Biotechnological Valorization of Orange Processing Waste Into Bioethanol: Physicochemical Characterization and Fermentation Performance

This study investigates the physicochemical characteristics of two local varieties of orange processing waste to assess their potential as biofuel feedstocks. The raw material was pretreated in an autoclave using steam explosion and dilute acid hydrolysis at 121°C and 1 bar, with 0.5% sulfuric acid and a 2% substrate concentration for 20 min. Fermentation was carried out with Saccharomyces cerevisiae under anaerobic conditions. The highest total sugar content was observed in the Valencia Late variety (49.33% ± 0.78% dry weight), compared to 44.04% ± 1.32% for Double Fine. Distillate volumes were 25 mL for Valencia Late and 27 mL for Double Fine, corresponding to ethanol yields of 5.0% (v/v) and 5.4% (v/v), respectively. Furthermore, gas chromatography analysis of the ethanol indicated retention times of 1.379 and 1.385 for Valencia and Double Fine, respectively, closely aligning with the standard retention time of 1.380. These findings demonstrate that orange peel lignocellulosic biomass presents a promising source for the production of second‐generation bioethanol.