The Production of Bioethanol from Carob Pods (Ceratonia siliqua L.)

Abstract

This study seeks to investigate the use of carob (Ceratonia siliqua. L) as a potential source of bioethanol production. In addition, an attempt to optimize the method through sulfuric acid hydrolysis was carried out and the optimum pH range for carob fermentation was studied at pH 2.5, 4.5 and 7.5. Samples of both foreign and locally originating carob were used and any discrepancy in fermentation performance with respect to origin was noted. Each fermentation setup was prepared with 66 gL-1 carob powder, inoculated with 1gL-1 Saccharomyces cerevisiae yeast strain and supplemented with 0.6 mgL-1 thiamine hydrochloride. A total of 36 fermentation broth samples taken at 24-hour time intervals were analysed for different fermentation variables to monitor the progression of fermentation. Changes in total acidity and reducing sugar were analysed through titration techniques and pH. A quantitative sugar profile based on fructose, glucose and sucrose was constructed using an in-house validated method by HPLC-Refractive Index detector. Ethanolic content of the fermentation broth was determined through an in-house validated method by HPLC-UV detector. A significant change (p < 0.05) in ethanol content across time, was detected, with the highest ethanol concentration being achieved in the unhydrolysed control sample with 1.19% v/v from 66gL-1 carob powder.