13‐Hydroxy‐9Z,11E‐Octadecadienoic Acid Production by Recombinant Cells Expressing Burkholderia thailandensis 13‐Lipoxygenase

Linoleate 13‐lipoxygenase from Burkholderia thailandensis was expressed in Escherichia coli for the production of 13‐hydroxyoctadecadienoic acid (13‐HODE), an antiseptic emulsifier. Linoleate 13‐lipoxygenase in cells had higher thermal stability than the purified enzyme. To increase 13‐HODE production, recombinant cells were permeabilized by solvents, detergents, salts, and other chemicals. The enzymatic activity in cells was the highest for permeabilized cells treated with 0.5 M NaCl among the permeabilizers tested. The optimal reaction conditions for the production of 13‐HODE from linoleic acid by permeabilized cells treated with 0.5 M NaCl were at pH 7.5, 25 °C, 20 g/l linoleic acid, 15 g/l cells, 0.15 mM Cu²⁺, and 6 % (v/v) methanol in a 100‐ml baffled flask containing a 5‐ml working volume with agitation at 200 rpm. Under these conditions, permeabilized cells produced 15.8 g/l 13‐HODE after 30 min with a conversion yield of 79 % (w/w) and a productivity of 31.6 g/l/h. The conversion yield and productivity of permeabilized cells for 13‐HODE production were higher than those of purified and crude enzymes as well as nonpermeabilized cells. Therefore, permeabilized cells were efficient biocatalysts for 13‐HODE production. To the best of our knowledge, this is the first report of the production of 13‐HODE using cells.     

Evaluation of the effects of operational parameters in the pretreatment of sugarcane bagasse with diluted sulfuric acid using analysis of variance

The pretreatment of lignocellulosic residues has been extensively studied as a method to disrupt the cellulose–hemicelluloses–lignin complex in biomass to access the sugars in their respective components. In this work, we carried out a study using sulfuric acid pretreatment of sugarcane bagasse by varying the following operational parameters: solid loading (10–30% of bagasse relative to the volume of the sulfuric acid solution), sulfuric acid concentration (0.5–2.5% relative to the dry mass of bagasse), reaction time (5–25?min), and temperature (135–195°C). The obtained solids from each pretreatment condition were submitted to enzymatic hydrolysis under the same process conditions: 0.232?g of Celluclast 1.5?L and 0.052?g of Novozym 188 per g of pretreated sugarcane bagasse, 72?h of hydrolysis, and 200?rpm of agitation at 50°C. Using central composite rotational design configuration in the experiments and analysis of variance, the results indicate that the conditions that produced larger quantities of glucose by enzymatic hydrolysis (0.35?g glucose/g pulp) with minimum amounts of degradation products were as follows: 20% solids loading, 15?min of reaction time, 1.5% sulfuric acid, and a minimum temperature of reaction of 170°C.     

Chemo‐enzymatic epoxidation of linoleic acid: Parameters influencing the reaction

The effect of reaction parameters on lipase‐mediated chemo‐enzymatic epoxidation of linoleic acid was investigated. Hydrogen peroxide was found to have the most significant effect on the reaction rate and degree of epoxidation. Excess of hydrogen peroxide with respect to the amount of double bonds was necessary in order to yield total conversion within a short time period, as well as at temperatures above 50 °C to compensate for hydrogen peroxide decomposition. However, prolonged incubation with high excess of hydrogen peroxide leads to the accumulation of peracids in the final product. The reaction rate increased also with increasing hydrogen peroxide concentration (between 10 and 50 wt‐%); however, at the expense of enzyme inactivation. Linoleic acid was completely epoxidized when used at a concentration of 0.5–2 M in toluene at 30 °C, while in a solvent‐free medium, the reaction was not complete due to the formation of a solid or a highly viscous oily phase, creating mass transfer limitations. Increasing the temperature up to 60 °C also improved the rate of epoxide formation.     

