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1.
Pretreatment of corn stover using wet oxidation to enhance enzymatic digestibility 总被引:17,自引:0,他引:17
Corn stover is an abundant, promising raw material for fuel ethanol production. Although it has a high cellulose content,
without pretreatment it resists enzymatic hydrolysis, like most lignocellulosic materials. Wet oxidation (water, oxygen, mild
alkali or acid, elevated temperature and pressure) was investigated to enhance the enzymatic digestibility of corn stover.
Six different combinations of reaction temperature, time, and pH were applied. The best conditions (60g/L of corn stover,
195°C, 15 min, 12 bar O2, 2 g/L of Na2CO3) increased the enzymatic conversion of corn stover four times, compared to untreated material. Under these conditions 60%
of hemicellulose and 30% of lignin were solubilized, whereas 90% of cellulose remained in the solid fraction. After 24-h hydrolysis
at 50°C using 25 filter paper units (FPU)/g of dry matter (DM) biomass, the achieved conversion of cellulose to glucose was
about 85%. Decreasing the hydrolysis temperature to 40°C increased hydrolysis time from 24 to 72 h. Decreasing the enzyme
loading to 5 FPU/g of DM biomass slightly decreased the enzymatic conversion from 83.4 to 71%. Thus, enzyme loading can be
reduced without significantly affecting the efficiency of hydrolysis, an important economical aspect. 相似文献
2.
Corn stover, the most abundant agricultural residue in Hungary, is a potential raw material for the production of fuel ethanol
as a result of its high content of carbohydrates, but a pretreatment is required for its efficient hydrolysis. In this article,
we describe the results using various chemicals such as dilute H2SO4, HCl, and NaOH separately as well as consecutively under relative mild conditions (120°C, 1h). Pretreatment with 5% H2SO4 or 5% HCl solubilized 85% of the hemicellulose fraction, but the enzymatic conversion of pretreated materials increased only
two times compared to the untreated corn stover. Applying acidic pretreatment following a 1-d soaking in base achieved enzymatic
conversion that was nearly the theoretical maximum (95.7%). Pretreatment with 10% NaOH decreased the lignin fraction >95%,
increased the enzymatic conversion more than four times, and gave a 79.4% enzymatic conversion. However, by increasing the
reaction time, the enzymatic degradability could also be increased significantly, using a less concentrated base. When the
time of pretreatment was increased three times (0.5% NaOH at 120°C), the amount of total released sugars was 47.9 g from 100
g (dry matter) of untreated corn stover. 相似文献
3.
Enhancing the Enzymatic Hydrolysis of Corn Stover by an Integrated Wet-milling and Alkali Pretreatment 总被引:1,自引:0,他引:1
Xun He Yelian Miao Xuejian Jiang Zidong Xu Pingkai Ouyang 《Applied biochemistry and biotechnology》2010,160(8):2449-2457
An integrated wet-milling and alkali pretreatment was applied to corn stover prior to enzymatic hydrolysis. The effects of
NaOH concentration in the pretreatment on crystalline structure, chemical composition, and reducing-sugar yield of corn stover
were investigated, and the mechanism of increasing reducing-sugar yield by the pretreatment was discussed. The experimental
results showed that the crystalline structure of corn stover was disrupted, and lignin was removed, while cellulose and hemicellulose
were retained in corn stover by the pretreatment with 1% NaOH in 1 h. The reducing-sugar yield from the pretreated corn stovers
increased from 20.2% to 46.7% when the NaOH concentration increased from 0% to 1%. The 1% NaOH pretreated corn stover had
a holocellulose conversion of 55.1%. The increase in reducing-sugar yield was related to the crystalline structure disruption
and delignification of corn stover. It was clarified that the pretreatment significantly enhanced the conversion of cellulose
and hemicellulose in the corn stover to sugars. 相似文献
4.
