Magnetic characterization of ferrihydrite nanoparticles synthesized by hydrolysis of Fe metal-organic precursor

We investigate the formation of ferrihydrite nanoparticles (NPs) by hydrolysis of the Fe(III) alkoxide Fe(O(t)Bu)(3). Controlled amounts of water, up to 3.0 vol%, were added to the precursor solution yielding a series of hydrolyzed samples ranging from P0.0 (the unreacted precursor) to P3.0. X-ray diffraction (XRD) analysis evidenced the formation of high-crystalline ferrihydrite NP in sample P3.0, with grain size estimate of about 3.2 nm. The transition from the molecular precursor to the formation of crystalline magnetic NPs was followed through magnetization measurements M(T) and M(H), as well as Mossbauer spectroscopy (MS). M(T) measurements indicate a paramagnetic (PM) behavior for sample P0.0, characteristic of binuclear Fe-O-Fe units, which evolves to a superparamagnetic (SPM) behavior, with an energy barrier for the blocking process estimated for sample P3.0 as E(a) = 4.9 x 10(-21) J (E(a)/k(B) = 355 K), resulting in a high effective anisotropy constant K(eff) = 290 kJ/m(3). Magnetization loops at 5 K progressively change from PM-like to ferromagnetic-like shape upon increasing the hydrolysis process, although hysteresis (H(c) approximate to 500 Oe) only is apparent for P2.0 and higher. MS spectra at room temperature are PM/SPM doublets for all samples, while the MS spectra at T = 4.2 K reveal increasingly well-defined magnetic ordering as hydrolysis of the precursor stepwise progresses until well-crystallized ferrihydrite particles are formed. (C) 2008 Elsevier B.V. All rights reserved.

Optimization of acid hydrolysis from the hemicellulosic fraction of Eucalyptus grandis residue using response surface methodology

Biotechnological conversion of biomass into fuels and chemicals requires hydrolysis of the polysaccharide fraction into monomeric sugars. Hydrolysis can be performed enzymatically and with dilute or concentrate mineral acids. The present study used dilute sulfuric acid as a catalyst for hydrolysis of Eucalyptus grandis residue. The purpose of this paper was to optimize the hydrolysis process in a 1.41 pilot-scale reactor and investigate the effects of the acid concentration, temperature and residue/acid solution ratio on the hemicellulose removal and consequently on the production of sugars (xylose, glucose and arabinose) as well as on the formation of by-products (furfural, 5-hydroxymethylfurfural and acetic acid). This study was based on a model composition corresponding to a 2 3 orthogonal factorial design and employed the response surface methodology (RSM) to optimize the hydrolysis conditions, aiming to attain maximum xylose extraction from hemicellulose of residue. The considered optimum conditions were: H2SO4 concentration of 0.65%, temperature of 157 degrees C and residue/acid solution ratio of 1/8.6 with a reaction time of 20 min. Under these conditions, 79.6% of the total xylose was removed and the hydrolysate contained 1.65 g/l glucose, 13.65 g/l xylose, 1.55 g/l arabinose, 3.10 g/l acetic acid, 1.23 g/l furfural and 0.20 g/l 5-hydroxymethylfurfural. (c) 2006 Published by Elsevier Ltd.

A CALORIMETRIC STUDY OF THE ULTRASOUND-STIMULATED HYDROLYSIS OF SOLVENTLESS TEOS-WATER MIXTURES

The kinetics of ultrasound-stimulated and HCl-catalyzed hydrolysis of solventless TEOS-water mixtures was studied as a function of temperature ranging from 10 degrees C up to 65 degrees C by means of flux calorimetry measurements. A specially designed device was utilized for this purpose. The exothermic peak arising few minutes after sonication began has been attributed mainly to the hydrolysis reaction. The overall hydrolysis process, which was measured through the irradiation time up to the hydrolysis peak, was found to be thermally activated, with an apparent activation energy Delta E = 36.4 kJ/mol. The alcohol produced at the early hydrolysis due to sonication seems to further enhance the reaction, via a parallel autocatalytic path, which is controlled by a faster pseudo second order rate constant (k'). Our modeling yielded k' = 6.3 x 10(-2) M(-1) min(-1) at 20 degrees C, which is in a reasonable agreement with the literature, and an activation energy Delta E = 40.4 kJ/mol for the specific process of hydrolysis in presence of alcohol.

