Production Of Fermentable Sugars Research Articles

Improvement of fermentable sugar extraction from hazelnut shells through microwave assisted dilute acid pretreatment

The most effective method for producing fermentable sugars (FSs) from biomass is thermochemical pretreatment assisted by enzymatic hydrolysis. However, the enzymatic hydrolysis-assisted thermochemical pretreatment method is limited by the formation of fermentation inhibitors, and it is time-consuming. There is growing interest in using a microwave (MW) pretreatment due to its uniform and rapid heating. This study aimed to determine, perform data-driven modeling, and optimize the effect of MW combined with dilute acid pretreatment (MW-DA) on the production of FSs from hazelnut shells. An artificial neural networks (ANNs) model based on Box-Behnken Design (BBD) was the best model described for fermentable sugar extraction (FSE). Optimization via BBD-based ANNs model was carried out for an acid concentration of 0.5 to 2% (w/w), a pretreatment time of 5 to 25 min, a pressure of 5 to 15 bar, and a temperature of 120 to 160 °C. The optimized FSE was estimated at 374 mg/g (81.4% conversion efficiency), with a severity factor of 3.61 under 1.58% H2SO4 for 13 min at 160 °C and 8.5 bar. Using the MW-DA pretreatment process lowered the costs significantly due to the decreases in acid concentration and pretreatment time.

Additives Enhancing Enzymatic Hydrolysis of Wheat Straw to Obtain Fermentable Sugar.

In order to explore the effect of additives on enzymatic hydrolysis of lignocellulose biomass, the effect of two different additives, Triton X-100 (TX-100) and Bovine serum albumin (BSA), enzyme dosages, and additive concentrations on enzymatic hydrolysis to obtain fermentable sugar using cellulose extracted from wheat straw (WS) as the substrate was investigated in this study. An enzymatic hydrolysis kinetic model was used to successfully describe the enzymatic hydrolysis in a heterogeneous system. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were used to determine the effect of extraction and enzymatic hydrolysis on the composition and structure of the samples. The results showed that the total reducing sugar concentration of the raw was 1.535g/L at 120h, but that of the extracted cellulose (EC) increased to 5.087g/L at 120h, indicating that EC from WS is more conducive to enzymatic hydrolysis compared with the raw. The total reducing sugar concentration with the addition of the TX-100 was 6.737g/L at 120h, which was greater than that with the addition of the BSA (5.728g/L at 120h), indicating that the addition of two additives improved the enzymatic hydrolysis efficiency, especially TX-100. The kinetic studies showed that the initial enzymatic hydrolysis reaction rate (Km) of the EC was more than four times greater than that of the raw. The Km of the EC added with TX-100 and BSA were increased by 29.50% and 22.89% compared with that of the EC without the addition of additive. The addition of additives is an effective method for enhancing enzymatic hydrolysis efficiency and fermentable sugar production from lignocellulosic biomass.

Impact of mashing protocol on the formation of fermentable sugars from millet in gluten-free brewing

The production of fermentable sugars (FS) in gluten-free (GF) brewing is hindered by the high starch gelatinization temperatures of GF malts and lower diastatic power compared to barley malt. Our previous work has demonstrated that starch gelatinization was the primary hurdle, and when decoupled from a single mash phase, high concentrations of FS could be produced. However, more research was required to improve the applicability of GF brewing. In this study, millet was used as a model GF malt demonstrating that despite the low α-amylase and β-amylase activities compared to barley malt ∼ 90 % of the FS (∼110 g/L) could be produced within 40 min. Limitations to enzyme extraction and separation due to coarse milling and lautering initially limited FS by ∼ 30 g/L, requiring additional processing or exogenous enzyme supplements that improved fermentable sugar generation by ∼ 20 g/L. Overall, millet is a promising brewing ingredient, provided appropriate mashing procedures are implemented.

