Biofuel Potentiality of Pineapple Peelings in the Presence of the Yeasts Saccharomyces cerevisiae and Saccharomyces carlsbergensis

Abstract

In pineapple industries and processing units, peelings constitute waste piled up in landfills and therefore cause real problems for environment. The present study aims to develop this available and neglected bioresource, through the study of the kinetics of its conversion into bioethanol by fermentation with a view to its use as a biofuel. To do this, the pineapple peelings juice was converted into bioethanol by fermentation in the presence of the yeasts: S. cerevisiae and S. carlsbergensis. Monitoring of fermentation kinetic parameters such as Brix degree, pH, titratable acidity and density, shows a great variability of these parameters during the fermentation process in bioreactors. The distillation of the musts at the end of fermentation made it possible to obtain ethanol levels (% v/v at 20°C) between (2.77 ± 0.03%) and (28.69 ± 0.03%). The best ethanolic bioconversion performance was recorded with the yeast S. carlsbergensis on the must enriched with urea (CON2H4) followed by the strain (S3) of the yeast S. cerevisiae. Analysis of the results shows that the alcoholic degrees of the different distillates depend on the type of microorganism as well as whether or not growth factor added to the fermentation musts. It appears that the addition of a selected strain especially in the presence of growth factor promotes the kinetics of the alcoholic fermentation process, thus leading to a better yield of ethanol production. Production of ethanol from agricultural and biodegradable waste would also provide a viable solution to environmental problems creating a sink for waste and renewable energy production as well.