Renata Bura Rodney J. Bothast Shawn D. Mansfield John N. Saddler 《Applied biochemistry and biotechnology》2003,106(1-3):319-335
A batch reactor was employed to steam explode corn fiber at various degrees of severity to evaluate the potential of using
this feedstock as part of an enzymatically mediated cellulose-to-ethanol process. Severity was controlled by altering temperature
(150–230°C), residence time (1–9 min), and SO2 concentration (0–6% [w/w] dry matter). The effects of varying the different parameters were assessed by response surface
modeling. The results indicated that maximum sugar yields (hemicellulose-derived water soluble, and cellulose-derived following
enzymatic hydrolysis) were recovered from corn fiber pretreated at 190°C for 5 minutes after exposure to 3% SO2. Sequential SO2-catalyzed steam explosion and enzymatic hydrolysis resulted in a conversion efficiency of 81% of the combined original hemicellulose
and cellulose in the corn fiber to monomeric sugars. An additional posthydrolysis step performed on water soluble hemicellulose
stream increased the concentration of sugars available for fermentation by 10%, resulting in the high conversion efficiency
of 91%. Saccharomyces cerevisiae was able to ferment the resultant corn fiber hydrolysates, perhydrolysate, and liquid fraction from the posthydrolysis steps
to 89, 94, and 85% of theoretical ethanol conversion, respectively. It was apparent that all of the parameters investigated
during the steam explosion pretreatment had a significant effect on sugar recovery, inhibitory formation, enzymatic conversion
efficiency, and fermentation capacity of the yeast. 相似文献
5.
Pretreatment and enzymatic saccharification of corn fiber 总被引:14,自引:0,他引:14
Corn fiber consists of about 20% starch, 14% cellulose, and 35% hemicellulose, and has the potential to serve as a low-cost
feedstock for production of fuel ethanol. Several pretreatments (hot water, alkali, and dilute, acid) and enzymatic saccharification
procedures were evaluated for the conversion of corn fiber starch, cellulose, and hemicellulose to monomeric sugars. Hot water
pretreatment (121°C, 1 h) facilitated the enzymatic sacch arification of starch and cellulose but not hemicellulose. Hydrolysis
of corn fiber pretreated with alkali un dersimilar conditions by enzymatic means gave similar results. Hemicellulose and starch
components were converted to monomeric sugars by dilute H2SO4 pretreatment (0.5–1.0%, v/v) at 121°C. Based on these findings, a method for pretreatment and enzymatic saccharification
of corn fiber is presented. It in volves the pretreatment of corn fiber (15% solid, w/v) with dilute acid (0.5% H2SO4, v/v) at 121°C for 1 h, neutralization to pH 5.0, then saccharification of the pretreated corn fiber material with commercial
cellulase and β-glucosidase preparations The yield of monomeric sugars from corn fiber was typically 85–100% of the theoretical
yield.
Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard
of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also
be suitable. 相似文献
6.
Söderström Johanna Pilcher Linda Galbe Mats Zacchi Guido 《Applied biochemistry and biotechnology》2002,98(1-9):5-21
Two-step steam pretreatment of softwood was investigated with the aim of improving the enzymatic digestibility for ethanol
production. In the first step, softwood was impregnated with SO2 and steam pretreated at different severities. The first step was performed at low severity to hydrolyze the hemicellulose
and release the sugars into the solution. The combination of time and temperature that yielded the highest amount of hemicellulosic
sugars in the solution was determined. In the second step, the washed solid material from the optimized first step was impregnated
once more with SO2 and steam pretreated under more severe conditions to enhance the enzymatic digestibility. The investigated temperature range
was between 180 and 220°C, and the residence times were 2, 5 and 10 min. The effectiveness of pretreatment was assessed by
both enzymatic hydrolysis of the solids and simultaneous saccharification and fermentation (SSF) of the whole slurry after
the second pretreatment step, in the presence of antibiotics. For each pretreatment combination, the liquid fraction was fermented
to determine any inhibiting effects. At low severity in the second pretreatment step, a high conversion of cellulose was obtained
in the enzymatic hydrolysis step, and at a high severity a high conversion of cellulose was obtained in the second pretreatment
step. This resulted in an overall yield of sugars that was nearly constant over a wide range of severity. Compared with the
one-step steam pretreatment, the two-step steam pretreatment resulted in a higher yield of sugar and in a slightly higher
yield of ethanol. The overall sugar yield, when assessed by enzymatic hydrolysis, reached 80%. In the SSF configuration, an
overall ethanol yield of 69% was attained. 相似文献
7.