Solid-state hydrolysis of postconsumer polyethylene terephthalate after plasma treatment

Plasma treatments were applied on the surface of postconsumer polyethylene terephthalate (PET) bottles to increase their wettability and hasten the subsequent hydrolysis process. Sixty-four treatments were tested by varying plasma composition (oxygen and air), power (25-130 W), pressure (50-200 mTorr), and time (1 and 5 min). The best treatment was the one applied in air plasma at 130 W and 50 mTorr for 5 min, as it provided the lowest contact angle, 9.4°. Samples of PET before and after the optimized plasma condition were subjected to hydrolysis at 205°C. Although the treatment changed only a thin surface layer, its influence was evident up to relatively high conversion rates, as the treated samples presented more than 40% higher conversion rates than the untreated ones after 2 h of reaction. Infrared spectroscopy showed that the terephthalic acid obtained from 99% of depolymerization was similar to the commercial product used in PET synthesis. © 2012 Wiley Periodicals, Inc.

Aqueous two-phase extraction using thermoseparating copolymer: a new system for phenolic compounds removal from hemicelullosic hydrolysate

BACKGROUND: The hydrolysis of hemicellulosic material can provide liquor with high xylose concentration (which can be used as a fermentation medium) and phenolic compounds (Phs), potentially immunostimulating compounds. However, these hydrolysates must be detoxified in order to remove the Phs that can act as inhibitors in bioconversions. RESULTS: Aqueous two-phase systems composed of thermoseparating copolymers were used for rice straw hydrolysate detoxification. The hydrolysis process was able to promote chemical breakdown of 85% of the total hemicellulose content, 14% of the cellulose, and 2% of the lignin. The hydrolysate obtained contained 19.7 g L-1 of xylose and several phenolic compounds, such as vanillin, vanillic acid, ferullic acid, etc. The phenolics extraction was studied as a function of copolymer molar mass (1100 g mol(-1), 2000 g mol(-1) and 2800 g mol(-1)), their percentages (from 5% to 50%) and Phs initial concentration. Phenolic compounds extraction of around 80% was obtained under the following conditions: 20% (w/w) and 35% (w/w) copolymer 1100 g mol-1, 35% (w/w) copolymer 2000 g mol(-1) and 35% (w/w) copolymer 2800 g mol(-1) at 25 degrees C. CONCLUSIONS: The results demonstrated the viability of this method for the removal of Phs from rice straw hydrolysate, which has potential uses in bioconversion processes. (c) 2007 Society of Chemical Industry.

Produção de óleos e fillers proteicos a partir da raspa tripa da indústria de curtumes

A indústria de curtumes é fortemente geradora de resíduos sólidos e águas residuais pelo que a necessidade de criar alternativas para a sua valorização e minimização é premente e constante. Este trabalho teve, como principal objectivo, o aproveitamento da raspa tripa, resíduo da indústria de curtumes. Para tal, a raspa tripa foi sujeita a um processo de hidrólise térmica e/ou enzimática para obtenção de gordura e hidrolisado proteico. Na hidrólise da raspa tripa foi estudada a influência de vários factores como a quantidade de enzima e de água, a temperatura e o tempo. Constatou-se que foi para a temperatura de 60ºC, um tempo de quatro horas, uma quantidade de 2% de enzima e 100% de água, relativamente à massa de raspa utilizada, que se obteve o melhor resultado com um rendimento de extracção de 93%. A partir da gordura obtida foram produzidos óleos por sulfatação e sulfitação, designados por óleos sulfatados e sulfitados, respectivamente. O hidrolisado proteico obtido foi concentrado por evaporação para aumentar o seu teor de sólidos totais. Com este foram produzidos gluproteicos e fillers, por acção de glutaraldeído e do efeito sinérgico de outros produtos. Os óleos, o hidrolisado concentrado e seus derivados foram testados no processo de engorduramento e recurtume do couro. A avaliação dos resultados foi realizada por comparação dos resultados dos testes físico-mecânicos das amostras de pele obtidas com valores de referência e por comparação com um ensaio padrão em que se utilizaram produtos de referência do mercado. Os resultados foram muitos satisfatórios visto que foram superiores aos valores de referência e também superiores aos valores obtidos para o padrão salvo raras excepções. Reconheceu-se assim a aplicabilidade destes produtos no processo de recurtume e engorduramento que também corresponderam no que respeita a características importantes do couro como a firmeza de flor e o toque. No decorrer do trabalho constatou-se que as peles tratadas com hidrolisado proteico apresentavam uma cor mais intensa, pelo que se efectuou um estudo de colorimetria através do método CIELAB. Comprovou-se que o hidrolisado proteico e os gluproteicos quando utilizados no processo de recurtume, por substituição do Fortan A40, intensificam a cor da pele. A valorização da raspa tripa resulta numa dupla vantagem para a indústria dos curtumes. Se por um lado diminui o impacto ambiental que esta origina, por outro lado possibilita a produção de produtos que podem ser substitutos de outros produtos químicos que têm que ser adquiridos por esta indústria.