Optimization of Concentrated Sulphuric Acid Hydrolysis of Gadam Sorghum Stalks Found in Kenya for Fermentable Sugar Production

Gadam sorghum stalks are agricultural residues which can be hydrolyzed into fermentable sugars that can be used to produce bioethanol which is a renewable source of energy. In order to produce bioethanol from lignocellulosic biomass such as Gadam sorghum stalks, several processes including hydrolysis are involved. However, the use of lignocellulosic biomass for bioethanol production is hindered by the low yield of fermentable sugars obtained during hydrolysis. The lack of sufficient information on optimal conditions governing hydrolysis of lignocellulosic biomass leads to inefficient process which hinders the economic viability of large-scale bioethanol production. The objective of this study was to optimize reaction conditions involved in concentrated sulphuric acid hydrolysis of Gadam sorghum stalks. During hydrolysis, the conditions that were varied included temperature (40°C–80°C), time (30-90 minutes), and concentration of acid (30%-70%,w/w). Central composite rotatable design was used to optimize and establish optimum level of hydrolysis conditions. Response surface methodology and analysis of variance were used to interprete the results. The results of hydrolysis revealed that the highest yield of glucose was 87.54% (w/w) which was realized at 60°C hydrolysis temperature, 60 minutes hydrolysis period, and 50% (w/w) concentration of sulphuric acid. In addition, the lowest glucose yield was 45.59% (w/w) which was realized at 60°C hydrolysis temperature, 60 minutes hydrolysis period, and 16.36% (w/w) sulphuric acid concentration. Concentrated sulphuric acid hydrolysis of Gadam sorghum stalks results in high yield of fermentable sugars. These results reveal that Gadam sorghum stalks are viable substrates for the production of fermentable sugars.

Proposal for the conversion of Eucalyptus urograndis into bioethanol via acid hydrolysis, using the concepts of biorefineries

Abstract The production of bioethanol from materials of renewable origin is an important matter for a more sustainable economic development, and at the same time it challenges researchers to seek more efficient technologies that can make it viable. Wood is a profitable and advantageous option, with special emphasis on eucalyptus, whose cultivation has high turnover in Brazil, where land is available for this purpose. Therefore, the goal of this research was to optimize the hydrolysis stage using acid instead of enzymes for the conversion of chips of Eucalyptus urograndis into bioethanol, with additional co-production of furfural and commercial lignin, in order to make the process more advantageous. To obtain bioethanol, a pre-treatment adapted from autohydrolysis was performed to remove the hemicelluloses, followed by soda pulping to remove the lignin and, finally, the acid hydrolysis of the β-(1→4) glycosidic bonds between the C1–C4 cellulose carbons releasing β-D-glucose monomers to be fermented into bioethanol. In the acid hydrolysis step, sulfuric acid of concentration 1127 gL−1 was used. After the experimental analyses performed, it could be observed that in acid hydrolysis, treatments using 70 mL and 80 mL of sulfuric acid did not differ statistically in relation to glucose production. However, by increasing the volume of acid to 90 mL, there was an increase in the production of fermentable sugars into bioethanol, 63.7 %, which began decreasing when adding acid above 93 mL, because the excess of acid also caused the degradation of sugars into 5-hydroxymethylfurfural (HMF); and in the treatment of 100 mL there was a higher production of HMF. The production of bioethanol proved to be competitive after the fermentation of the sample from the 90 mL treatment with a production of 103.7 L of bioethanol/ton of wood, in addition to being beneficial to the process as a whole with the co-production of furfural, 28.8 kg of furfural ton−1 of wood, and commercial lignin, 428.3 kg of lignin per ton of wood, precursors to various chemicals such as resins, coatings and inks.

A new l-cysteine-assisted glycerol organosolv pretreatment for improved enzymatic hydrolysis of corn stover

Deconstruction of lignocellulose via efficient pretreatment is crucial for producing fermentable sugars. In this study, effects of glycerol organosolv pretreatment (GOP) on main chemical composition of corn stover were investigated. Results indicate that the residual corn stover after 80 wt% glycerol pretreatment (at 220 °C for 0.5 h) yielded 75.97 % glucose and 78.21 % xylose after enzymatic hydrolysis, which were enhanced by 3.39- and 6.08-fold compared to the untreated corn stover. Subsequently, an l-cysteine-assisted GOP was proposed with higher yields of glucose (86.20 %) and xylose (91.13 %). When pretreating corn stover with 80 wt% glycerol containing 0.07 wt% l-cysteine at 220 °C for 0.5 h, higher fermentable sugars of 26.08 g were produced from 100 g feedstock after enzymolysis. Intrinsic mechanisms of the proposed pretreatment for enhancing enzymatic digestibility were elucidated by physiochemical characterization technologies and techno-economic analysis was also studied. This study provides guidance for fermentable sugars production from renewable lignocellulose.

