Studies On Process And Kinetics Of Ethanol Batch Fermentation With Different Concentrations Of Sucrose

Microbial fermentation is a process of dynamic change,in order to find the main rule of cane sugar ethanol fermentation process,in this paper,Phloxine B was established to detect the activity of yeast cells and the dynamic method,and then apply it to different concentrations of sucrose in the process of ethanol fermentation,explore law of fermentation process and the corresponding fermentation kinetics equation,the main results are as follows:(1)When the concentration of dye was 10?g/m L,the contact time was 5min,and the contact temperature was 25?,the OD value of yeast cell diluent measured by Phloxine B method was in the range of 0.24-0.952,which was close to that of Methylene blue method.It indicated that Phloxine B method could identify the dead or alive yeast cells,and simultaneously determine the total number of dead and alive yeast cells.The visible light scanning of Phloxine B showed that it had the maximum absorption peak at 535 nm,and the amount of dye adsorbed by cell Phloxine B showed a linear relationship with the number of cells at this wavelength.The more the number of dead cells,the greater the amount of dye adsorbed by cell Phloxine B,the smaller the relative vitality.In the ethanol batch fermentation with 200 g/L glucose,the relative activity increased first and then decreased,and reached the highest value at 12 h.The fermentation broth at five time points at 8 h,10 h,12 h,14 h and 16 h was supplemented with 100 g/L glucose at one time for batch fermentation.It was found that the yeast cell vitality at 12 h was the highest,the ethanol output was 142.02g/L at most,and the fermentation efficiency was 89.99 % at most.(2)In the batch fermentation of ethanol with different concentrations of(180,220,260,300,340)g/L sucrose,the rapid growth period of yeast was 0 h-9 h.The maintenance time of yeast growth after entering the stable stage was shortened with the increase of the initial sucrose concentration,and the cell viability was delayed with the increase of the initial sucrose concentration.Ethanol generates trend is roughly same,in sucrose concentration is less than260 g/L,the ethanol production after 3h increase quickly,and when the sucrose concentration of 260 g/L or higher,a rapidly increasing ethanol production time is after 6h,and five experiments of maximum ethanol generation rate highest had occurred in the cell vitality,and high concentration of sugar in the fermentation process has quite part of total sugar to grow in the yeast stabilization into ethanol.The five groups of sucrose with different concentrations hydrolyzed almost completely(100 %-99.94 %)in the fermentation process.Before 15 h,the sucrose with different concentrations in each group belonged to the rapid hydrolysis stage,and the maximum hydrolysis rate did not change greatly.Glucose utilization(99.81 %-90.04 %)is always greater than the utilization rate of fructose(91.41 %-62.18 %),the total sugar consumption is increasing in real terms,but utilization is decreasing.In conclusion,in the fermentation process of low concentration sucrose ethanol,yeast cells maintained high vitality for a long time,sucrose hydrolysis,total sugar consumption and ethanol generation mainly occurred in the rapid growth phase of cells,and high vitality cells helped to reduce the difference in fructose and glucose utilization.In the high-concentration sucrose fermentation,the vitality of cells was low and delayed,and the maintenance time was short.The ethanol generation mainly occurred after the rapid growth period,and the increase of ethanol concentration at the end was small,the actual total sugar consumption was reduced,the utilization difference of glucose and fructose in cells was large,and the amount of residual fructose was increased,leading to the decrease of fermentation efficiency.Finally,the total sugar fermentation efficiency of the five groups with sucrose concentration was85.89±2.33 %,88.57±1.31 %,77.06±1.17 %,70.25±2.30 % and 64.06±0.71 %,respectively.(3)The Logistic equation and the Luedeking-Piret-like equation were used to establish the kinetic model of yeast growth,ethanol production and total sugar consumption during the batch fermentation of ethanol with different concentrations of(180,220,260,300,340)g/L sucrose.and the equations were inferred through mathematical calculations and fitted to the experimental data non-linearly using software.The fitting degree between the predicted value of the model and the true value of the experiment is mostly > 0.99,The results were good and the kinetic equations proved to be reliable.