The Effect of Different Inoculations and Enzyme-acid Pretreatments on the Bioethanol Production from Two Mediterranean Crops

A combined enzyme-acid hydrolysis of carob pods and aloe pulp, was used, employing pectinase and 0.7% sulphuric acid, respectively. For ethanol fermentation of the obtained hydrolysates, two yeasts were used namely Saccharomyces cerevisiae and Saccharomyces bayanus. The fermentation reactions were monitored by changes in pH over a 720-h period. S. bayanus exhibited superior fermentation potential than S. cerevisiae, with respect to fermentation time (34 h and 185 h) and ethanol yield (9% and 2% v/w), for the carob and aloe respectively. The carob pod fermentation was superior to aloe pulp, however, the effective ethanol yield on large scale plantations, indicate a superior yield by aloe rather than carob, due to the fact that Aloe vera grows faster with a higher plant density as opposed to Ceratonia siliqua.