Prospective Production of Fructose and Ethanol for Food and Fuel Markets by Selective Fermentation of Date Syrups

Abstract

Sugars (fructose and glucose) in dates constitute about 75% of its dry weight. The effect of temperature and agitation on the production of fructose and ethanol from date syrups through selective fermentation of date syrups using S. cerevisiae ATCC 36858 was investigated in small-scale shake flask reactors. The ethanol production decreased with temperature due to the augmented inhibitory effect of ethanol at higher temperatures. The best temperature for cell growth was 33 C. At agitation speed of 160 rpm, ethanol productivity and specific growth were 0.97 g h-1 L-1 and 0.041 h-1, respectively, at 30 C. Fructose fractions produced here (>90%) were much higher than the commercial ones (42% and 55%); thus rendering the production of fructose from dates an economically viable process. The predictive character of Gompertz equation for ethanol production was extended by incorporating the temperature dependence of the parameters into the equation. Excellent fit was obtained with the extended equation in 27 C to 35 C.