Dilute acid depolymerization of cellulose in aqueous phase: Experimental evidence of the significant presence of soluble oligomeric intermediates

The objective of this investigation is to show that rapid hydrolysis can be achieved by passage of aqueous cellulosic suspensions (2–10% solids) through capillaries followed by sudden decompression and post-treatment under dilutes acid conditions. Through detailed experimentation within the 200–240°C temperature range and at low sulfuric acid concentrations (0.2–1.0% w/w) it was found that liquefaction of the cellulose proceeds via extensive formation of soluble oligomeric intermediates. A simple kinetic model has been developed to explain the liquefaction-saccharification patterns of the cellulose. The sequence considered is: Cellulose → Oligo-derivatives → Glucose → Decomposition products Quantitative values of the rate constants have been determined and a discussion on the selectivity of the overall reaction sequence is presented.     

Stabilization of Ethyl‐Cellulose Oleogel Network Using Lauric Acid

The use of oleogels in a wide range of applications requires a broad diversity of gel properties tailored for each purpose. The current research explores the combination of ethyl‐cellulose (EC) with lauric acid (LA), at different ratios with an emphasis to explore each component contribution and function in the gel structure and properties. The results suggest that oleogel physical properties strongly depend on the EC concentration. A transition from antagonistic to synergistic behavior between EC and LA with respect to the mechanical properties is observed above 4 wt% polymer. This behavior is seen in all LA concentrations, suggesting that the main effect arises from the EC while the LA acts as a stabilizer. In addition, LA reduces EC gelation temperature from approximately 140 °C to 79–101 °C, depending on the EC concentration, suggesting a ‘plasticizing’ effect. The recovery ability of EC oleogel after large amplitude deformation is improved from 16% to 34% due to the LA crystalline nature. LA crystal structure is not affected by EC concentration; however its crystallization temperature shifts to a lower temperature. Practical Applications: These results provide a broad overview of the composition‐function relation obtained while combining EC with LA.     

Graft copolymerization of acrylic acid onto cellulose: Effects of pretreatments and crosslinking agent

The graft copolymerization of acrylic acid (AA) and 2‐acrylamido 2‐methylpropane sulfonic acid (AASO₃H) onto cellulose, in the presence or absence of crosslinking agent N,N′‐methylene bisacrylamide (NMBA), by using different concentrations of ceric ammonium nitrate (CAN) initiator in aqueous nitric acid solution at either 5 or 30°C was investigated. To investigate the effect of pretreatment of cellulose on the copolymerization, before some grafting reactions cellulose was pretreated with either 2 or 20 wt % NaOH solutions or heated in distilled water/aqueous nitric acid (2.5 × 10^?3 M) at 55°C. To determine how the excess of initiator affects the grafting and homopolymerization, separate reactions were carried out by removing the excess of ceric ions by filtration of the mixture of initiator solution and cellulose before the monomer addition. Extraction‐purified products were characterized by grafting percentage and equilibrium swelling capacity. Pretreatment of cellulose with NaOH solutions decreased the grafting percentage of copolymers. In the case of AA–AASO₃H mixtures, nonpretreated cellulose gave a higher grafting percentage than NaOH‐pretreated cellulose. Filtration also lowered the grafting of AA on the cellulose in the cases of pretreatment with either water or nitric acid. Copolymers with the highest grafting percentage (64.8%) and equilibrium swelling value (105 g H₂O/g copolymer) were obtained in grafting reactions carried out in the presence of NMBA at 5°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2267–2272, 2001     

Hydrothermal conversion of carbohydrate biomass to lactic acid

We investigated the hydrothermal conversion of the carbohydrates including glucose, cellulose, and starch to lactic acid using NaOH and Ca(OH)₂ as alkaline catalysts. Both catalysts significantly promoted the lactic acid formation. The highest yield of lactic acid from glucose was 27% with 2.5 M NaOH and 20% with 0.32 M Ca(OH)₂ at 300°C for 60 s. The lactic acid yields from cellulose and starch were comparable with the yield from glucose with 0.32 M Ca(OH)₂ at 300°C, but the reaction time in the case of cellulose was 90 s. The mechanism of lactic acid formation from glucose was discussed by identifying the intermediate products. Lactic acid may be formed via the formation of aldoses of two to four carbons including aldose of three carbons, which are all formed by reverse aldol condensation and double bond rule of hexose. This implies that carbon–carbon cleavage occurs at not only C₃? C₄ but also at C₂? C₃. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Kinetics of high temperature conversion of furfuryl alcohol in water

