Performances comparison between three technologies for continuous ethanol production from molasses

Molasses are a potential feedstock for ethanol production. The successful application of anaerobic fermentation for ethanol production from molasses is critically dependent to the development and the use of high rate bioreactors. In this study the fermentation of sugar cane molasses by Saccharomyces cerevisiae for the ethanol production in a continuously stirred tank reactor (CSTR), an immobilised cell reactor (ICR) and a membrane reactor (MBR) was investigated. Ethanol production and reactor productivities were compared under different dilution rates (D). When using the CSTR, a decent ethanol productivity (Qp) of 6.8 g L⁻¹ h⁻¹ was obtained at a dilution rate of 0.5 h⁻¹. The Qp was improved by 48% and the residual sugar concentration was reduced by using the ICR. Intensifying the production of ethanol was investigated in the MBR to achieve a maximum ethanol concentration and a Qp of 46.5 g L⁻¹ and 19.2 g L⁻¹ h⁻¹, respectively. The achieved results in the MBR worked with high substrate concentration are promising for the scale up operation.     

Ethanol production by Mucor indicus and Rhizopus oryzae from rice straw by separate hydrolysis and fermentation

Rice straw was successfully converted to ethanol by separate enzymatic hydrolysis and fermentation by Mucor indicus, Rhizopus oryzae, and Saccharomyces cerevisiae. The hydrolysis temperature and pH of commercial cellulase and β-glucosidase enzymes were first investigated and their best performance obtained at 45 °C and pH 5.0. The pretreatment of the straw with dilute-acid hydrolysis resulted in 0.72 g g^?1 sugar yield during 48 h enzymatic hydrolysis, which was higher than steam-pretreated (0.60 g g^?1) and untreated straw (0.46 g g^?1). Furthermore, increasing the concentration of the dilute-acid pretreated straw from 20 to 50 and 100 g L^?1 resulted in 13% and 16% lower sugar yield, respectively. Anaerobic cultivation of the hydrolyzates with M. indicus resulted in 0.36–0.43 g g^?1 ethanol, 0.11–0.17 g g^?1 biomass, and 0.04–0.06 g g^?1 glycerol, which is comparable with the corresponding yields by S. cerevisiae (0.37–0.45 g g^?1 ethanol, 0.04–0.10 g g^?1 biomass and 0.05–0.07 glycerol). These two fungi produced no other major metabolite from the straw and completed the cultivation in less than 25 h. However, R. oryzae produced lactic acid as the major by-product with yield of 0.05–0.09 g g^?1. This fungus had ethanol, biomass and glycerol yields of 0.33–0.41, 0.06–0.12, and 0.03–0.04 g g^?1, respectively.     

Simultaneous saccharification and fermentation (SSF) of very high gravity (VHG) potato mash for the production of ethanol

Simultaneous saccharification and fermentation (SSF) of very high gravity (VHG) potato mash, containing 304 g L^?1 of dissolved carbohydrates, was carried out for ethanol production. Potato tubers were ground into a mash, which was highly viscous. Mash viscosity was reduced by the pretreatment with mixed enzyme preparations of pectinase, cellulase and hemicellulase. The enzymatic pretreatment established the use of VHG mash with a suitable viscosity. Starch in the pretreated mash was liquefied to maltodextrins by the action of thermo-stable α-amylase at 85 °C. SSF of liquefied mash was performed at 30 °C with the simultaneous addition of glucoamylase, yeast (Saccharomyces cerevisiae) and ammonium sulfate as a nitrogen source for the yeast. The optimal glucoamylase loading, ammonium sulfate concentration and fermentation time were 1.65 AGU g^?1, 30.2 mM and 61.5 h, respectively, obtained using the response surface methodology (RSM). Ammonium sulfate supplementation was necessary to avoid stuck fermentation under VHG condition. Using the optimized condition, ethanol yield of 16.61% (v/v) was achieved, which was equivalent to 89.7% of the theoretical yield.     

