Applied Biochemistry and Biotechnology, Vol.44, No.1, 49-64, 1994
Kinetics of Ethanol-Production from Carob Pods Extract by Immobilized Saccharomyces-Cerevisiae Cells
Kinetics of ethanol production from carob pods extract by immobilized S. cerevisiae cells in static and shake flask fermentation have been investigated. Shake flask fermentation proved to be a better fermentation system for the production of ethanol than static fermentation. The optimum values of ethanol concentration, ethanol productivity, ethanol yield, and fermentation efficiency were obtained at pH range 3.5-6.5 and temperature between 30-35 degrees C. A maximum ethanol concentration (65 g/L), ethanol productivity (8.3 g/Lh), ethanol yield (0.44 g/g), and fermentation efficiency (95%) was achieved at an initial sugar concentration of 200, 150, 100, and 200 g/L, respectively. The highest values of specific ethanol production rate and specific sugar uptake rate were obtained at pH 6.5, temperature 40 degrees C, and initial sugar concentration of 100 g/L. Other kinetic parameters, biomass concentration, biomass yield, and specific biomass production rate were maximum at pH 5.5, temperature 30 degrees C, and initial sugar concentration 150 g/L. Under the same fermentation conditions nonsterilized carob pod extract gave higher ethanol concentration than sterilized medium. In repeated batch fermentations, the immobilized S. cerevisiae cells in Ca-alginate beads retained their ability to produce ethanol for 5 d.
Keywords:JERUSALEM ARTICHOKE JUICE;ZYMOMONAS-MOBILIS;KLUYVEROMYCES-MARXIANUS;DEPROTEINIZED WHEY;SUGAR EXTRACTION;FERMENTATION;TEMPERATURE;FRAGILIS