Shan Liu Shubiao Wu Changle Pang Wei Li Renjie Dong 《Applied biochemistry and biotechnology》2014,172(3):1365-1376
The microbial pretreatment of corn stover and corn stover silage was achieved via the solid-state cultivation of Phanerochaete chrysosporium; pretreatment effects on the biodegradability and subsequent anaerobic production of biogas were investigated. The peak levels of daily biogas production and CH4 yield from corn stover silage were approximately twice that of corn stover. Results suggested that ensiling was a potential pretreatment method to stimulate biogas production from corn stover. Surface morphology and Fourier-transform infrared spectroscopy analyses demonstrated that the microbial pretreatment of corn stover silage improved biogas production by 10.5 to 19.7 % and CH4 yield by 11.7 to 21.2 % because pretreatment could decrease dry mass loss (14.2 %) and increase substrate biodegradability (19.9 % cellulose, 32.4 % hemicellulose, and 22.6 % lignin). By contrast, the higher dry mass loss in corn stover (55.3 %) after microbial pretreatment was accompanied by 54.7 % cellulose, 64.0 % hemicellulose, and 61.1 % lignin degradation but did not significantly influence biogas production. 相似文献
8.
Wheat straw was pretreated by wet explosion using three different oxidizing agents (H2O2, O2, and air). The effect of the pretreatment was evaluated based on glucose and xylose liberated during enzymatic hydrolysis.
The results showed that pretreatment with the use of O2 as oxidizing agent was the most efficient in enhancing overall convertibility of the raw material to sugars and minimizing
generation of furfural as a by-product. For scale-up of the process, high dry matter (DM) concentrations of 15–20% will be
necessary. However, high DM hydrolysis and fermentation are limited by high viscosity of the material, higher inhibition of
the enzymes, and fermenting microorganism. The wet-explosion pretreatment method enabled relatively high yields from both
enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) to be obtained when performed on unwashed slurry
with 14% DM and a low enzyme loading of 10 FPU/g cellulose in an industrial acceptable time frame of 96 h. Cellulose and hemicellulose
conversion from enzymatic hydrolysis were 70 and 68%, respectively, and an overall ethanol yield from SSF was 68%. 相似文献
9.
Saha Badal C. Dien Bruce S. Bothast Rodney J. 《Applied biochemistry and biotechnology》1998,(1):115-125
Corn fiber, which consists of about 20% starch, 14% cellulose, and 35% hemicellulose, has the potential to serve as a low
cost feedstock for production of fuel ethanol. Currently, the use of corn fiber to produce fuel ethanol faces significant
technical and economic challenges. Its success depends largely on the development of environmentally friendly pretreatment
procedures, highly effective enzyme systems for conversion of pretreated corn fiber to fermentable sugars, and efficient microorganisms
to convert multiple sugars to ethanol. Several promising pretreatment and enzymatic processes for conversion of corn fiber
cellulose, hemicellulose, and remaining starch to fermentable sugars were evaluated. These hydrolyzates were then examined
for ethanol production in bioreactors, using genetically modified bacteria and yeast. Several novel enzymes were also developed
for use in pretreated corn fiber saccharification.
Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard
of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also
be suitable. 相似文献
10.
Zhaobing Shen Chaonan Jin Haisheng Pei Jiping Shi Li Liu Junshe Sun 《Cellulose (London, England)》2014,21(5):3383-3394
Pretreatment has been viewed as the most efficient strategy for lignocellulosic biomass-to-fermentable sugars conversion. In this study a novel pretreatment with acidic electrolyzed water (AEW) and FeCl3 was proposed and tested to deconstruct the recalcitrance of corn stover and enhance its subsequent cellulose-to-sugar conversion. The effects of AEW pH and FeCl3 concentration on hemicellulose degradation were investigated, and the results showed the highest hemicellulose removal (93.40 %) and recovery (93.04 %) were achieved at AEW pH 2.30 and FeCl3 concentration 0.05 mol/L. Further research on the properties of AEW solutions with FeCl3, including their pH, ORP, and DO revealed the synergistic effects of strong acidity and high oxidizing capacity of the solution could boost hemicellulose breakup and enhance the enzymatic hydrolysis of cellulose (92.00 %) by removing most of hemicellulose and increasing the accessibility and digestibility of cellulose. Therefore, these studies prove AEW coupled with FeCl3 pretreatment is an effective and promising approach in biomass-to-biofuel process. 相似文献
11.
