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.     

Effect of Pr-Ca substitution on the transport and magnetic behavior of LaMnO3 perovskite

The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO₃ perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good example of these properties is (La_1−2x Pr _x Ca _x )MnO₃ (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T _c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for understanding the structural, transport and magnetic properties are discussed in detail.     

Cellulosic Films Obtained from the Treatment of Sugarcane Bagasse Fibers with N-methylmorpholine-N-oxide (NMMO)

Ethanol/water organosolv pulping was used to obtain sugarcane bagasse pulp that was bleached with sodium chlorite. This bleached pulp was used to obtain cellulosic films that were further evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). A good film formation was observed when temperature of 74 °C and baths of distilled water were used, which after FTIR, TGA, and SEM analysis indicated no significant difference between the reaction times. The results showed this to be an interesting and promising process, combining the prerequisites for a more efficient utilization of agro-industrial residues.     

Integrated processes for use of pulps and lignins obtained from sugarcane bagasse and straw

Sugarcane bagasse and straw can be converted into pulps, oils, controlled-release formulations, chelating agents, and composites. This article reviews bagasse and straw conversion efforts in Brazil. Laboratory-scale processes were developed aiming at the integral use of these biomass byproducts. Organosolv pulping and oxidation of lignin are the most promising processes for the rational use of sugarcane residues. Fungal pretreatment and spectroscopic characterization are also discussed.     

Xylanase and β-Xylosidase Production by <Emphasis Type="BoldItalic">Aspergillus ochraceus</Emphasis>: New Perspectives for the Application of Wheat Straw Autohydrolysis Liquor

The xylanase biosynthesis is induced by its substrate—xylan. The high xylan content in some wastes such as wheat residues (wheat bran and wheat straw) makes them accessible and cheap sources of inducers to be mainly applied in great volumes of fermentation, such as those of industrial bioreactors. Thus, in this work, the main proposal was incorporated in the nutrient medium wheat straw particles decomposed to soluble compounds (liquor) through treatment of lignocellulosic materials in autohydrolysis process, as a strategy to increase and undervalue xylanase production by Aspergillus ochraceus. The wheat straw autohydrolysis liquor produced in several conditions was used as a sole carbon source or with wheat bran. The best conditions for xylanase and β-xylosidase production were observed when A. ochraceus was cultivated with 1% wheat bran added of 10% wheat straw liquor (produced after 15 min of hydrothermal treatment) as carbon source. This substrate was more favorable when compared with xylan, wheat bran, and wheat straw autohydrolysis liquor used separately. The application of this substrate mixture in a stirred tank bioreactor indicated the possibility of scaling up the process to commercial production.     

Influence of pressure in ethanol/water pulping of sugarcane bagasse

The influence of the pressure in the ethanol/water pulping of sugarcane bagasse was studied using argon pressure varying from 0.5 to 1.5 MPa. The reaction volume and activation volume were studied. For the reaction volume, temperature and time were constant and pressure was varied, and for the activation volume, temperature was constant and pressure and time were varied. The degradation of cellulose was not promoted by the pressure with positive reaction volume (4100 cm³/mol). On the other hand, degradation of xylan (polyoses) and lignin was strongly favored by the pressure and reaction volume ranged from ?1000 to ?3000 cm³/mol.     

Development and Characterization of an Environmentally Friendly Process Sequence (Autohydrolysis and Organosolv) for Wheat Straw Delignification

The present work describes the delignification of wheat straw through an environmentally friendly process resulting from sequential application of autohydrolysis and organosolv processes. Wheat straw autohydrolysis was performed at 180°C during 30 min with a liquid–solid ratio of 10 (v/w); under these conditions, a solubilization of 44% of the original xylan, with 78% of sugars as xylooligosaccharides of the sum of sugars solubilized in the autohydrolysis liquors generated by the hemicellulose fraction hydrolysis. The corresponding solid fraction enrichment with 63.7% of glucan and 7.55% of residual xylan was treated with a 40% ethanol and 0.1% NaOH aqueous solution at a liquid–solid ratio of 10 (v/w), with the best results obtained at 180°C during 20 min. The highest lignin recovery, measured by acid precipitation of the extracted lignin, was 3.25 g/100 ml. The lignin obtained by precipitation was characterized by FTIR, and the crystallinity indexes from the native cellulose, the cellulose recovered after autohydrolysis, and the cellulose obtained after applying the organosolv process were obtained by X-ray diffraction, returning values of 21.32%, 55.17%, and 53.59%, respectively. Visualization of the fibers was done for all the processing steps using scanning electron microscopy.     

Cr(VI) Oxidation of Cholesterol—A Kinetic Study Using N-Cetylpicolinium Dichromates,A Class of Novel Phase Transfer Oxidants

Kinetics and Catalysis - Kinetic study of cholesterol oxidation has been studied using a series of N-cetylpicolinium dichromates (CPDC), a class of phase transfer oxidants, in acetic acid medium...     

Bleachability and characterization by fourier transform infrared principal component analysis of acetosolv pulps obtained from sugarcane bagasse

Sugarcane bagasse Acetosolv pulps were bleached by xylanase and the pulps classified by using Fourier transform infrared (FTIR) spectroscopy and principal component analysis (PCA). Pulp was treated with xylanase for 4–8 h with stirring at 30°C. Some samples were further extracted with NaOH for 1 h at 65°C. FTIR spectra were recorded directly from the dried pulp samples by using the diffuse reflectance technique. Reduction in kappa number of 69% was obtained after sequence xylanase (4 h)-alkaline extraction. During bleaching the viscosity decreased only 12%. FTIR-PCA showed that the first three principal components (PCs) explained more than 90% of the total variance of the pulp spectra. PC2×PC1 plot showed that the points related to pulps from sequence xylanase (4 h)-alkaline extraction are different from the other. This group isenlarged by plotting PC3×PC1 or PC3×PC2 containing all pulps submitted to alkaline extraction. PC2 and PC3 are the principal factor for differentiation of the pulps. These PCs suffer influence of the ester bands (1740 and 1244 cm⁻¹). On the other hand, the pulps bleached only with xylanase could not be differentiated from the nonbleached pulps.     

Bromelain Enzyme from Pineapple: In Vitro Activity Study under Different Micropropagation Conditions

The aim of this work was to evaluate the activity of bromelain in pineapple plants (Ananas comosus var. Comosus), Pérola cultivar, produced in vitro in different culture conditions. This enzyme, besides its pharmacological effects, is also employed in food industries, such as breweries and meat processing. In this work, the enzymatic activity was evaluated in the tissues of leaves and stems of plants grown in culture medium without plant growth regulator. The most significant levels of bromelain were observed in leaf tissue after 4?months of culture in vitro in medium with a filter paper bridge, followed by medium gelled by the agar. The results of this study, regarding the different structures of the pineapple (leaves and stems) in vitro showed that the activity of bromelain varied depending on the culture conditions, the time and structure of which was quantified, ensuring a viable strategy in the production of seedlings with high levels of bromelain in subsequent phases of micropropagation.