The kinetics of furfuryl alcohol conversion to 4-hydroxycyclopent-2-enone (4-HCP), polymers and levulinic acid (LA) in water was investigated in batch reactors at temperatures 110–200 °C. These acid catalyzed reactions are at high temperatures catalyzed by hydrogen ions formed by autodissociation of water. At temperatures 180–200 °C and reaction times 5–10 min more than 50 mol% yields of 4-HCP were achieved. A kinetic model which describes experimental data was developed. The values of the apparent activation energies of the main reaction and the side reactions are very similar, what means that the selectivity of 4-HCP formation is independent on the temperature. It indicates, that is attractive to perform furfuryl alcohol transformation to 4-HCP at high temperatures without changing the selectivity.     

Continuous Gradient Temperature Raman Spectroscopy of Oleic and Linoleic Acids from −100 to 50 °C

We analyzed the unsaturated fatty acids oleic (OA, 18:1n‐9) and linoleic (LA, 18:2n‐3), and a 3:1 LA:OA mixture from ?100 to 50 °C with continuous gradient temperature Raman spectroscopy (GTRS). The 20 Mb three‐dimensional data arrays with 0.2 °C increments and first/second derivatives allowed rapid, complete assignment of solid, liquid, and transition state vibrational modes. For OA, large spectral and line width changes occurred in the solid state γ to α transition near ?4 °C, and the melt (13 °C) over a range of only 1 °C. For LA, major intensity reductions from 200 to 1750 cm^?1 and some peak shifts marked one solid state phase transition at ?50 °C. A second solid state transition (?33 °C) had minor spectral changes. Large spectral and line width changes occurred at the melt transition (?7 °C) over a narrow temperature range. For both molecules, melting initiates at the diene structure, then progresses towards the ends. In the 3:1 LA:OA mixture, some less intense and lower frequencies present in the individual lipids are weaker or absent. For example, modes assignable to C8 rocking, C9H–C10H wagging, C10H–C11H wagging, and CH3 rocking are present in OA but absent in LA:OA. Our data quantify the concept of lipid premelting and identify the flexible structures within OA and LA, which have characteristic vibrational modes beginning at cryogenic temperatures.     

Characteristics of cellulose isolated by a totally chlorine‐free method from Caragana korshinskii

The chemical composition and fiber morphology of Caragana korshinskii were investigated in this study. Isolation of cellulose was performed in a nonsulfur acetic acid/nitric acid system under various conditions. The influence of three factors, i.e., nitric acid concentration (0, 2, 4, 6, 8, or 10%), temperature (95, 100, 110, 115, 120, or 130°C), and reaction time (30, 40, 50, 60, or 90 min) on the cellulose properties (viscosity, yield, and molecular weight) was studied. The cellulose isolated was characterized by using Fourier transform infrared, gas chromatography, high performance liquid chromatography, solid‐state cross‐polarization magic angle spinning carbon‐13 nuclear magnetic resonance, wide‐angle X‐ray diffraction, and thermogravimetric analysis/differential scanning calorimetry techniques. The results showed that the treatment using 80% acetic acid and nitric acid as a catalyst under the given conditions resulted in slight acetylation of the cellulose and increased the degree of crystallinity of cellulose except for significant degradation of lignin and hemicellulosic polymers. The thermal stability of the cellulose declined with an increase in nitric acid concentration. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3251–3263, 2006     

