Ethanol-water pulp enzymatic pretreatment: chemical and FTIR-PCA analyses

Pulps obtained from ethanol/water cooking of sugarcane bagasse were treated at different times using xylanase enzyme obtained from Thermomyces lanuginosus IOC-4145 or commercially (Cartazyme HS, Sandoz Products Ltd.). The enzyme dosage was 18 IU per g of dry pulp and the time varied from 4 h to 12 h. When xylanase from T. lanuginosus was used, the kappa number and viscosity improved independently of the processing time used (4 h, 8 h, and 12 h). After chemical evaluation, the obtained pulps were classified using Fourier Transformed Infra-Red Spectroscopy and Principal Component Analysis. The results showed that the first three principal components explained more than 90 % of the total variance of the pulp spectra.FAPESP; CNPq

Studies of lignin and polysaccharides recovery from kraft liquor for biotechnological applications

According to the biorefinery concept, this study has the objective of evaluating alternatives for the valorization of all the kraft liquor fractions. This liquor consists mainly in lignin, cellulose and hemicellulose. Currently, cellulose pulp industries recover the cooking chemicals by burning and energy is introduced into the process. Sustainable development guidelines, regarding the costs and wastes reduction and biotechnology principles may present new solutions for the production of valuable products. In this study, two methods for the polysaccharides extraction, in three different pH conditions, are presented. The only difference between these methods is the solvent applied: ethanol and 1,4‐dioxane. All the samples were maintained 24 h at 298 K. After a filtration step, the solid fraction resultant from the ethanol treatment had a carbohydrate content of 40.51%, 44.64% and 49.53%, for pH values of 3, 4 and 6, respectively. The treatment with 1,4‐dioxane, reached the following values: 21.17%, 18.41% and 29.73% for the same pH values. These results were obtained with HPLC analysis after polysaccharides hydrolysis. Three unknown peaks were detected that we considered to be sugar derivative compounds. Thus, the polysaccharides contents, for both treatments, might actually be superior. Concerning to the product purity, the ethanol extraction revealed to be the less efficient. The lignin content in the solid fraction, ranged between 28% and 31%, with 1,4‐dioxane extraction, and between 40% and 50%, with ethanol. The lignin molecular weight was determined with GPC, after and before liquor pH lowering. Thereby, for pH 6, pH 4 and pH 3 the obtained MWs were: 2376 Da, 1477 Da and 3705 Da, respectively. The molecular weight increase may be due to the lignin repolymerization. These results suggest that the polysaccharides recovery and lignin molecular weight may be related. As the molecular weight increases or decreases, the polysaccharides percentage presents the same behavior, regardless of the product purity. The data obtained after FT‐IR analysis suggested that there was no significant modifications on lignin structure. Summarizing, these preliminary results indicate that there is a possibility of recovering the kraft liquor´s polysaccharide while the residual lignin can still be used for burning to energy recovery.Erasmus Mundus ‐ ISAC ProgramFundação para a Ciência e a Tecnologia (FCT)Millipore BrazilConselho Nacional de Desenvolvimento Científico e Tecnológico Brazil - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CNPq‐CAPES

Hydrothermal treatments of corn cob and hemicelluloses extraction

Corn cob samples were treated with water (autohydrolysis reaction) using a liquid to solid ratio of 10:1 w/w. The optimal condition for extraction of hemicelluloses was found at 185ºC for 30 min. This resulted in the release of 9.7% of hemicelluloses (% dry starting material), corresponding to the dissolution of 27.9% of the original hemicellulose. Chemical composition and physico-chemical properties of the samples were elucidated by a combination of sugar analyses and thermal analysis. The results showed that the treatment was effective on the extraction of hemicelluloses from corn cob and that the TGA analysis of xylan from birch wood was found to be initially degraded at about 220 ºC whereas hemicelluloses from corn cob would be degraded at about 225 ºC.Fundação para a Ciência e a Tecnologia (FCT).Erasmus Programme (Turkey)

Hemicelluloses fractions extraction of corn residue

Fundação para a Ciência e a Tecnologia (FCT)Erasmus Programm

Bioethanol production from hydrothermal pretreated wheat straw by a flocculating Saccharomyces cerevisiae strain : effect of process conditions