Biomassahydrolysaattien puhdistus uutolla

Lignoselluloosasta koostuvasta biomassasta valmistetaan hydrolysoimalla sokereita, jotka jatkojalostetaan fermentoimalla bioetanoliksi. Bioetanolia käytetään fossiilisten polttoaineiden korvaajana esimerkiksi ajoneuvoissa. Bioetanolin valmistuksessa pyritään mahdollisimman hyvään saantoon, jotta sen valmistus olisi taloudellisesti kannattavaa. Hydrolyysin aikana syntyy sokerien lisäksi orgaanisia happoja, furaanin johdannaisia sekä fenolisia yhdisteitä. Yleisimpiä syntyviä yhdisteitä ovat muun muassa etikkahappo, furfuraali ja hydroksimetyylifurfuraali. Nämä yhdisteet haittaavat sokerien fermentointiprosessia ja pienentävät etanolin saantoa. Fermentointiprosessia haittaavien yhdisteiden poistoon hydrolysaattiliuoksesta voidaan käyttää esimerkiksi haihdutusta, membraanierotusta, adsorptiota, saostusta, sekä uuttoa. Tämän työn tarkoituksena oli tutkia leikkaussekoittimen soveltuvuutta biomassahydrolysaatin epäpuhtauksien erotukseen. Lisäksi kirjallisuusosassa on esitetty hydrolysointiprosessissa syntyviä haitta-aineita ja niiden erotusmenetelmiä.

Chromatographic recovery of chemicals from acidic biomass hydrolysates

Lignocellulosic biomasses (e.g., wood and straws) are a potential renewable source for the production of a wide variety of chemicals that could be used to replace those currently produced by petrochemical industry. This would lead to lower greenhouse gas emissions and waste amounts, and to economical savings. There are many possible pathways available for the manufacturing of chemicals from lignocellulosic biomasses. One option is to hydrolyze the cellulose and hemicelluloses of these biomasses into monosaccharides using concentrated sulfuric acid as catalyst. This process is an efficient method for producing monosaccharides which are valuable platforn chemicals. Also other valuable products are formed in the hydrolysis. Unfortunately, the concentrated acid hydrolysis has been deemed unfeasible mainly due to high chemical consumption resulting from the need to remove sulfuric acid from the obtained hydrolysates prior to the downstream processing of the monosaccharides. Traditionally, this has been done by neutralization with lime. This, however, results in high chemical consumption. In addition, the by-products formed in the hydrolysis are not removed and may, thus, hinder the monosaccharide processing. In order to improve the feasibility of the concentrated acid hydrolysis, the chemical consumption should be decreased by recycling of sulfuric acid without neutralization. Furthermore, the monosaccharides and the other products formed in the hydrolysis should be recovered selectively for efficient downstream processing. The selective recovery of the hydrolysis by-products would have additional economical benefits on the process due to their high value. In this work, the use of chromatographic fractionation for the recycling of sulfuric acid and the selective recovery of the main components from the hydrolysates formed in the concentrated acid hydrolysis was investigated. Chromatographic fractionation based on the electrolyte exclusion with gel type strong acid cation exchange resins in acid (H+) form as a stationary phase was studied. A systematic experimental and model-based study regarding the separation task at hand was conducted. The phenomena affecting the separation were determined and their effects elucidated. Mathematical models that take accurately into account these phenomena were derived and used in the simulation of the fractionation process. The main components of the concentrated acid hydrolysates (sulfuric acid, monosaccharides, and acetic acid) were included into this model. Performance of the fractionation process was investigated experimentally and by simulations. Use of different process options was also studied. Sulfuric acid was found to have a significant co-operative effect on the sorption of the other components. This brings about interesting and beneficial effects in the column operations. It is especially beneficial for the separation of sulfuric acid and the monosaccharides. Two different approaches for the modelling of the sorption equilibria were investigated in this work: a simple empirical approach and a thermodynamically consistent approach (the Adsorbed Solution theory). Accurate modelling of the phenomena observed in this work was found to be possible using the simple empirical models. The use of the Adsorbed Solution theory is complicated by the nature of the theory and the complexity of the studied system. In addition to the sorption models, a dynamic column model that takes into account the volume changes of the gel type resins as changing resin bed porosity was also derived. Using the chromatography, all the main components of the hydrolysates can be recovered selectively, and the sulfuric acid consumption of the hydrolysis process can be lowered considerably. Investigation of the performance of the chromatographic fractionation showed that the highest separation efficiency in this separation task is obtained with a gel type resin with a high crosslinking degree (8 wt. %); especially when the hydrolysates contain high amounts of acetic acid. In addition, the concentrated acid hydrolysis should be done with as low sulfuric acid concentration as possible to obtain good separation performance. The column loading and flow rate also have large effects on the performance. In this work, it was demonstrated that when recycling of the fractions obtained in the chromatographic fractionation are recycled to preceding unit operations these unit operations should included in the performance evaluation of the fractionation. When this was done, the separation performance and the feasibility of the concentrated acid hydrolysis process were found to improve considerably. Use of multi-column chromatographic fractionation processes, the Japan Organo process and the Multi-Column Recycling Chromatography process, was also investigated. In the studied case, neither of these processes could compete with the single-column batch process in the productivity. However, due to internal recycling steps, the Multi-Column Recycling Chromatography was found to be superior to the batch process when the product yield and the eluent consumption were taken into account.

