Fermentation process optimization by response surface methodology for bioethanol production from argane pulp hydrolysate using commercial and laboratory scale isolated Saccharomyces cerevisiae yeast

Abstract

In recent decades, growing attention was devoted to reducing fossil-fuel usage. The production of bioethanol from natural sources is an eco-friendly liquid fuel alternative that can be used in a wide range of applications. In this work, Argane (Argania spinosa (L.) Skeels) pulp hydrolysate was used, for the first time, as a substrate for bioethanol production, aiming to improve the valorization of this local biowaste as a new biomass for biofuel production. Hence, a comparative fermentation study of argane pulp hydrolysate was investigated using commercial and laboratory-scale isolated Saccharomyces cerevisiae Meyen ex EC Hansen yeast (S. cerevisiae). The experiments of the alcoholic fermentation were conducted under the influence of temperature, pH, and yeast concentration on bioethanol yield and sugar consumption using response surface methodology. A maximum bioethanol yield of 5.91 mg/mL was observed under optimal process conditions of 32.5 °C (temperature), 5.5 (pH), and 4.50% of isolated S. cerevisiae. The results showed that isolated S. cerevisiae (Saxapahaw-DS1693) yeast, with a highest yield of 5.91 mg/mL and productivity of 0.098 g/Lh, was more efficient than the commercial S. cerevisiae, with a highest yield of 2.43 mg/mL and productivity of 0.040 g/Lh, during 60 h. Optimization and findings obtained from this study would provide significant knowledge for bioethanol production processes using argane pulp hydrolysate as a new and low-cost option to mitigate the local energy demand.