| Cane molasses is high in sugar and contains a lot of nutrient substance that yeast needs to grow,but it has complex components which inhibit the growth and propagation and fermentation,such as the colloidal substances,metal ions and caramel pigment,etc.So the alcoholic fermentation of cane molasses has various problems,such as high residual sugar,long fermentation time,low sugar consumption rate,low ethanol productivity,low concentration of ethanol,low fermentation efficiency,etc.Therefore,take some methods to remove or reduce the materials that are harmful to the growth of yeast cells,such as colloid and metal ions in cane molasses medium,and it is very important to improve the cell viability,sugar utilization rate and ethanol productivity of yeast in the fermentation process of cane molasses.In this experiment,cane molasses was pretreated by different methods before fermentation,study the conditions of the alcoholic fermentation of cane molasses that treated with different pretreatment methods.It provides some reference for its industrial production.The research contents are as follows:(1)Different dilution ratio of sugar cane molasses ethanol fermentation experimentsWith sugar cane molasses: water according to 1:1,1:1.5,1:2 and 1:3,dilute 1:5 scale configuration sugarcane molasses ethanol fermentation medium,at 32 ?and the revolving speed is 12r/min.Results are as follows: The cane molasses medium which the initial total sugar concentration was 100g/L,yeast cell fermentation time was the shortest,the amount of residual sugar was the least,and the yield of ethanol productivity was high.However,the fermentation time is short,the concentration of ethanol production at the end of fermentation is lower;When the initial total sugar concentration was 300g/L,its residual sugar was the highest,the fermentation time was the longest and the alcohol level was not high.This result is due to the high concentration of harmful substances that inhibiting yeast growth in sugarcane molasses.(2)Effects of osmotic pressure and exogenous ethanol concentration on yeast ethanol fermentationTotal sugar content(g/L): 180,220,260,300,340,Na Cl(g/L)was added: YEPD fermentation medium of 0,10,30,50,70,90 and YEPD fermentation medium with different concentration of anhydrous ethanol(g/L): 0,10,30,50,70 and 90 by studying its OD value and sugar consumption situation,analyzed the influence of the osmotic pressure of yeast fermentation.Found not add Na Cl YEPD in fermentation process,its sugar consumption rate is the fastest,fermentation time the shortest,most OD the highest value,and with the increase of the concentration of Na Cl,result in higher osmotic pressure of fermentation medium,thereby extended the fermentation time,reduced the sugar consumption rate,reduce the growth of yeast cells reproductive capacity and maximum OD value reduced.The fermentation medium of osmotic pressure on the growth of yeast cells and sugar consumption has a certain inhibitory effect.Found that when the concentration of total sugar is higher than 260 g/L,with the increase of sugar concentration on the growth of yeast and sugar use all has certain inhibitory effect,but in the early when the concentration of 300 g/L of total sugar,sugar from sugar cane molasses fermentation process and is not the main factors inhibiting the growth of yeast and sugar consumption.(3)Ethanol fermentation test of sugarcane molasses pretreatmentThis experiment pretreated cane molasses by boiling,calcium phosphate,potassium ferrocyanide,combined treatment and other methods.To study the effect of GJ2008 on ethanol concentration in cane molasses fermentation.It provides a theoretical basis for the alcoholic fermentation of sugarcane molasses.Results are as follow: The concentration of ethanol after without treatment,boiling treatment,activated carbon,calcium phosphate,potassium ferrocyanide treatment,acid treatment and combined treatment were 82.45 g/L,64.00 g/L,85.21 g/L,84.82 g/L,84.03 g/L,95.47 g/L,100.60 g/L respectively.Compared with the untreated(control group),there was no significant change in fermentation time during the fermentation of cane molasses.However,the concentration of residual sugar decreased,the concentration of ethanol increased,and the rate of sugar consumption and ethanol production increased;Compared with the untreated(control group),the combined treatment group with the best effect whose total residual sugar decreased by 52.6%,final ethanol concentration increased by 22.01%,and ethanol productivity increased by 21.89%.Results show that after pretreatment of sugar cane molasses medium is more conducive to the growth of yeast breeding and fermentation,increase the ability of yeast cells to use sugar,increase the sugar consumption rate,ethanol productivity and fermentation efficiency of yeast.Increased the final ethanol concentration at the end of fermentation.(4)Sugarcane molasses combined treatment of 5L canisters ethanol fermentation testStudied the alcoholic fermentation of cane molasses medium pretreated by combined treatment in 5 L tank,at 32 ?,continuous ventilation(ventilation of 80 ml/min),natural p H,and the stirring speed is 200 r/min.The results are as follows: fermentation time is 72 h,the final ethanol concentration is 99.02 g/L,ethanol productivity is 1.38 g/(L·h),the concentration of residual sugar was 33.2g/L,total sugar fermentation efficiency was 72.6%,sugar consumption rate was 82.9%.Compared with cane molasses pretreatment of conical flask batch ethanol fermentation,the fermentation time increased by 6h.The final ethanol concentration,the rate of ethanol production,the total sugar fermentation efficiency,and the sugar consumption of fermentation were all slightly decreased,but the decrease was not significant. |
PDF Full Text Request