Bioethanol Production from Corn Meal Hydrolyzates by Immobilized Saccharomyces cerevisiae var. ellipsoideus

Abstract

Bioethanol can be produced by fermentation of sugars from waste agricultural materials. In this process immobilized yeast offer advantage over free cell suspension with regard to ethanol productivity, fermentation rate and product inhibition. The aim of the present study was to investigate the immobilization of Sacharomyces cerevisiae var. ellipsoideus yeast cells for bioethanol production from corn meal hydrolyzates. For this purpose the biocompatible polymers such as: PVA and Ca-alginate were assessed. The conditions of ethanol fermentation, such as inoculum concentration in different carriers, fermentation rate and the choice of a convenient carrier for the efficient ethanol production were studied, The maximum ethanol concentration of 10.05% (w/w) was obtained in the fermentation of corn meal hydrolyzates by 5% (v/v) inoculum concentration of the yeast immobilized in Ca-alginate using a method of electrostatic droplet generation. The repeated batch fermentation with the yeast immobilized in Ca-alginate at an initial sugar concentration of 176g/l, indicated that alginate gels degraded after the second fermentation cycle and 76 hours. In contrast, PVA carrier exhibited better mechanical properties and stability, however lower ethanol concentrations were achieved during the fermentation.