Valorization of Potato Peelings in the Production of Bioethanol by Fermentation: Optimization of Pretreatment, Liquefaction and Saccharification

This work aims to produce bioethanol from the starch of fresh potato peelings. The process goes through thermal pre-treatment followed by grinding then enzymatic liquefaction by alpha amylase, saccharification by glucoamylase and finally by fermentation using Saccharomyces cerevisiae. The results show that optimal conditions of the thermal pre-treatment were 130°C for 15min. While enzymatic liquefaction by alpha-amylase was conducted at pH6, under 55°C during 2 hours and un ratio of 18 CEIP/g of fresh potato peelings. Optimal conditions of saccharification were determined as a duration of 3 h, at pH4, and T°=50°C for an average ratio of 0,06 g-glucoamylase/g of liquefied fresh potato peelings, which resulted in a yield of (90%-99%). A maximum bioethanol concentration of 86g/l was obtained by fermentation which correspond to a real yield of 43g of bioethanol (55 mL) /Kg of fresh potato peelings.