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Comparison of physicochemical pretreatments of banana peels for bioethanol production

Palacios, Sócrates, Ruiz, Héctor A., Ramos-Gonzalez, Rodolfo, Martínez, José, Segura, Elda, Aguilar, Miguel, Aguilera, Antonio, Michelena, Georgina, Aguilar, Cristóbal, Ilyina, Anna
Food science and biotechnology 2017 v.26 no.4 pp. 993-1001
Kluyveromyces marxianus, autoclaves, autoclaving, banana peels, cellulose, enzymatic hydrolysis, ethanol, ethanol production, fermentation, grinding, hemicellulose, hydrolysis, lignin, reducing sugars, sugar content, sulfuric acid, temperature
Pretreatments with different concentrations of sulfuric acid (0, 0.5, and 1% v/v) and temperatures (28 and 121 °C at 103 kPa in an autoclave) were performed on banana peels (BP) milled by mechanical grinding and grinding in a blender as well as without grinding. Cellulose, hemicellulose, lignin, ash, and total and reducing sugar contents were evaluated. The highest yields of cellulose enzymatic hydrolysis (99%) were achieved with liquefied autoclaved BP treated with 0.5 and 1% acid after 48 h of hydrolysis. Ethanol production by Kluyveromyces marxianus fermentation was assayed using hydrolyzed BP at 10, 15, and 20% (w/w). The highest ethanol level (21 g/L) was reached after 24 h of fermentation with 20% (w/w) BP. Kinetics of the consumption of reducing sugars under this fermentation condition demonstrates the presence of a lag period (about 8 h). Thus, BP are a good source for ethanol production.