Thermal Hydrolysis of Orange Peel and its Fermentation with Alginate Beads to Produce Ethanol

Orange peel (OP) was subjected to thermal hydrolysis at temperature (T) and pressure (P) values lower than 180 °C and 1000 kPa, respectively, to minimize the energy consumption and obtain a good ethanol yield. The process was conducted in an autoclave, a pressurized reactor for studying the effect of T (120 to 180 °C), P (500 to 1000 kPa), gas type (N2 or CO2), and OP loading (2.5 x10-2 and 5 x10-2 gmL-1) on the reducing sugars yield. The results were compared with those from acid hydrolysis. Hydrolysates were fermented using immobilized yeast on alginate beads, and the highest ethanol yield of 33.14 g/L was obtained from OP treated at 120 °C. Under these conditions, a minimum of 1,407 kWh energy consumption was achieved.