Study of the production of fructose and ethanol from sucrose media by Saccharomyces cerevisiae

The production of ethanol and enriched fructose syrups from a synthetic med ium with various sucrose concentrations using the mutant Saccharomyces cere visiae ATCC 36858 was investigated. In batch tests, fructose yields were ab ove 90% of theoretical values for the sucrose concentrations between 35 g/l and 257 g/l. The specific growth rates and biomass yields were from 0.218 to 0.128 h(-1) and from 0.160 to 0.075 g biomass/g of glucose and fructose consumed, respectively. Ethanol yields were in the range of 72 to 85% of th eoretical value when sucrose concentrations were above 81 g/l. The volumetr ic ethanol productivity was 2.23 g ethanol/(I h) in a medium containing 216 g/l sucrose. Fructo-oligosaccharides and glycerol were also produced in th e process. A maximum fructo-oligosaccharides concentration (up to 9 g/l) wa s attained in the 257 g/l sucrose medium in the first 7 h of the fermentati on. These sugars started to be consumed when the concentrations of sucrose in the media were less than 30% of its initial values. The fructo-oligosacc harides mixture was composed of 6-kestose (61.5%), neokestose (29.7%) and 1 -kestose (8.8%). The concentration of glycerol produced in the process was less than 9 g/l. These results will be useful in the production of enriched fructose syrups and ethanol using sucrose-based raw materials.