Conversion of paper sludge to ethanol by separate hydrolysis and fermentation (SHF) using Saccharomyces cerevisiae

The conversion of ethanol from paper sludge using the separate hydrolysis and fermentation (SHF) process with cellulase and Saccharomyces cerevisiae GIM-2 were investigated in this paper. Optimization strategy based on statistical experimental designs was employed to enhance degree of saccharification by enzymatic hydrolysis of paper sludge. Based on the Plackett-Burman design, hydrolysis time, substrate concentration and cellulase dosage were selected as the most significant variable on the degree of saccharification. Subsequently, the optimum combination of the selected factors was investigated by a Box-Behnken approach. A mathematical model was developed to show the effects of each factor and their combinatorial interactions on the degree of saccharification. The optimal conditions were hydrolysis time 82.7 h, substrate concentration 40.8 g L⁻¹ and cellulase dosage 18.1 FPU g⁻¹ substrate, and a degree of saccharification of 82.1% can be achieved. When hydrolysate was further fermented with S. cerevisiae GIM-2, the conversion rate of sugar to ethanol was 34.2% and the ethanol yield was 190 g kg⁻¹ of dry paper sludge, corresponding to an overall conversion yield of 56.3% of the available carbohydrates on the initial substrate. The results derived from this study indicate that the response surface methodology is a useful tool for optimizing the hydrolysis conditions to converse paper sludge to ethanol.     

Cellulase production using biomass feed stock and its application in lignocellulose saccharification for bio-ethanol production

A major constraint in the enzymatic saccharification of biomass for ethanol production is the cost of cellulase enzymes. Production cost of cellulases may be brought down by multifaceted approaches which include the use of cheap lignocellulosic substrates for fermentation production of the enzyme, and the use of cost efficient fermentation strategies like solid state fermentation (SSF). In the present study, cellulolytic enzymes for biomass hydrolysis were produced using solid state fermentation on wheat bran as substrate. Crude cellulase and a relatively glucose tolerant BGL were produced using fungi Trichoderma reesei RUT C30 and Aspergillus niger MTCC 7956, respectively. Saccharification of three different feed stock, i.e. sugar cane bagasse, rice straw and water hyacinth biomass was studied using the enzymes. Saccharification was performed with 50 FPU of cellulase and 10 U of β-glucosidase per gram of pretreated biomass. Highest yield of reducing sugars (26.3 g/L) was obtained from rice straw followed by sugar cane bagasse (17.79 g/L). The enzymatic hydrolysate of rice straw was used as substrate for ethanol production by Saccharomyces cerevisiae. The yield of ethanol was 0.093 g per gram of pretreated rice straw.     

Aerobic and anaerobic sequential culture fermentation (AASF) to produce bio-hydrogen from steam-exploded cornstalk

A novel aerobic and anaerobic sequential culture fermentation (AASF) method was designed to improve the conversion efficiency of steam-exploded cornstalk during bio-hydrogen production. The enzyme activities of cellulase and β-glucosidase produced by Trichoderma viride ACCC 30169 were 76.79 FPU g⁻¹ dry weight and 45.23 IU g⁻¹ dry weight after 6-days steam-exploded cornstalk fermentation, respectively. The aerobic fermentation residue was used as the substrate for bio-hydrogen production by Clostridium butyricum AS1.209 anaerobic fermentation. The optimum solid-to-liquid ratio of the anaerobic fermentation substrate was 1:5. The maximum bio-hydrogen yield was attained on the medium with addition of 0.1 g g⁻¹ substrate urea after 2 days of aerobic fermentation. Compared with simultaneous saccharification and fermentation (SSF), AASF for bio-hydrogen production could shorten the fermentation period by at least 66% and the hydrogen yield reached 83% of the total volume after 24 h of anaerobic fermentation. AASF from steam-exploded cornstalk was an effective way for bio-hydrogen production without additional commercial cellulase.     

Comparative study on ethanol production from pretreated sugarcane bagasse using immobilized Saccharomyces cerevisiae on various matrices

Microwave alkali pretreated sugarcane bagasse was used as a substrate for production of cellulolytic enzymes, needed for biomass hydrolysis. The pretreated sugarcane bagasse was enzymatic hydrolyzed by crude unprocessed enzymes cellulase (Filter paper activity 9.4 FPU/g), endoglucanase (carboxymethylcellulase, 148 IU/g), β-glucosidase (116 IU/g) and xylanase (201 IU/g) produced by Aspergillus flavus using pretreated sugarcane bagasse as substrate under solid state fermentation. Concentrated enzymatic hydrolyzate was used for ethanol production using Saccharomyces cerevisiae immobilized on various matrices. The yield of ethanol was 0.44 g_p/g_s in case of yeast immobilized sugarcane bagasse, 0.38 g_p/g_s using Ca-alginate and 0.33 g_p/g_s using agar-agar as immobilization matrices. The immobilized yeast studied up to 10 cycles in case of immobilized sugarcane bagasse and up to 4 cycles in case of agar-agar and calcium alginate for ethanol production under repeated batch fermentation study.     