Wheat straw is nowadays being considered a potential lignocellulose raw material for fuel ethanol production of second generation and as an alternative to conventional fuel ethanol production from cereal crops. In the present study, hydrothermal pretreated wheat straw with high cellulose content (>60%) at 180 °C for 30 min was used as substrate in simultaneous saccharification and fermentation (SSF) process for bioethanol production using a thermotolerant flocculating strain of Saccharomyces cerevisiae CA11. In order to evaluate the effects of temperature, substrate concentration (as effective cellulose) and enzyme loading on: (1) ethanol conversion yield, (2) ethanol concentration, and (3) CO2 concentration a central composite design (CCD) was used. Results showed that the ethanol conversion yield was mainly affected by enzyme loading, whereas for ethanol and CO2 concentration, enzyme loading and substrate concentration were found to be the most significant parameters. The highest ethanol conversion yield of 85.71% was obtained at 30 °C, 2% substrate and 30 FPU of enzyme loading, whereas the maximum ethanol and CO2 concentrations (14.84 and 14.27 g/L, respectively) were obtained at 45 °C, 3% substrate and 30 FPU of enzyme loading, corresponding to an ethanol yield of 82.4%, demonstrating a low enzyme inhibition and a good yeast performance during SSF process. The high cellulose content obtained in hydrothermal pretreatment and the use of a thermotolerant flocculating strain of S. cerevisiae in SSF suggest as a very promising process for bioethanol production.The authors H.A. Ruiz thanks to Mexican Science and Technology Council (CONACYT, Mexico) for PhD fellowship support (CONACYT grant number: 213592/308679) and L. Lima gratefully acknowledges the Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) for PhD fellowship support (SFRH/BDE/15637/2006), also to Professor Juan Carlos Parajo, Patricia Gullon and Beatriz Gullon from University of Vigo, for the assistance in the materials preparation under hydrothermal processing and Francisco Pereira for yeast preparation analysis techniques

Pretreatment of brewers' spent grains for cellulases production by Aspergillus niger van Tieghem

Successful utilization of cellulosic materials as a renewable carbon source is dependent on the development of economically feasible process technologies both for the production of biomass-degrading enzymes, and for the enzymatic hydrolysis of cellulosic materials to low molecular weight products. Significant cost reduction is required in order to enhance the commercial viability of cellulase production technology and biomass pretreatment can be an essential processing step for this purpose. Thus, the aim of this work was to evaluate the performance of pretreated brewers´ spent grains on the improvement of cellulases production by A. niger van Tieghem. For this, brewers´ spent grains was submitted to autohydrolysis treatment. Initially, the material was dried, milled and sieved (1.0 mm screen). Water was added to the sample in a closed and pressurized vessel (solid/liquid ratio 1:10 w/v), and the system heated to 180, 190 or 200ºC for 10, 35 or 50 min. The liquor obtained (hemicelluloses fraction) was separated from the solids (cellulose/lignin) by filtration and both fractions were used together or not as carbon source on fermentation: 1% (w/v) treated solid fraction; 1% (w/v) solids plus 10% (v/v) liquor, or only liquor. Carboxymethylcellulose, avicel and untreated brewers´ spent grains were used as control. The inocullum was done in Mandels medium and the cultivation conditions were 30ºC/100 rpm for 6 days. Carboxymethylcellulase (CMCase) and avicelase were assayed by DNS using 1% (w/v) carboxymethylcellulose in sodium acetate buffer, pH 4.0 and 1% (w/v) avicel in the same buffer, pH 5.0, respectivelly, while β-glucosidase was detected by p-nitrophenolate released using 5 mM pnp-β-D-glucoside in sodium citrate buffer, pH 4.5. One unit of enzymatic activity was defined as the amount that liberated 1 μmol of product per minute on assay conditions. The results showed that the liquor obtained at 190ºC/50 min autohydrolysis was quite favorable to CMCase and avicellase production, since the enzyme production was significantly higher than with other sources. However, the effect of the treatment on β-glucosidase production was not as significant as the control. These results show that by using autohydrolysis liquor as an alternative substrate, the performance of the bioprocess for cellulase production can be improved

Evaluation of a hydrothermal process for pretreatment of wheat straw : effect of particle size and process conditions

Hydrothermal processes are an eco-friendly processes that provide an interesting alternative for chemical utilization of lignocellulosic materials, in which water and crop residues are the only reagents. In this work the effect of process conditions (size distribution of the wheat straw, temperature and time) was evaluated against production of fermentable products. RESULTS: The use of milled wheat straw fractions as a raw material containing blends of different particle size distribution showed that the latter had an influence on the final sugars in the hydrolysate. Improved values of glucose (21.1%) and xylose yields (49.32%) present in the hydrolysate were obtained with treatment severity factors of 2.77 and 3.36, respectively. Mathematical models were developed aimed at establishing the effect of process conditions on monosaccharide concentration and its degradation in the liquor. CONCLUSION: This work shows that the use of wheat straw blends with various particle sizes has a significant effect on the extraction of fermentable products. The effect of treatment severity, which takes into account both processing time and temperature was also evaluated. These results are of importance for process design.ALBAN programm