Characterization of a hydrolyzed oil obtained from fish waste for nutraceutical application

The fish industry generates high volume of waste from fish oil that can have the extraction of its lipids used as nutraceuticals and foods. The objective of this study was to produce unsaturated fatty acids from industrialized fish oil by means of a differentiated hydrolysis process. The samples used were crude fish oil obtained from Campestre industry and characterized through physical-chemical parameters, according to AOCS: acidity, peroxide, saponification, iodine and percentage of free fatty acids and also obtained the fatty acid profile through derivatization method for gas chromatography. The results obtained for the oleochemical indices for refined oil were similar to the data found on the literature. The content of polyunsaturated fatty acids (PUFA) was found of 32,78%, with 9,12% of docosahexaenoic (DHA) and 10,36% of eicosapentaenoic (EPA), regarding monounsaturated fatty acids (MUFA) content was of 30,59% in the hydrolyzed fish oil in relation to refined (20,06%). Thus, it can be concluded that the hydrolysis process used for oils from fish-waste was satisfactory on the production of absolute yield of lipids in the process and significant preservation on the percentages of EPA and DHA, interesting on the production of nutraceuticals and nutrition of aquatic animals, including shrimp in captivity.

“Studies on glucose tolerant β-glucosidases from a novel Byssochlamys fulva and their applications in biomass to ethanol conversion”

Beta-glucosidases are critical enzymes in biomass hydrolysis process and is important in creating highly efficient enzyme cocktails for the bio-ethanol industry. Among the two strategies proposed for overcoming the glucose inhibition of commercial cellulases, one is to use heavy dose of BGL in the enzyme blends and the second is to do simultaneous saccharification and fermentation where glucose is converted to alcohol as soon as it is being generated. While the former needs extremely high quantities of enzyme, the latter is inefficient since the conditions for hydrolysis and fermentation are different. This makes the process technically challenging and also in this case, the alcohol generation is lesser, making its recovery difficult. A third option is to use glucose tolerant β-glucosidases which can work at elevated glucose concentrations. However, there are very few reports on such enzymes from microbial sources especially filamentous fungi which can be cultivated on cheap biomass as raw material. There has been very less number of studies directed at this, though there is every possibility that filamentous fungi that are efficient degraders of biomass may harbor such enzymes. The study therefore aimed at isolating a fungus capable of secreting glucose tolerant β- glucosidase enzyme. Production, characterization of β-glucosidases and application of BGL for bioethanol production were attempted.