Grafting biodegradable polyesters onto cellulose

To increase the compatibility between cellulose fibers and polyester matrix an original method for grafting hydrophobic oligoesters onto cellulose was proposed. Two kinds of cellulose substrates were employed as cellulose films and microcrystalline cellulose powder. Different oligoesters containing reactive end groups based on poly(DL ‐lactic acid) PDL‐LA, poly(ε‐caprolactone) PCL and poly(3‐hydroxyalkanoate)s PHA were first prepared and characterized by size exclusion chromatography (SEC), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC). The carboxylic end groups of the polyesters were activated using thionyl chloride (SOCl₂) to increase the esterification reaction with the hydroxyl groups of the cellulose. The esterification was realized in a heterogenous medium without any catalyst by deposition of chloride oligoesters in solution (2–100 g L⁻¹) onto cellulose film at different temperatures (25–105°C) during 1–12 h. The successful grafting on the various substrates was confirmed on the basis of FTIR spectroscopy, contact angle measurement, X‐ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). In particular, it is shown that a small quantity of grafted oligoesters led to a significant increase of the hydrophobic character of the cellulose with a contact angle near 130°. The increase of hydrophobicity of cellulose is independent of the nature and length of grafting oligoesters. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of cellulose triacetate-I from microfibrillated date seeds cellulose (<Emphasis Type="Italic">Phoenix dactylifera L.</Emphasis>)

Cellulose triacetate (CTA) has successfully been synthesized from microfibrillated date seeds cellulose. The cellulosic material under study constituted 84.9% amorphous phase with a degree of polymerization of 950. Acetylation was conducted at 50 °C under optimized heterogeneous conditions by acetic anhydride as acetyl donor, acetic acid as solvent and sulfuric acid as catalyst. In this process, cellulose was acetylated without dissolving the material throughout. The acetylated cellulose chains on the surface were dissolved gradually in acetic acid, which created new accessible zones. The yield of cellulose triacetate was studied varying acetic acid, acetic anhydride and catalyst concentrations, as well as reaction times. The ratio between the intensity of the acetyl C=O stretching band at around 1740 cm^?1 and the intensity of C–O stretching vibration of the cellulose backbone at 1020–1040 cm^?1 was used to optimize the reaction time. The optimal reaction conditions of 8% concentration of sulfuric acid, acetic anhydride/cellulose weight ratio of 3:1, acetic acid/cellulose weight ratio of 7:1, reaction time of 3 h and reaction temperature of 50 °C have given highest yield of cellulose triacetate, of about 79%. The obtained date seeds-based cellulose triacetate was characterized thoroughly by Fourier transform infrared (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance spectroscopy (NMR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The synthesized product was identified as cellulose triacetate-I (CTA-I) characterized by a melting temperature of 217 °C and a decomposition temperature of 372 °C. These results demonstrated that date seeds can be used as potential source of microfibrillated cellulose which can be easily functionalized.     

Bioconversion of linoleic acid to conjugated linoleic acid by Lactobacillus reuteri under different growth conditions

BACKGROUND: Lactobacillus reuteri was grown in De Man/Rogosa/Sharpe (MRS) broth (initial pH 6.5) supplemented with free linoleic acid (LA) at different concentrations (5, 10, 20 and 30 mg mL^?1) and incubated aerobically at different temperatures (4, 10, 16, 22 and 30 °C) in order to test its ability to accomplish the bioconversion of LA to conjugated linoleic acid (CLA). Temperatures and LA concentrations producing the highest conversion of LA to CLA in the initial trials were tested further using micro‐anaerobic conditions and a lower initial pH (5.5). RESULTS: Data showed that production of CLA exhibited variations with regard to the fermentation conditions used. The highest production of CLA (0.108 mg mL^?1) was measured in a broth containing 20 mg mL^?1 free LA that was incubated aerobically at 10 °C for 30 h. When the initial pH of the reaction medium was reduced from 6.5 to 5.5, CLA production decreased. Micro‐aerobic conditions reduced the ability of Lb. reuteri to produce CLA, since production of CLA under aerobic conditions was at least 1.4 times greater. CONCLUSION: Production of CLA by Lb. reuteri at low temperatures and relatively high substrate concentrations provides novel opportunities for the development of functional foods with the benefits of enrichment in CLA and probiotic bacteria. Copyright © 2008 Society of Chemical Industry     

Influence of C18 long chain fatty acids on butyrate degradation by a mixed culture