Karin Öhgren Mats Galbe Guido Zacchi 《Applied biochemistry and biotechnology》2005,124(1-3):1055-1067
In this study, corn stover with a dry matter content of 20% was impregnated with SO2 and then steam pretreated for various times at various temperatures. The pretreatment was evaluated by enzymatic hydrolysis
of the solid material and analysis of the sugar content in the liquid. The maximum overall yield of glucose, 89% of the theoretical
based on the glucan in the raw material, was achieved when the corn stover was pretreated at 200°C for 10 min. The maximum
overall yield of xylose, 78%, was obtained with pretreatment at 190°C for 5 min. 相似文献
12.
Steam-exploded corn stover biomass was used as the substrate for fed-batch separate enzymatic hydrolysis and fermentation
(SHF) to investigate the solid concentration ranging from 10% to 30% (w/w) on the lignocellulose enzymatic hydrolysis and fermentation. The treatment of washing the steam-exploded material was also
evaluated by experiments. The results showed that cellulose conversion changed little with increasing solid concentration,
and fermentation by Saccharomyces cerevisiae revealed a nearly same ethanol yield with the water-washed steam-exploded corn stover. For the washed material at 30% substrate
concentration, i.e., 30% water insoluble solids (WIS), enzymatic hydrolysis yielded 103.3 g/l glucose solution and a cellulose
conversion of 72.5%, thus a high ethanol level up to 49.5 g/l. With the unwashed steam-exploded corn stover, though a cellulose
conversion of 70.9% was obtained in hydrolysis at 30% solid concentration (27.9% WIS), its hydrolysate did not ferment at
all, and the hydrolysate of 20% solid loading containing 3.3 g/l acetic acid and 145 mg/l furfural already exerted a strong
inhibition on the fermentation and ethanol production. 相似文献
13.
Nóra Szijártó Zsófia Kádár Enikő Varga Anne Belinda Thomsen Maria Costa-Ferreira Kati Réczey 《Applied biochemistry and biotechnology》2009,155(1-3):83-93
Common reed (Phragmites australis) is often recognized as a promising source of renewable energy. However, it is among the least characterized crops from the bioethanol perspective. Although one third of reed dry matter is cellulose, without pretreatment, it resists enzymatic hydrolysis like lignocelluloses usually do. In the present study, wet oxidation was investigated as the pretreatment method to enhance the enzymatic digestibility of reed cellulose to soluble sugars and thus improve the convertibility of reed to ethanol. The most effective treatment increased the digestibility of reed cellulose by cellulases more than three times compared to the untreated control. During this wet oxidation, 51.7% of the hemicellulose and 58.3% of the lignin were solubilized, whereas 87.1% of the cellulose remained in the solids. After enzymatic hydrolysis of pretreated fibers from the same treatment, the conversion of cellulose to glucose was 82.4%. Simultaneous saccharification and fermentation of pretreated solids resulted in a final ethanol concentration as high as 8.7 g/L, yielding 73% of the theoretical. 相似文献
14.
Effects of temperature and moisture on dilute-acid steam explosion pretreatment of corn stover and cellulase enzyme digestibility 总被引:3,自引:0,他引:3
Melvin P. Tucker Kyoung H. Kim Mildred M. Newman Quang A. Nguyen 《Applied biochemistry and biotechnology》2003,105(1-3):165-177
Corn stover is emerging as a viable feedstock for producing bioethanol from renewable resources. Dilute-acid pretreatment
of corn stover can solubilize a significant portion of the hemicellulosic component and enhance the enzymatic digestibility
of the remaining cellulose for fermentation into ethanol. In this study, dilute H2SO4 pretreatment of corn stover was performed in a steam explosion reactor at 160°C, 180°C, and 190°C, approx 1 wt% H2SO4, and 70-s to 840-s residence times. The combined severity (Log10 [R
o
] - pH), an expression relating pH, temperature, and residence time of pretreatment, ranged from 1.8 to 2.4. Soluble xylose
yields varied from 63 to 77% of theoretical from pretreatments of corn stover at 160 and 180°C. However, yields >90% of theoretical
were found with dilute-acid pretreatments at 190°C. A narrower range of higher combined severities was required for pretreatment
to obtain high soluble xylose yields when the moisture content of the acid-impregnated feedstock was increased from 55 to
63 wt%. Simultaneous saccharification and fermentation (SSF) of washed solids from corn stover pretreated at 190°C, using
an enzyme loading of 15 filter paper units (FPU)/g of cellulose, gave ethanol yields in excess of 85%. Similar SSF ethanol
yields were found using washed solid residues from 160 and 180°C pretreatments at similar combined severities but required
a higher enzyme loading of approx 25 FPU/g of cellulose. 相似文献
15.