Biohydrogen production from Humulus scandens by dark fermentation: Potential evaluation and process optimization

As a perennial grass, Humulus scandens is rich in cellulose which can be fermented for bioenergy producing. Hence, the hydrogen production potential of the Humulus scandens from dark fermentation by Enterobacter aerogenes was investigated in this paper. Cellulase amount, inoculation amount, and initial pH value were evaluated. The interrelationship between these factors were studied by Response Surface Box-Behnken Experiments. Results showed that there was a significant correlation between the three factors. Through the correction of the regression equation, the optimized technological conditions were obtained. The amount of cellulase was 0.203 g g⁻¹ TS, the inoculation amount was 42.6%, the initial pH value was 6.59, the pre-estimated maximum cumulative value of hydrogen production was 65.12 mL g⁻¹ TS, and it was similar to the test mean value which was 64.08 mL g⁻¹ TS.     

Characterization,pretreatment and saccharification of spent seaweed biomass for bioethanol production using baker's yeast

Seaweeds are marine macroalgae found abundantly and viewed as potential source of phycocolloids to produce biofuel. In this study, seaweed spent biomass obtained from alginate production industry and biomass obtained after pigment extraction were found to contain a considerable amount of phycocolloids. These two spent biomasses were investigated for the production of ethanol. In this study, the red seaweed spent biomass of Gracilaria corticata var corticata showed higher content of polysaccharide (190.71 ± 30.67 mg g⁻¹ dry weight) than brown seaweed spent biomass (industrial) (136.28 ± 30.09 mg g⁻¹ dry weight). Hydrolysis of spent biomasses with different concentrations of sulfuric acid (0.1%, 0.5% and 1%) was also investigated. Brown seaweed spent biomass and red seaweed spent biomass exhibited high amount of sugar in 0.5% and 1% sulfuric acid treatment, respectively. Proximate and ultimate composition of seaweed spent biomasses were analysed for energy value. The FT-Raman spectra exhibited similar stretches for both acid hydrolysed spent biomasses with their respective standards. Ethanol produced through a fermentation process using spent hydrolysates with baker's yeast at pH 5.3 was found to be significant. The ethanol yield from brown seaweed spent biomass and red seaweed spent biomass was observed to be 0.011 g g⁻¹ and 0.02 ± 0.003 g g⁻¹ respectively, when compared with YPD (0.42 ± 0.03 g g⁻¹) and d-galactose (0.37 ± 0.04 g g⁻¹) as standard on day 4. The present study revealed the possibility of effective utilization of spent biomass from seaweed industry for ethanol production.     

Energy self-sufficient production of bioethanol from a mixture of hemp straw and triticale seeds: Life-cycle analysis

Industrial hemp shows exceptional potential for cellulosic ethanol production, especially regarding yields per hectare, costs and environmental impact. Additionally, co-products, such as high-value food-grade oil, increase the value of this plant. In this work, hemp straw was steam-exploded for 45 min at 155 °C and hydrolysed with a cellulase/xylanase mixture. Up to 0.79 g g⁻¹ of cellulose was degraded and subsequent simultaneous-saccharification-and-fermentation with added triticale grist resulted in >0.90 g g⁻¹ fermentation of cellulose. Hemp straw is very suitable, as it contains 0.63 g g⁻¹ of cellulose and only 0.142 g g⁻¹ of hemicellulose.A 2000 m³ a⁻¹ ethanol biorefinery requires a land use of 3 km² each for hemp and for triticale. A total of 2630 kg ethanol and 150 kg hemp oil can be gained from 1 ha. Slurry and triticale straw serve as raw material for the biogas fermenter or as animal feed. Biogas supplies thermal and electric energy in combined heat and power. Ethanol will remain at 0.66 € dm⁻³ based on market prices. In addition, data have been calculated for market prices plus and minus 30% market prices (0.51–0.81 € dm⁻³). Carbon dioxide (CO₂) abatement for ethanol achieves 121 g MJ⁻¹ CO_2eq for a combined ethanol/biogas plant. The CO₂ abatement costs vary from 38 € to 262 € t⁻¹ CO_2eq.     