Combinatorial pretreatments of reed straw using liquid hot water and lactic acid for fermentable sugar production

A green combinatorial pretreatment using liquid hot water (LHW) and lactic acid (LA) was used to treat reed straw for effective lignocellulose digestibility and xylose recovery. The reeds were first treated with LHW at 180 °C for 60 min, followed by LA treatment at 170 °C for 45 min. Using 37.5 g/L lactic acid, the lignocellulose digestibility was 80.6 % and glucose yield was 56.0 %, which was much higher than that for one-step LHW pretreatment (the lignocellulose digestibility was 27.3 % and the glucose yield was 26.3 %). These data demonstrated that LHW-LA pretreatment increased lignocellulose digestibility and glucose yield by 1.95-fold and 1.13-fold, respectively. The highest total sugar yielded 39.2 g/100 g-substrate. The results revealed that LHW-LA pretreatment removed most hemicellulose and partial lignin from the reed straw and prompted cellulase binding to reed cellulose, which enhanced lignocellulose enzymatic saccharification. The high fermentable glucose yielded from the combinatorial pretreatment as presented in this study highlighted the great potential of our pretreatment technology to be applied in the biorefinery, which could lay down the cost and sustainability of current biorefinery industry.

Positive role of non-catalytic proteins on mitigating inhibitory effects of lignin and enhancing cellulase activity in enzymatic hydrolysis: Application, mechanism, and prospective

Fermentable sugar production from lignocellulosic biomass has received considerable attention and has been dramatic progress recently. However, due to low enzymatic hydrolysis (EH) yields and rates, a high dosage of the costly enzyme is required, which is a bottleneck for commercial applications. Over the last decades, various strategies have been developed to reduce cellulase enzyme costs. The progress of the non-catalytic additive proteins in mitigating inhibition in EH is discussed in detail in this review. The low efficiency of EH is mostly due to soluble lignin compounds, insoluble lignin, and harsh thermal and mechanical conditions of the EH process. Adding non-catalytic proteins into the EH is considered a simple and efficient approach to boost hydrolysis yield. This review discussed the multiple mechanical steps involved in the EH process. The effect of physicochemical properties of modified lignin on EH and its interaction with cellulase and cellulose are identified and discussed, which include hydrogen bonding, hydrophobic, electrostatic, and cation-π interactions, as well as physical barriers. Moreover, the effects of different conditions of EH that lead to cellulase deactivation by thermal and mechanical mechanisms are also explained. Finally, recent advances in the development, potential mechanisms, and economic feasibility of non-catalytic proteins on EH are evaluated and perspectives are presented.

Using organosolv pretreatment with acid wastewater for enhanced fermentable sugar and ethanol production from rubberwood waste

The intensive utilization of water in the pretreatment of substrates for lignocellulosic ethanol production negatively impacts its economic feasibility. This study aimed to develop a method of pretreatment using acid wastewater to enhance the conversion of rubberwood waste into fermentable sugar and ethanol. The water was replaced with acid wastewater in hydrothermal pretreatments with and without alkaline post-treatment, and organosolv pretreatment (wastewater:ethanol 50:50). The organosolv pretreatment at 190 °C maximized the fermentable sugar concentration (43.60 g/L) and yield (301.0 ± 13.3 kg/ton rubberwood waste) because of partial delignification and physical redistribution of the rubberwood waste matrix. It also demonstrated markedly better reduction of water utilization, wastewater generation, and energy consumption than other pretreatments. In addition, the hydrolysate derived from the organosolv pretreatment was chosen for ethanol production. Saccharomyces cerevisiae showed better ethanol conversion rate than Kluyveromyces marxianus when the hydrolysate predominantly contained glucose, resulting in an ethanol production of 0.14 g/g rubberwood waste. The pretreatment and fermentation were effective and exhibited the potential to guide lignocellulosic ethanol production in collaboration with latex factories (acid wastewater sources) in future practical applications.