Daniel J. Schell Jody Farmer Millie Newman James D. McMillan 《Applied biochemistry and biotechnology》2003,105(1-3):69-85
Corn stover is a domestic feedstock that has potential to produce significant quantities of fuel ethanol and other bioenergy
and biobased products. However, comprehensive yield and carbon mass balance information and validated kinetic models for dilute-sulfuric
acid (H2SO4) pretreatment of corn stover have not been available. This has hindered the estimation of process economics and also limited
the ability to perform technoeconomic modeling to guide research. To better characterize pretreatment and assess its kinetics,
we pretreated corn stover in a continuous 1 t/d reactor. Corn stover was pretreated at 20% (w/w) solids concentration over
a range of conditions encompassing residence times of 3–12 min, temperatures of 165–195°C, and H2SO4 concentrations of 0.5–1.4% (w/w). Xylan conversion yield and carbon mass balance data were collected at each run condition.
Performance results were used to estimate kinetic model parameters assuming biphasic hemicellulose hydrolysis and a hydrolysis
mechanism incorporating formation of intermediate xylo-oligomers. In addition, some of the pretreated solids were tested in
a simultaneous saccharification and fermentation (SSF) process to measure the reactivity of their cellulose component to enzymatic
digestion by cellulase enzymes. Monomeric xylose yields of 69–71% and total xylose yields (monomers and oligomers) of 70–77%
were achieved with performance level depending on pretreatment severity. Cellulose conversion yields in SSF of 80–87% were
obtained for some of the most digestible pretreated solids. 相似文献
16.
Nghiem NP Montanti J Johnston DB Drapcho C 《Applied biochemistry and biotechnology》2011,164(8):1390-1404
A process was developed to fractionate and isolate the hemicellulose B component of corn fiber generated by corn wet milling.
The process consisted of pretreatment by soaking in aqueous ammonia followed by enzymatic cellulose hydrolysis, during which
the hemicellulose B was solubilized by cleavage into xylo-oligosaccharides and subsequently recovered by precipitation with
ethanol. The pretreatment step resulted in high retention of major sugars and improvement of subsequent enzymatic hydrolysis.
The recovered hemicellulose B was hydrolyzed by a cocktail of enzymes that consisted of β-glucosidase, pectinase, xylanase,
and ferulic acid esterase (FAE). Xylanase alone was ineffective, demonstrating yields of less than 2% of xylose and arabinose.
The greatest xylose and arabinose yields, 44% and 53%, respectively, were obtained by the combination of pectinase and FAE.
A mass balance accounted for 87% of the initially present glucan, 91% of the xylan, and 90% of the arabinan. The developed
process offered a means for production of corn fiber gum as a value-added co-product and C5 sugars, which could be converted
to other valuable co-products through fermentation in a corn wet-milling biorefinery. 相似文献
17.
Byung-Hwan Um M. Nazmul Karim Linda L. Henk 《Applied biochemistry and biotechnology》2003,105(1-3):115-125
The pretreatment of corn stover with H2SO4 and H3PO4 was investigated. Pretreatments were carried out from 30 to 120 min in a batch reactor at 121°C, with acid concentrations
ranging from 0 to 2% (w/v) at a solid concentration of 5% (w/v). Pretreated corn stover was washed with distilled water until
the filtrate was adjusted to pH 7.0, followed by surfactant swelling of the cellulosic fraction in a 0–10% (w/v) solution
of Tween-80 at room temperature for 12 h. The dilute acid treatment proved to be a very effective method in terms of hemicellulose
recovery and cellulose digetibility. Hemicellulose recovery was 62–90%, and enzymatic digestibility of the cellulose that
remained in the solid was >80% with 2% (w/v) acid. In all cases studied, the performance of H2SO4 pretreatment (hemicellulose recovery and cellulose digestibility) was significantly better than obtained with H3PO4. Enzymatic hydrolysis was more effective using surfactant than without it, producing 10–20% more sugar. Furthermore, digestibility
was investigated as a function of hemicellulose removal. It was found that digestibility was more directly related to hemicellulose
removal than to delignification. 相似文献
18.