Revaloració de la fracció cel·lular de la sang de porc procedent d'escorxadors industrials

La sang de porc és un subproducte comestible que es genera als escorxadors industrials durant el procés d'obtenció de la canal. Aquest subproducte es caracteritza per presentar una elevada càrrega contaminant i, degut a l'elevat volum que es genera, és necessari trobar estratègies que permetin la seva revaloració i aprofitament, a la vegada que disminuïm la contaminació ambiental i les despeses que es deriven del seu processament abans de l'abocament. La fracció cel·lular (FC) constitueix el 40 % de la sang de porc i conté principalment l'hemoglobina (Hb), que representa al voltant del 90 % del contingut en proteïna d'aquesta fracció (un 35 % aproximadament). L'elevat percentatge en proteïna i en ferro, i les seves bones propietats funcionals fan que l'aprofitament d'aquest subproducte com a primera matèria o ingredient de la indústria alimentària sigui una alternativa molt útil a l'hora de reduir les despeses de la indústria càrnia, sempre que es resolguin els problemes de l'enfosquiment i dels sabors estranys que pot conferir la FC quan s'addiciona a productes alimentaris. Una altra possible utilització de la FC és aprofitar les propietats colorants de l'Hb o del grup hemo, com a colorant d'origen natural en diversos productes alimentaris. Els objectius del present treball eren, en primer lloc, determinar les millors condicions d'aplicació del procés de conservació de la FC mitjançant la deshidratació per atomització i caracteritzar físico-químicament i microbiològica el concentrat d'Hb en pols. En segon lloc, avaluar l'eficàcia de diferents additius antioxidants i/o segrestants del ferro per prevenir l'enfosquiment que pateix la FC durant la deshidratació. En tercer lloc, aplicar tractaments d'altes pressions hidrostàtiques com a procés d'higienització i avaluar els efectes d'aquest tractament sobre la microbiota contaminant, el color i les propietats funcionals de la FC. Finalment, desenvolupar un procés d'obtenció d'hidrolitzats proteics descolorats a partir de l'Hb amb la finalitat d'utilitzar-los com a ingredients nutricionals i/o funcionals. La millor temperatura de deshidratació per atomització de la FC hemolitzada era 140ºC. La FC en pols presentava un contingut en humitat del 5,3 % i un percentatge de solubilitat proteica del 96 %. La deshidratació per atomització induïa canvis en l'estructura nativa de l'Hb i, per tant, un cert grau de desnaturalització que pot conduir a una disminució de les seves propietats funcionals. L'extracte sec de la FC en pols estava composat per un 94,6 % de proteïna, un 3 % de sals minerals i un 0,7 % de greix. Els valors CIE L*a*b* del color de la FC en pols eren força constants i reflectien el color vermell marró fosc d'aquesta, a causa de l'oxidació del ferro hèmic que es produeix durant la deshidratació. La càrrega contaminant de la FC fresca de la sang de porc era força elevada i el tractament d'hemòlisi amb ultrasons i la centrifugació posterior no produïen una reducció significativa de la microbiota contaminant, obtenint un producte amb uns recomptes microbiològics de l'ordre de 106 ufc·mL-1. La deshidratació per atomització produïa una disminució d'una unitat logarítmica dels recomptes totals de la FC hemolitzada. Tanmateix, el producte en pols encara reflectia l'elevada contaminació de la primera matèria, fet que condiciona negativament la seva utilització com a ingredient alimentari, a no ser que es millorin les condicions de recollida de la sang a l'escorxador o que aquesta o la FC es sotmeti a algun tractament d'higienització prèviament a la deshidratació. Les isotermes de sorció a 20ºC de la FC en pols tenien forma sigmoïdal i una histèresi estreta i llarga. L'equació GAB és un bon model matemàtic per ajustar les dades de sorció obtingudes experimentalment i determinar la isoterma d'adsorció de la FC deshidratada per atomització. El percentatge d'humitat de la FC deshidratada a 140ºC es corresponia a un valor d'aw a 20 ºC d'aproximadament el 0,16. Tenint en compte que estava per sota dels valors d'aw corresponents a la capa monomolecular, es pot garantir la conservació a temperatura ambient del producte, sempre que s'envasi en recipients tancats que no permetin l'entrada d'humitat de l'exterior. De