Ethanol production from enzymatic hydrolysis of sugarcane bagasse pretreated with lime and alkaline hydrogen peroxide

In this work we evaluated ethanol production from enzymatic hydrolysis of sugarcane bagasse. Two pretreatments agents, lime and alkaline hydrogen peroxide, were compared in their performance to improve the susceptibility of bagasse to enzymatic action. Mild conditions of temperature, pressure and absence of acids were chosen to diminish costs and to avoid sugars degradation and consequent inhibitors formation. The bagasse was used as it comes from the sugar/ethanol industries, without grinding or sieving, and hydrolysis was performed with low enzymes loading (3.50 FPU g⁻¹ dry pretreated biomass of cellulase and 1.00 CBU g⁻¹ dry pretreated biomass of ??-glucosidase). The pretreatment with alkaline hydrogen peroxide led to the higher glucose yield: 691 mg g⁻¹ of glucose for pretreated bagasse after hydrolysis of bagasse pretreated for 1 h at 25 °C with 7.35% (v/v) of peroxide. Fermentation of the hydrolyzates from the two pretreatments were carried out and compared with fermentation of a glucose solution. Ethanol yields from the hydrolyzates were similar to that obtained by fermentation of the glucose solution. Although the preliminary results obtained in this work are promising for both pretreatments considered, reflecting their potential for application, further studies, considering higher biomass concentrations and economic aspects should be performed before extending the conclusions to an industrial process.     

Fed batch enzymatic saccharification of newspaper cellulosics improves the sugar content in the hydrolysates and eventually the ethanol fermentation by Saccharomyces cerevisiae

The newspaper is comprised of (w w^?1) holocellulose (70.0%) with substantial amount of lignin (16.0%). Bioconversion of the carbohydrate component of newspaper to sugars by enzymatic saccharification, and its fermentation to ethanol was investigated. Of various enzymatic treatments using cellulase, xylanase and laccase, cellulase enzyme system was found to deink the newspaper most efficiently. The saccharification of deinked paper pulp using enzyme cocktail containing exoglucanase (20 U g^?1), β-glucosidase (60 U g^?1) and xylanase (80 U g^?1) resulted in 59.8% saccharification. Among additives, 1% (v v^?1) Tween 80 and 10 mol m^?3 CoCl₂ improved the enzymatic hydrolysis of newspaper maximally, releasing 14.64 g L^?1 sugars. The fed batch enzymatic saccharification of the newspaper increased the sugar concentration in hydrolysate from 14.64 g L^?1 to 38.21 g L^?1. Moreover, the batch and fed batch enzymatic hydrolysates when fermented with Saccharomyces cerevisiae produced 5.64 g L^?1 and 14.77 g L^?1 ethanol, respectively.     

Residue of dates from the food industry as a new cheap feedstock for ethanol production

Syrup resulting from date by-products constitutes a favorable medium for yeast development, owing to its sugar composition; it was hence tested for ethanol production. Three yeasts, Saccharomyces cerevisiae, Zygosaccharomyces rouxii and Candida pelliculosa, were selected for ethanol production on dates syrup. In batch fermentation, the ethanol concentration depended on the initial sugar concentration and the yeast strain. For an initial sugar concentration of 174.0 ± 0.2 kg m⁻³, maximum ethanol concentration was 63.0 ± 0.1 kg m⁻³ during S. cerevisiae growth, namely higher than the amounts achieved during Z. rouxii and C. pelliculosa growth, 33.0 ± 2.0 kg m⁻³ and 41.0 ± 0.3 kg m⁻³ respectively. Contrarily, only Z. rouxii was able to grow on 358.0 ± 1.0 kg m⁻³ initial sugar amount, resulting in 55.0 ± 1.0 kg m⁻³ ethanol produced.     

