the release of sugars and reduce the generation of fermentation inhibitors. Thereafter, the pretreated potato peel was treated enzymatically to complete the hydrolysis. Autohydrolysis at 140 °C and 56 min was the most effective pretreatment, releasing 37.9 ± 2.99 g/L sugars from an aqueous mixture containing 10% (w/w) potato peel (sugar recovery efficiency 55 ± 13%). The fermentability of the hydrolysates was checked with six strains of Clostridium beijerinckii, C. acetobutylicum, C. saccharobutylicum and C. saccaroperbutylacetonicum. C. saccharobutylicum DSM 13864 produced 2.1 g/L acetone, 7.6 g/L butanol and 0.6 g/L ethanol in 96 h (0.186 g/g), whereas C. saccharoperbutylacetonicum DSM 2152 generated 1.8 g/L acetone, 8.1 g/L butanol and 1.0 g/L ethanol in 120 h (0.203 g/g). Detoxification steps of the hydrolysate before fermentation were not necessary. Potato peel may be an interesting feedstock for biorefineries focused on butanol production.