l'estudi de la possible estabilització del color de la FC deshidratada per atomització mitjançant l'addició d'antioxidants i/o segrestants de ferro, es va observar que només l'àcid ascòrbic, la glucosa, l'àcid nicotínic i la nicotinamida, tenien efectes positius sobre el color del producte en pols. L'ascòrbic i la glucosa no milloraven la conservació del color de l'Hb però disminuïen l'enfosquiment que es produeix durant la deshidratació, amb la qual cosa es pot obtenir un producte en pols de color marró més clar. L'addició de dextrina o L-cisteïna no disminuïa l'enfosquiment ni evitava el canvi de color de l'Hb. L'àcid nicotínic i la nicotinamida protegien el color de l'Hb durant el procés de deshidratació i l'emmagatzematge de la FC en pols. Les millors condicions d'aplicació del tractament amb altes pressions hidrostàtiques (HHP) sobre la FC eren 400 MPa, a 20ºC, durant 15 minuts, perquè produïen una millora significativa de la qualitat microbiològica, no afectaven negativament al color, no comprometien gaire la solubilitat proteica l'Hb i, malgrat que produïen un augment de la viscositat, la FC romania fluida després del tractament. Aquest tractament permetia una reducció de la microbiota contaminant de la FC d'entre 2 i 3 unitats logarítmiques. L'aplicació de l'alta pressió i la posterior deshidratació per atomització permetien obtenir un producte en pols amb recomptes totals de l'ordre de 2,8 unitats logarítmiques. El color de la FC pressuritzada en pols era igual que el de la FC control deshidratada, perquè ambdues mostres presentaven la mateixa susceptibilitat a l'oxidació del grup hemo produïda per la deshidratació. L'alta pressió incrementava la susceptibilitat de l'Hb als efectes desnaturalitzants de la deshidratació, fonamentalment a pH 7 (PIE), ja que es va observar una disminució de la solubilitat proteica a pH neutre després dels 2 processos tecnològics. La FC en pols presentava una màxima capacitat escumant al PIE de l'Hb. L'aplicació del tractament HHP produïa una disminució de la capacitat escumant de la FC en pols, però no tenia efectes negatius sobre l'estabilitat de l'escuma formada. Tampoc es van observar efectes negatius del tractament HHP sobre l'activitat emulsionant de l'Hb. La màxima activitat emulsionant de l'Hb s'aconseguia amb una concentració de FC en pols de l'1,5 % a pH 7 i de l'1 % a pH 4,5. Les pastes obtingudes per escalfament de la FC presentaven característiques molt diferenciades depenent del pH. A pH neutre es formaven unes pastes dures i consistents, mentre que a pH àcid les pastes eren poc consistents, molt adhesives i més elàstiques que les anteriors. Aquestes tenien una capacitat de retenció d'aigua molt superior que les de pH 7, en les quals l'aigua quedava retinguda per capil·laritat. La textura i capacitat de retenció d'aigua de les pastes tampoc eren afectades pel tractament HHP. El tractament HHP incrementava l'activitat de la Tripsina sobre l'Hb quan el substrat i l'enzim es tractaven conjuntament i afavoria el procés d'obtenció d'hidrolitzats descolorats a partir de la FC, la qual cosa permetia assolir el mateix grau de descoloració amb una dosi d'enzim inferior. El tractament d'hidròlisi de la FC amb la utilització combinada de Tripsina seguida d'un tractament amb Pepsina permetia l'obtenció d'un hidrolitzat proteic d'Hb descolorat i hidrolitzava completament la globina, donant lloc a 2 pèptids de 10,8 i 7,4 KDa. Val a dir que també produïa un 60 80 % de nitrogen soluble en TCA, constituït fonamentalment per pèptids petits i aminoàcids lliures. Els hidrolitzats trípsics i pèpsics d'Hb, obtinguts a partir de FC no pressuritzada i deshidratats per atomització a 180ºC, eren de color blanc i tenien un contingut en humitat del 4,7 %, un 84,2 % de proteïna i 9,7 % de sals minerals. El procés d'hidròlisi permetia una reducció considerable de la contaminació de la FC, obtenint un producte en pols amb uns recomptes totals de l'ordre de 102-103 ufc·g-1. Pel que fa a la funcionalitat dels hidrolitzats d'Hb deshidratats per atomització, aquests presentaven una elevada solubilitat proteica a pH 5 i 7 i romanien solubles després d'un escalfament a 80ºC durant 30 min. Tanmateix, aquesta hidròlisi afectava molt negativament la capacitat de mantenir escumes estables i l'activitat emulsionant.