Butyrate degradation in the presence of C₁₈ long chain fatty acids (LCFAs) was examined under anaerobic conditions at 21 °C. Butyrate degradation rates were a function of linoleic acid (LA) and oleic acid (OA) concentration but independent of the amount of stearic acid (SA) added. Within 2–4 h, butyrate reached undetectable levels in the control cultures. However, in cultures fed with LA, butyrate was removed within between 12 and 25 h and within 2–12 h for cultures inoculated with OA or SA. Propionate was detected in cultures fed with 50 mg dm^?3 LA and in cultures inoculated with OA and SA. LA exerted a greater inhibitory effect on butyrate‐degrading organisms than OA and SA with longer removal times observed in cultures fed with LA. The propionate and acetate removal times and quantity produced were not related to the type and concentration of LCFA. Copyright © 2004 Society of Chemical Industry     

Synthesis of polyglactin by melt/solid polycondensation of glycolic/L‐lactic acids

Polyglactin was successfully synthesized by the melt/solid polycondensation of a mixture of glycolic acid (GA) and L ‐lactic acid (LA) mostly at a GA to LA monomer ratio of 90/10. In the polymerization procedure, a solid polycondensate was first prepared by melt‐polycondensation at 150–190 °C, mechanically crushed into particles of various sizes (150–180, 180–210, 210–250, 250–300 and 300–355 µm), and subjected to solid‐state post‐polycondensation at 170 °C for 10–20 h. The polyglactin finally obtained was a colourless solid. Catalyst screening revealed that the single use of methanesulfonic acid gave the highest molecular weight of the product. Starting from the crushed melt‐polycondensate with a diameter range of 180–250 µm, the highest number‐average molecular weight of attained was 80 000 Da. This process can afford a facile route to large‐scale synthesis of polyglactin with high molecular weight. Copyright © 2004 Society of Chemical Industry     

Low-Temperature Dilute Acid Hydrolysis of Oil Palm Frond

Oil palm frond (OPF) fiber, a lignocellulosic waste from the palm oil industry, contains high cellulose and hemicellulose content, thus it is a potential feedstock for simple sugars production. This paper describes the two-stage hydrolysis process focusing on the use of low-temperature dilute acid hydrolysis to convert the hemicellulose in OPF fiber to simple sugars (xylose, arabinose, and glucose). The objective of the present study was to evaluate the effect of operating conditions of dilute sulfuric acid hydrolysis undertaken in a 1 L self-built batch reactor on xylose production from OPF fiber. The reaction conditions were temperatures (100–140°C), acid concentrations (2–6%), and reaction times (30–240 min). The mass ratio of solid/liquid was kept at 1:30. Analysis of the three main sugars glucose, xylose, and arabinose were determined using high-pressure liquid chromatography. The optimum reaction temperature, reaction time, and acid concentration were found to be 120°C, 120 min, and 2% acid, respectively. Based on the potential amount of xylose (10.8 mg/mL), 94% conversion (10.15 mg/mL) was obtained under the optimum conditions with small amount of furfural (0.016 mg/mL). To enhance the effectiveness of dilute acid hydrolysis, the hydrolysis of OPF fiber was also performed using ultrasonic-pretreated OPF fiber. The effects of ultrasonic parameters power (40–80%) and ultrasonication times (20–60 min) were determined on sugar yields under optimum hydrolysis conditions (2% acid sulfuric, 120°C and 120 min). However, the use of ultrasonication was found to have detrimental effect on the yield of simple sugars due to the 10-fold increase in the formation of furfural.     

