T. Roukas, KINETICS OF ETHANOL-PRODUCTION FROM CAROB PODS EXTRACT BY IMMOBILIZEDSACCHAROMYCES-CEREVISIAE CELLS, Applied biochemistry and biotechnology, 44(1), 1994, pp. 49-64
Kinetics of ethanol production from carob pods extract by immobilized
S. cerevisiae cells in static and shake flask fermentation have been i
nvestigated. Shake flask fermentation proved to be a better fermentati
on 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 concentrati
on (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 c
oncentration of 200, 150, 100, and 200 g/L, respectively. The highest
values of specific ethanol production rate and specific sugar uptake r
ate were obtained at pH 6.5, temperature 40 degrees C, and initial sug
ar concentration of 100 g/L. Other kinetic parameters, biomass concent
ration, biomass yield, and specific biomass production rate were maxim
um at pH 5.5, temperature 30 degrees C, and initial sugar concentratio
n 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 i
n Ca-alginate beads retained their ability to produce ethanol for 5 d.