an investigation and modeling of sugar reduction, bioethanol and carbon dioxide production during fermentation of date fruits

date fruit, containing a substantial amount of carbohydrates is considered as an important agricultural product in iran. in this research, the objective was the use date fruit wastes to produce bioethanol. for better understanding of the fermentation process the changes in sugar content, as well as the amount of produced bioethanol and carbon dioxide were periodically measured and modeled while using different mathematical models. to conduct the experiments, water was added to date syrup with 75°bx to be diluted to 20°bx. for proper initiation of fermentation, s.cereviea inoculums along with different nutritional compounds were added to the syrup. the fermentation was done at 30±1°c. results indicated that the rate of changes had an increasing trend during the first 5 days of the process, while decreasing sharply for the next following 15 days. at the end of the process, the brix of the syrup dropped to near 8.0°bx. the bioethanol resulted from fermentation of the syrup was 72 g per liter. the produced carbon dioxide was figured out as 70 ml/l. a comparison of the applied models indicated that all the investigated models fitted well to the experimental data, but the decaying exponential model with an r2 =0.99 was the most fitted for sugar reduction modeling while the gompertz model (r2 > 0.98) was found out as the most suitable the best for bioethanol and carbon dioxide production.