Pretreatment of barley straw with acid and alkaline solutions to boost the efficiency of fermentable yield enzymatic degradation in the separated fermentation technique for ethanol production

Barley straw is a lignocellulose agricultural waste material that can be utilized as a raw material for ethanol production since it is easy to find, cheap, and has the potential to produce ethanol yield. This research aims to select the optimum pretreatment conditions to increase fermentable sugar production during enzymatic hydrolysis for bioethanol production. Initially, sulfuric acid at a concentration of 0.5, 1.0, 1.5, and 2.0% (v/v) pre-treated barley straw biomass was applied by autoclaving at 121℃ for 15 lb/in2 pressure for 15 min. Furthermore, acid-treated barley straw under the alkaline condition with calcium hydroxide concentrations of 1, 2, 3, and 4% (w/v) was autoclaved at 121℃ for 15 lb/in2 pressure for 15 min. Subsequently, the pretreatment of barley straw in the acetic and alkaline processes was compared. It was found that calcium hydroxide at a concentration of 2% (w/v) gave more sugar concentrations. Finally, combined acid and alkaline pretreatment with 2% of cellulase enzymatic hydrolysis had the highest total sugar concentration of 205.43 g/L and reducing sugar of 134.42 g/L, producing the highest ethanol yield (16.17 g/L) by 24 hours of fermentation.

Statistical optimization of pretreatment of municipal solid waste by response surface methodology for fermentable sugar production

AbstractThis research aims to use low‐cost and easily available chemicals for chemical pretreatment to achieve a high yield of fermentable sugars using biodegradable municipal solid waste as a substrate. Biodegradable municipal solid waste was pretreated with locally available toilet cleaner (acidic in nature) and washing detergent (basic in nature) and to achieve maximum yield of reducing sugars, two variables; chemical concentration and time were selected for optimization using a central composite design. In Central composite design 13 runs for toilet cleaner (acidic in nature) and washing detergent (basic in nature) pretreatment models were created while ranges for two variables were selected as 1, 2, 3 days for time and 1%, 3%, 5% for chemical concentration. In the toilet cleaner (acidic in nature) pretreatment, optimum conditions were 5% (vol/vol) of toilet cleaner (acidic in nature) for 3 days. At optimal conditions, the model for toilet cleaner (acidic in nature) pretreatment released 167.755 g/L of reducing sugars and 2.684 MJ/L energy while the model for washing detergent (basic in nature) pretreatment released 159.141 g/L of reducing sugars and 2.546 MJ/L energy. An enzyme cocktail hydrolyzed the toilet cleaner (acidic in nature) pretreated sample, and the highest value of fermentable sugar was achieved at 36 h of 237.83 ± 11.028 g/L. Thus, the chemical pretreatment using toilet cleaner and washing detergent has a great potential for fermentable sugar production and effectively be used in industrial and household digesters for the conversion of waste into useful products.

Evaluation of acid-thermal pretreatments and enzymatic saccharification to obtain fermentable sugars from the juice and bagasse of Agave salmiana leaves

This study presents the results of acid-thermal pretreatments and enzymatic saccharification for the production of fermentable sugars from the juice and bagasse of Agave salmiana leaves. In the acid-thermal pretreatment, H2SO4 was used while in the enzymatic saccharification the commercial enzyme Cellic Ctec2 (Novozyme) was used. In the results it was found that the best conditions of the acid thermal pretreatment (H2SO4 % (v/v) at 100 ° C for 30 min) for the juice generated a concentration of 43.65 ± 1.36 g/L of reducing sugars. In bagasse, the best conditions (H2SO4 % (p/v) at 120 ° C for 60 min) produced a concentration of 37.35 ± 1.65 g/L of reducing sugars in the hydrolysates. In the enzymatic saccharification at 15 FPU/g substrate and solids load of 10 % (p/v), a concentration of 87.37 ± 1.27 g/L of reducing sugars was obtained after 72 h. The results obtained demonstrate the potential of the integral use of bagasse and juices from the leaves of Agave salmiana as raw material to produce fermentable sugars.