Ammonia fiber explosion treatment of corn stover 总被引:1,自引:0,他引:1
Farzaneh Teymouri Lizbeth Laureano-Pérez Hasan Alizadeh Bruce E. Dale 《Applied biochemistry and biotechnology》2004,115(1-3):951-963
Optimizing process conditions and parameters such as ammonia loading, moisture content of biomass, temperature, and residence
time is necessary for maximum effectiveness of the ammonia fiber explosion process. Approximate optimal pretreatment conditions
for corn stover were found to be temperature of 90°C, ammonia: dry corn stover mass ratio of 1∶1, moisture content of corn
stover of 60% (dry weight basis), and residence time (holding at target temperature), of 5 min. Approximately 98% of the theoretical
glucose yield was obtained during enzymatic hydrolysis of the optimal treated corn stover using 60 filter paper units (FPU)
of cellulase enzyme/g of glucan (equal to 22 FPU/g of dry corn stover). The ethanol yield from this sample was increased up
to 2.2 times over that of untreated sample. Lowering enzyme loading to 15 and 7.5 FPU/g of glucan did not significantly affect
the glucose yield compared with 60 FPU, and any differences between effects at different enzyme levels decreased as the treatment
temperature increased. 相似文献
19.
Evaluation and Characterization of Forage Sorghum as Feedstock for Fermentable Sugar Production 总被引:2,自引:0,他引:2
Corredor DY Salazar JM Hohn KL Bean S Bean B Wang D 《Applied biochemistry and biotechnology》2009,158(1):164-179
Sorghum is a tropical grass grown primarily in semiarid and drier parts of the world, especially areas too dry for corn. Sorghum
production also leaves about 58 million tons of by-products composed mainly of cellulose, hemicellulose, and lignin. The low
lignin content of some forage sorghums such as brown midrib makes them more digestible for ethanol production. Successful
use of biomass for biofuel production depends on not only pretreatment methods and efficient processing conditions but also
physical and chemical properties of the biomass. In this study, four varieties of forage sorghum (stems and leaves) were characterized
and evaluated as feedstock for fermentable sugar production. Fourier transform infrared spectroscopy and X-ray diffraction
were used to determine changes in structure and chemical composition of forage sorghum before and after pretreatment and the
enzymatic hydrolysis process. Forage sorghums with a low syringyl/guaiacyl ratio in their lignin structure were easy to hydrolyze
after pretreatment despite the initial lignin content. Enzymatic hydrolysis was also more effective for forage sorghums with
a low crystallinity index and easily transformed crystalline cellulose to amorphous cellulose, despite initial cellulose content.
Up to 72% hexose yield and 94% pentose yield were obtained using modified steam explosion with 2% sulfuric acid at 140 °C
for 30 min and enzymatic hydrolysis with cellulase (15 filter per unit (FPU)/g cellulose) and β-glucosidase (50 cellobiose
units (CBU)/g cellulose). 相似文献
20.
Pretreatment and Fractionation of Corn Stover by Soaking In Ethanol and Aqueous Ammonia 总被引:1,自引:0,他引:1
Tae Hyun Kim Nhuan P. Nghiem Kevin B. Hicks 《Applied biochemistry and biotechnology》2009,153(1-3):171-179
A new process for pretreatment of lignocellulosic biomass, designated the soaking in ethanol and aqueous ammonia (SEAA) process, was developed to improve hemicellulose preservation in solid form. In the SEAA process, an aqueous ammonia solution containing ethanol is used. Corn stover was treated with 15 wt.% ammonia at 1:9 solid–liquid ratio (by weight) at 60 °C for 24 h with ethanol added at 1, 5, 20, and 49 wt.% (balance was water). The extents by which xylan was solubilized with no ethanol and with ethanol added at 1, 5, 20, and 49 wt.% of the total liquid were 17.2%, 16.7%, 14.5%, 10.4%, and 6.3% of the original xylan, respectively. Thus, at the highest ethanol concentration used the loss of hemicellulose to the liquid phase was reduced by 63%. The digestibility of glucan and xylan in the pretreated corn stover samples by cellulase was not affected by ethanol addition of up to 20 wt.%. The enzymatic digestibility of the corn stover treated with 49 wt.% ethanol added was lower than the digestibility of the sample treated with no ethanol addition. Thus, based on these results, 20 wt.% was found to be the optimum ethanol concentration for use in the SEAA process for pretreatment of corn stover. 相似文献