Valorization of an Industrial Organosolv-Sugarcane Bagasse Lignin: Characterization and Use as a Matrix in Biobased Composites Reinforced With Sisal Fibers

In the present study, the main focus was the characterization and application of the by-product lignin isolated through an industrial organosolv acid hydrolysis process from sugarcane bagasse, aiming at the production of bioethanol. The sugarcane lignin was characterized and used to prepare phenolic-type resins. The analysis confirmed that the industrial sugarcane lignin is of HGS type, with a high proportion of the less substituted aromatic ring p-hydroxyphenyl units, which favors further reaction with formaldehyde. The lignin-formaldehyde resins were used to produce biobased composites reinforced with different proportions of randomly distributed sisal fibers. The presence of lignin moieties in both the fiber and matrix increases their mutual affinity, as confirmed by SEM images, which showed good adhesion at the biocomposite fiber/matrix interface. This in turn allowed good load transference from the matrix to the fiber, leading to biobased composites with good impact strength (near 500 J m(-1) for a 40 wt% sisal fiber-reinforced composite). The study demonstrates that sugarcane bagasse lignin obtained from a bioethanol plant can be used without excessive purification in the preparation of lignocellulosic fiber-reinforced biobased composites displaying high mechanical properties. Biotechnol. Bioeng. 2010;107: 612-621. (C) 2010 Wiley Periodicals, Inc.

Synthesis and characterization of microcrystalline cellulose produced from bacterial cellulose

In this study, microcrystalline cellulose (MCC) was prepared from the acid hydrolysis of bacterial cellulose (BC) produced in culture medium of static Acetobacter xylinum. The MCC-BC produced an average particle size between 70 and 90 mu m and a degree of polymerization (DP) of 250. The characterization of samples was performed by thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy (SEM). The MCC shows a lower thermal stability than the pristine cellulose, which was expected due to the decrease in the DP during the hydrolysis process. In addition, from X-ray diffractograms, we observed a change in the crystalline structure. The images of SEM for the BC and MCC show clear differences with modifications of BC fiber structure and production of particles with characteristics similar to commercial MCC.

Aproveitamento do resíduo da produção de etanol a partir de farelo de mandioca, como fonte de fibras dietéticas

O presente trabalho teve por objetivo analisar resíduos do farelo de mandioca resultantes de processos de hidrólise enzimática para obtenção de etanol; visando o aproveitamento destes como fonte de fibras dietéticas. Foram realizados quatro ensaios enzimáticos utilizando as enzimas amilolíticas, a-amilase e amiloglucosidase, complementadas ou não com celulase e/ou pectinase. Os resíduos foram caracterizados quanto à composição centesimal, pH, acidez, perfil de açúcares e quanto às fibras (FDA, FDN, celulose, hemicelulose, lignina, açúcares neutros). Realizou-se também a análise microscópica dos resíduos. Pelos resultados obtidos na caracterização dos resíduos calculou-se a energia metabolizável aparente (EM). Observou-se que independente do ensaio enzimático todos os resíduos podem ser usados como fonte de fibras insolúveis. Os resíduos resultantes dos ensaios com pectinase apresentaram uma proporção aproximada de 1:1:1 de amido, fibras e açúcares, sendo a glicose o açúcar majoritário, e com energia metabolizável aparente de cerca de 2,6 kcal/g. Já os resíduos, onde não se utilizou a pectinase a proporção foi de 2:1:1 aproximadamente e a energia 3,1 kcal/g. A análise microscópica dos resíduos mostrou a presença de amido não hidrolisado preso às células em todos os ensaios enzimáticos sendo que, nos resíduos dos ensaios com pectinase a quantidade observada foi bem inferior aos demais. Uma possível alternativa para diminuir o valor calórico dos resíduos seria a lavagem com água após a prensagem para extração do hidrolisado para fermentação.

Yttrium iron garnet heterocoagulated by silica

Coated purpose of homogeneous distribution as a second phase is introduced in magnetic systems. Yttrium iron garnet (YIG) shows special interest as magnetic dye, microwave absorber, and magnetic fluids when heterocoagulated by other material. Surface and interface magnetic properties are intimately connected with the new properties of the silica on YIG system. Néel first introduced the concept of surface anisotropy, and Chen et al. developed a model that describes the anisotropy effects at the boundary surface particle, which was applied in this work. Spherical YIG particles were prepared by coprecipitation method and coated with silica using the tetraethylorthosilicate (TEOS) hydrolysis process. The silica-YIG boundary was investigated by transmission electron microscopy. Hysteresis loops comparatively show the profile of the naked and silica-covered YIG particles. The surface anisotropies were calculated using the Chen et al. approach. Indeed, in heterocoagulation systems, the surface anisotropy is a result of the interface symmetry breaking, as observed.