Evaluation of RSM and ANFIS modeling performance in fermentable sugar production from Enzymatic Hydrolysis Of Colocynthis vulgaris shrad seeds shell

This study is on the modeling of fermentable sugar production process; obtained by enzymatic hydrolysis of Colocynthis vulgaris Shrad seeds shell (CVSSS) using the response surface methodology (RSM) and adaptive neuro-fuzzy inference system (ANFIS). The sugar was hydrolysed from the CVSSS using Aspergillus Niger isolated from soil. The RSM and ANFIS models were evaluated by considering the hydrolysing temperature, time and pH as input variables, whereas the percentage yield of sugar was the response factor or the output factor. Four statistical error tasks were additionally, applied to relate the adequacy of the two models. The result showed that, fermentable sugar can be obtained from the CVSSS with A. niger as a biocatalyst. The ANFIS and RSM tools presented a nigh perfection, in predicting the yield of fermentable sugar from CVSSS with R squared value of 0.9986 and 0.9975, correspondingly. Additional statistical guides gave acceptance to ANFIS as a better predictive tool, in the enzymatic hydrolysis of CVSSS. Optimization result with ANFIS tool, presented an optimum hydrolysis efficiency of 60.65%.

Evaluating the Potentials of Banana and Plantain Peels for Biofuel Production in Nigeria

This study was carried out to assess the potentials of banana and plantain peel as feedstock for biofuel production. The proximate and mineral composition of banana and plantain peel were determined using the AOAC method. Bacteria were isolated from dried banana and plantain peel using the standard microbiological method. The proximate composition of the two biomass showed a high concentration of carbohydrate content at 68.12 and 68.30% for banana and plantain peels. While a high amount of sodium (Na) at 119.17 and 106.67 mg/kg from banana and plantain peels. Three (3) bacterial genera were isolated namely Bacillus circulans, Bacillus brevis and Bacillus pumilu. This study showed the potential of banana and plantain peels biomass for the production of fermentable sugar which can be further fermented to biofuel.

Potential of canola feedstocks for fermentable sugars production by subcritical water hydrolysis

The current study aimed to obtain fermentable sugars from canola waste feedstocks cultivated different harvests by SWH. The processing conditions were temperature of 230 °C, water/solids mass ratios of 4 and 8 g water/g feedstock, and reaction time of 60–1800 s. For H433 silique 2019 and H575 stalk 2020, the highest fermentable sugar yields were obtained, resulting in 10.2 g/100 g silique and 11.5 g/100 g stalk, respectively. For all stalk and silique biomasses, xylose and cellobiose presented a high content. Organic acid yield was higher for DH canola silique (16.22 g/100 g silique). Accordingly, this study pioneered the exploration of the potential of canola lignocellulosic materials to produce fermentable sugars, which can be broadly encouraging when applied in the bioethanol industry.

Fermentation of Trichoderma Reesei PKJ and Aspergillus Niger FNCC 6 to Improve the Production of Fermentable Sugar from Sago Meal

"Lignocellulosic compounds from sago waste are abundant, inexpensive, untapped carbon sources, and even tend to pollute the environment. Trichoderma reesei and Aspergillus niger are two fungi that are widely used to degrade lignocellulose compounds into simple sugars. T. reesei plays the first role to degrade cellulose. Then A niger will play a role in continuing the process of changing the product of cellulose degradation into simple sugars. The right combination of time to inoculate A. niger into media after T. reesei growing in could maximize the degradation process of lignocellulose compounds. In this study, T. reesei Pk1J2 inoculation was carried out 48 hours before the A. niger FNCC 6114 inoculation. Fermentation was continued in 48 h (total 96 h). The result is that the production of fermentable sugar increases 3-5 times compared to only using monoculture of T reesei or A.niger. Thus, this combination can be recommended for the preparation of potential carbon sources for fermentation and industrialization."

Optimization of lignin extraction by response surface methodology from sugarcane bagasse using deep eutectic solvents (DES)

Lignin removal in lignocellulosic biomass is an important step to obtain efficient fermentable sugars production during enzymatic hydrolysis. Likewise, interest has emerged in the past few years for the application of eco-friendly technology for biomass delignification. Thus, the use of deep eutectic solvents has been considered as an alternative to treat lignocellulosic biomass. The main objective of this work was to optimize the sugarcane bagasse delignification using deep eutectic solvents (DES): ChCl-Gly and ChCl-Urea. Previously, the effect of temperature (80–120 °C) and reaction time (2–6 h) were evaluated. Then, response surface methodology was used to optimize the conditions of reaction time, liquid-solid ratio (LSR), and temperature. The results found in this investigation showed that the increase of the reaction time and temperature improve the lignin removal. The optimization revealed that under optimal conditions it is possible to remove an 81.1% (13.12 h, LSR 23.4:1 and 160 °C) and 82% (14.04 h, LSR 17:1 y 160 °C) of the lignin in the sugarcane bagasse using ChCl-Gly and ChCl-Urea, respectively. Also, it is possible to convert 50–80% of the cellulose in sugarcane bagasse after the treatment with DES. This demonstrates that the use of DES is efficient and useful to remove the lignin from lignocellulosic biomass.