Lignocellulosic ethanol production employing immobilized Saccharomyces cerevisiae in packed bed reactor

Most of ethanol production processes are limited by lower ethanol production rate and recyclability problem of ethanologenic organism. In the present study, immobilized co-fermenting Saccharomyces cerevisiae GSE1618 was employed for ethanol fermentation using rice straw enzymatic hydrolysate in a packed bed reactor (PBR). The immobilization of S. cerevisiae was performed by entrapment in Ca-alginate for optimization of ethanol production by varying alginic acid concentration, bead size, glucose concentration, temperature and hardening time. Remarkably, extra hardened beads (EHB) immobilized with S. cerevisiae could be used up to repeated 40 fermentation batches. In continuous PBR, maximum 81.82 g L⁻¹ ethanol was obtained with 29.95 g L⁻¹ h⁻¹ productivity with initial glucose concentration of 180 g L⁻¹ in feed at dilution rate of 0.37 h⁻¹. However, maximum ethanol concentration of 40.33 g L⁻¹ (99% yield) with 24.61 g L⁻¹ h⁻¹ productivity was attained at 0.61 h⁻¹ dilution rate in fermentation of un-detoxified rice straw enzymatic hydrolysate (REH). At commercial scale, EHB has great potential for continuous ethanol production with high productivity using lignocellulosic hydrolysate in PBR.     

Industrial sugar beets to biofuel: Field to fuel production system and cost estimates

Specialized varieties of sugar beets (Beta vulgaris L.) may be an eligible feedstock for advanced biofuel designation under the USA Energy Independence and Security Act of 2007. These non-food industrial beets could double ethanol production per hectare compared to alternative feedstocks. A mixed-integer mathematical programming model was constructed to determine the breakeven price of ethanol produced from industrial beets, and to determine the optimal size and biorefinery location. The model, based on limited field data, evaluates Southern Plains beet production in a 3-year crop rotation, and beet harvest, transportation, and processing. The optimal strategy depends critically on several assumptions including a just-in-time harvest and delivery system that remains to be tested in field trials. Based on a wet beet to ethanol conversion rate of 110 dm³ Mg⁻¹ and capital cost of 128 M$ for a 152 dam³ y⁻¹ biorefinery, the estimated breakeven ethanol price was 507 $ m⁻³. The average breakeven production cost of corn (Zea mays L.) grain ethanol ranged from 430 to 552 $ m⁻³ based on average net corn feedstock cost of 254 and 396 $ m⁻³ in 2014 and 2013, respectively. The estimated net beet ethanol delivered cost of 207 $ m⁻³ was lower than the average net corn feedstock cost of 254–396$ m⁻³ in 2013 and 2014. If for a mature industry, the cost to process beets was equal to the cost to process corn, the beet breakeven ethanol price would be $387 m^-3 (587 $ m⁻³ gasoline equivalent).     

Biological hydrogen production from corn stover by moderately thermophile Thermoanaerobacterium thermosaccharolyticum W16

This study addressed the utilization of an agro-waste, corn stover, as a renewable lignocellulosic feedstock for the fermentative H₂ production by the moderate thermophile Thermoanaerobacterium thermosaccharolyticum W16. The corn stover was first hydrolyzed by cellulase with supplementation of xylanase after delignification with 2% NaOH. It produced reducing sugar at a yield of 11.2 g L⁻¹ glucose, 3.4 g L⁻¹ xylose and 0.5 g L⁻¹ arabinose under the optimum condition of cellulase dosage 25 U g⁻¹ substrate with supplement xylanase 30 U g⁻¹ substrate. The hydrolyzed corn stover was sequentially introduced to fermentation by strain W16, where, the cell density and the maximum H₂ production rate was comparable to that on simulated medium, which has the same concentration of reducing sugars with hydrolysate. The present results suggest a promising combined hydrogen production process from corn stover with enzymatic hydrolysis stage and fermentation stage using W16.     

Production of bio-ethanol from three varieties of dates

In this work, production of bio-ethanol from three varieties of dates (Kunta, Eguoua and Bouhatem) produced in the region of Gabes-Tunisa was studied. A comparison between soxhlet and solvent extraction of a juice obtained from the dates was made. The alcoholic fermentation of this juice by Saccharomyces cerevisiae was investigated under sugar concentration near 200 g L⁻¹ at 30 °C and natural pH. The obtained results showed that all the tested varieties allowed producing ethanol with a concentration around 25% (V/V). Moreover the yeast used in the fermentation process is capable of producing alcohol even at a pH of 3.8.     