Evaluation of chlorogenic acid and its metabolites as potential antioxidants for fish oils

The antioxidant effects on cod liver oil (CLO) of chlorogenic acid (CGA) and its metabolites, caffeic acid (CA) and quinic acid (QA), were investigated. All three chemicals were separately added to CLO at a concentration range of 0.001–0.080 wt‐% and tested by Rancimat. CA was the best antioxidant; its antioxidant effect was directly proportional to the dose added, but only within the concentration range of 0.005–0.050 wt‐%. QA did not show any effect on CLO oxidation, while CGA revealed itself as a weak antioxidant. Cytotoxicity was also evaluated by using murine 3T6 fibroblasts treated for 24 h with CGA, CA and QA at a concentration range of 0.1–5.0 mM. QA did not have an influence on cell proliferation, while CGA and CA showed a significant anti‐proliferative activity already at a concentration of 0.1 mM. Finally, compounds similar to the standard 8‐iso prostaglandin F_2α, called CLO‐“isoprostanes”‐like compounds, were isolated. At high temperature (100 and 110 °C) CLO‐“isoprostanes‐like” compounds did not show a relevant pro‐oxidant action on the refined olive oil to which they were added in variable amounts. On the contrary, the CLO‐“isoprostanes”‐like compounds significantly decreased the antioxidant effectiveness of CA. Indeed, at a CLO‐“isoprostanes‐like” compound dose of 300 µg, the antioxidant effectiveness of CA was halved.     

Determination of the Optimum Conditions for Leaching of Malachite Ore in H2SO4 Solutions

The Taguchi method has been used to determine the optimum conditions for the dissolution of malachite ore in H₂SO₄ solutions. The chosen experimental parameters and their range were (i) reaction temperature: 15 to 45 °C, (ii) solid‐to‐liquid ratio: 1/10 to 1/3 g cm^–3, (iii) acid concentration (in weight): 2 % to 10 %, (iv) particle size: –40 to –3.5 mesh, (v) stirring speed: 240 to 720 rpm, and (vi) reaction time: 5 to 45 minutes. The optimum conditions were found to be reaction temperature: 40 °C, solid‐to‐liquid ratio: 1/3 g cm^–3, acid concentration (in weight): 10 %, particle size: –30 mesh, stirring speed: 480 rpm, and reaction time: 45 minutes. Under these optimum working conditions, the dissolution of copper and iron in malachite ore was 100 % and 58 %, respectively. Besides, alternative working conditions reducing the total cost and dissolution of iron were found.     

Graft copolymerization of acrylic acid on cellulose: Reaction kinetics of copolymerization

Acrylic acid (AA) was grafted to cellulose by using ceric ammonium nitrate (CAN) initiator in aqueous nitric acid solution at 30, 50, 70, and 90°C during reaction periods of 30 to 180 minutes. About 45% of the AA was polymerized at 90°C after 180 minutes. The grafted polymer and homopolymer were isolated by acetone from the reaction mixture, dried, and subjected to Soxhlet extraction with dioxane to separate the homopolymer, poly(acrylic acid), from the graft copolymer. The water absorption capacities and grafting values of grafted cellulose were also determined. The maximum grafting yield was obtained at 30°C. It was also observed that polyacrylic acid-grafted cellulose produced at 30°C had the highest water retention capacity. The time dependence of AA conversion allowed calculation of first-order reaction rate constants. These rate constants were then used to determine apparent activation energies. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 929–934, 1997     

Comparative study of cellulose isolated by totally chlorine‐free method from wood and cereal straw

Highly purified cellulose preparations were obtained by pretreatment of dewaxed barley straw, oil palm frond fiber, poplar wood, maize stems, wheat straw, rice straw, and rye straw with 2.0% H₂O₂ at 45°C and pH 11.6 for 16 h, and sequential purification with 80% acetic acid–70% nitric acid (10/1, v/v) at 120°C for 15 min. The purified cellulose obtained was relatively free of bound hemicelluloses (2.3–3.2%) and lignin (0.4–0.6%) and had a yield of 35.5% from barley straw, 39.6% from oil palm frond fiber, 40.8% from poplar wood, 36.0% from maize stems, 34.1% from wheat straw, 23.4% from rice straw, and 35.8% from rye straw. The weight‐average molecular weights of the purified cellulose ranged from 39,030 to 48,380 g/mol. The thermal stability of the purified cellulose was higher than that of the corresponding crude cellulose. In comparison, the isolated crude and purified cellulose samples were also studied by Fourier transform IR and cross‐polarization/magic‐angle spinning ¹³C‐NMR spectroscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 322–335, 2005