P-Toluenesulfonic acid combined with hydrogen peroxide-assisted pretreatment improves the production of fermentable sugars from walnut (Juglans regia L.) shells

This study presents p-toluenesulfonic acid (p-TsOH) pretreatment combined with subsequent hydrogen-peroxide pretreatment for the fractionation of all lignocellulosic components from walnut shells (WNS). The main focus of this study is the production of fermentable sugars. During p-TsOH pretreatment (55% p-TsOH, 1:10 solid-to-liquid ratio, 90 °C, 120 min), 50.2% of lignin and 88.3% of xylan were dissolved. Subsequently, the p-TsOH pretreated WNS without washing (to reduce water consumption) was further pretreated with 40% (v/v) H2O2 and 74.6% of lignin was removed at 60 °C for 120 min. Compared with the glucose yield of 10.2% from p-TsOH pretreated WNS, the glucose yield from the p-TsOH/H2O2 pretreated WNS could be significantly improved to 94.4%. Structural characterization analysis showed increases in porosity, biomass disruption, and cellulose crystallinity during p-TsOH/H2O2 pretreatment. Mass balance demonstrated that 1000 g of WNS produced 295.1 g of fermentable sugars (263.6 g glucose and 31.5 g xylose).

Crops with potential for diclosulam remediation and concomitant bioenergy production

The objective of this work was to evaluate crops for their ability to phytoremediate diclosulam residues in the soil and produce lignocellulosic ethanol. Physiological characteristics, biomass production, soil cover rate, fermentable sugar production and lignocellulosic ethanol production potential of the crops were evaluated in soil with diclosulam residues. The experimental design was a randomized block with four replications. The treatments were arranged in a 4 × 2 factorial scheme with the following crops as the first factor: Avena sativa, Canavalia ensiformis, Mucuna aterrima, and Pennisetum glaucum. The second factor was the presence or absence of the herbicide diclosulam in the soil (30 g ha−1). The physiological variables of the plant species were not affected by the presence of diclosulam; the soil cover of P. glaucum was lower in the area with diclosulam, with a value of 26%. The levels of glucose were not affected by the presence of diclosulam in A. sativa, C. ensiformis, and M. aterrima, indicate not change the estimated yield of ethanol for this species. Avena sativa and Pennisetum glaucum have the potential to phytoremediate soils containing diclosulam residues, with concomitant lignocellulosic ethanol production ability.

An Approach to Correlate Chemical Pretreatment to Digestibility Through Biomass Characterization by SEM, FTIR and XRD

A comprehensive study was carried out to assess the efficiency of different chemicals on the pretreatment of plant biomass, corn cobs. The efficiency was assessed based on its effect on subsequent hydrolysis of biomass for the conversion to fermentable sugars. Both alkali- and acid-based pretreatments were carried out under optimized conditions to avoid the formation of inhibitors and also to yield more sugars. Among the different chemicals used, 2% NaOH (w/v) was found to be effective with the delignification efficiency of 84.32%, and furthermore, the biomass saccharification efficiency was found to be 86.28% using 1.20% (v/v) HNO3 at 100°C for 90 min, whereas the pretreatment with other chemicals such as KOH, NaClO2, Na2SO3, and NH3 had significantly (p < 0.05) low delignification, which ultimately reduced the saccharification efficiency. In acid–base-based pretreatment, 1.5% (v/v) HNO3 resulted in 63.42% delignification along with 68% digestion of hemicelluloses. The effect of pretreatment efficiency on digestibility was investigated by biomass characterization using SEM, FTIR, and XRD analyses before and after the treatment process. The imaging studies clearly indicated that 2% NaOH efficiently digested the complex matrix alignment and enhanced the surface area of the carbohydrate polymer which had shown a positive impact on the rate of hydrolysis. The study concludes that alkali-based pretreatment is the efficient and cost-viable technique for the effective valorization of corn cobs for the production of fermentable sugars which can be further converted to various valuable bioproducts.