Evaluation of fuel ethanol production from aqueous ammonia-treated rice straw via simultaneous saccharification and fermentation

Rice straw (RS) has been considered a promising feedstock for ethanol production in Asia. However, the recalcitrance of biomass, particularly the presence of lignin, hinders the enzymatic saccharification of polysaccharides in RS and consequently decreases the ethanol yield. Here, we used aqueous ammonia pretreatment to remove lignin from RS (aRS). The reaction conditions were a solid:liquid ratio of 1:12, an ammonia concentration of 27% (w w⁻¹), room temperature, and a 2-week incubation. We evaluated enzymatic digestibility and the ethanol production yield. A 42% reduction in lignin content increased the glucan conversion of aRS to glucose from 20 to 71% using a combination of Cellic Ctec2 cellulases and Cellic Htec2 xylanases at enzyme loads of 15 FPU +100 XU g⁻¹ solid. Scanning electron microscopy highlighted the extensive removal of external fibres and increased porosity of aRS, which aided the accessibility of cellulose for enzymes. Using the same enzyme dosage and a solid load of 100 g L⁻¹, simultaneous saccharification and fermentation using a monoculture of Saccharomyces cerevisiae and co-culture with Candida tropicalis yielded ethanol concentrations of 22 and 25 g L⁻¹, corresponding to fermentation efficiencies of 96 and 86% fermentation, respectively. The volumetric ethanol productivities for these systems were 0.45 and 0.52 g L⁻¹ h⁻¹. However, the ethanol yield based on the theoretical glucose and xylose concentrations was lower for the co-culture (0.44 g g⁻¹) than the monoculture (0.49 g g⁻¹) due to the low xylose consumption. Further research should optimise fermentation variables or select/improve microbial strains capable of fermenting xylose to increase the overall ethanol production yield.     

Efficient ethanol production from inulin by two-stage aerate strategy

A major concern for ethanol production from inulin-containing materials, is the higher unconverted sugar, which increases the cost of ethanol production and wastewater treatment. Some key factors, such as inulinase, biomass or aeration rates, were studied to solve the problems in the process of ethanol fermentation from inulin. It was showed that more inulinase and increasing inoculum size can shorten the fermentation time, but could not reduce residual sugars. Two-stage aerate strategy was developed to utilize the remained sugars: keep the aeration at 5 h⁻¹ at the first 12 h, and drop it to 1.2 h⁻¹. Under this condition, contradiction between fermentation time and high ethanol yield was solved (60 h and 0.43 g g⁻¹), and the final residual sugar concentration decreased to about 10 g L⁻¹ with 98 g L⁻¹ ethanol. The ethanol productivity was up to 1.63 g L⁻¹ h⁻¹, which is the highest productivity of ethanol fermentations from inulin-containing materials.     

Direct bioconversion of sorghum extract sugars to free fatty acids using metabolically engineered Escherichia coli strains: Value addition to the sorghum bioenergy crop

The unprecedented challenge of meeting the energy demand of growing economies has increased the need to produce hydrocarbon fuels using renewable sources. Among different platforms being researched these days, hydrocarbon biofuel and chemical production from free fatty acids (FFAs) have gained a lot of attention. The current study reports on value addition to sorghum energy crop through utilization of sorghum extract as a renewable carbon source for FFA production using genetically engineered Escherichia coli. In order to reduce the production cost of FFAs, direct sucrose utilizing E. coli strains were developed. The E. coli strain MG1655 with fadD mutant (named as ML103) either carrying the plasmid bearing the gene for acyl-ACP thioesterase (TE) from Ricinus communis (pXZ18) or a plasmid bearing a combination of the TE and the native (3R)-hydroxyacyl-ACP dehydrase gene (fabZ) (pXZ18Z) was modified to utilize sucrose by incorporating the pUR400 plasmid. The newly created strains utilized a mixture of pure sugars and sorghum extract efficiently. The 24 h pH adjusted culture of ML103 pXZ18Z pUR400 produced a maximum of 6.18 ± 0.52 g l⁻¹ from 30 g l⁻¹ of pure sugar mixture and 2.95 ± 0.04 g l⁻¹ with sorghum extract (15 g l⁻¹ equivalent sugar concentration). These data suggest that modified E. coli strains were capable of directly utilizing sucrose and produce FFAs from it. Successful demonstration of direct bioconversion of sorghum extract to FFA was validated as a possible value addition of the sorghum bioenergy crop.