Biodiesel Fuel Production by Enzymatic Transesterification of Oils: Recent Trends, Challenges and Future Perspectives

Liquid fuels have been used for many years as the most dominant and basic fuel for motor engines. However, declining fossil fuel resources as well as the tendency for developing new renewable biofuels have shifted the interest of the society towards finding novel alternative fuel sources. Biodiesel (monoalkyl esters of long-chain fatty acids) has a great potential as an alternative diesel fuel. From an environmental point of view it shows clear advantages over conventional fuel: it comes from renewable sources, and hence does not contribute to new carbon dioxide emission, it is biodegradable, its combustion products have reduced levels of particulates, sulphur oxides, carbon oxides, nitrogen oxides, and therefore, significantly reduces pollution (Al-Zuhair, 2007; Salis et al., 2005). One of the advantages of biodiesel in comparison to other biofuels is that biodiesel can be pumped, stored and handled using the same infrastructure employed for conventional diesel fuel (Robles-Medina et al., 2009). Also, major advantage of biodiesel as an alternative fuel is that its energy content is similar to conventional fuels, so it can be used either on its own or mixed with conventional diesel fuel, with no need of altering existing engines (Bozbas, 2005). European countries have recognized need for alternative fuels and issued the Directive on the Promotion of the use of biofuels and other renewable fuels for transport (2003/30/EC). The Directive stipulates that EU countries should replace 5.75% of fossil fuels with alternative, biofuels until 31. December 2010. This Directive has been amended by Directive 2009/28/EC which also promotes the usage of energy from renewable sources (aims at achieving a 20% share of energy from renewable sources in the EU’s final consumption of energy by 2020). In 2005, the estimated world production of biodiesel was 2.92 million tones of which 87% was obtained in EU. More importantly, between 2000 and 2005 world production increased threefold, indicating that share of biodiesel in global fuel production will significantly increase in future (Mousdale, 2008). ..

Utilization of soy hull for production of pectic fiber

Soy hull, a by-product of soybean processing, was investigated as a source of pectic fiber. Pectic fiber was obtained with yield of 5.72 g/100 gDW. Soy hull pectic fiber demonstrated good solubility (83.49%) and high molecular weight with Mw of dominant fraction 3192.6 kDa. These favorable characteristics could indicate a great potential for application in food industry

Recovery and functional properties of rubisco protein from conventional and enzymatic extractions

Protein isolates extracted by conventional and enzymatic protocols from pumpkin leaves were evaluated. Pumpkin leaves represent waste material that can be used for extraction of RuBisCO protein. Results showed that usage of Viscozyme for enzyme-assisted extraction enhanced recovery of protein by 30% compared to conventional extraction protocol. Moreover, protein extracted by enzymatic treatment showed improved solubility and oil holding capacity by 71% and 13%, respectively. Our findings might indicate a possibility of usage of enzyme treatment that would enable production of protein isolate with properties and/or in quantities tailored to their particular application in food systems

Polypyrrole-based Enzyme Electrode with Immobilized Glucose Oxidase for Electrochemical Determination of Glucose

Polypyrrole enzyme electrode was formed by immobilization of glucose oxidase via glutaraldehyde into electrochemically synthesized polypyrrole on glassy carbon electrode. Electrochemical synthesis was performed in 0.5 mol dm(-3) HCl and 0.2 mol dm(-3) pyrrole at constant current density of 2 mA cm(-2). Chronopotentiometric curves of polypyrrole enzyme electrode were recorded at current density of 42 nA cm(-2) for different glucose concentrations. The determined value of the apparent Michaelis-Menten constant was 0.045 mmol dm(-3) which is significantly lower than that of free enzyme indicating enhanced enzyme efficiency when it is immobilized into electroconducting polymer matrix

Immobilization of Horseradish Peroxidase on Magnetite-Alginate Beads to Enable Effective Strong Binding and Enzyme Recycling during Anthraquinone Dyes’ Degradation

The aim of this study was to investigate covalent immobilization of horseradish peroxidase (HRP) on magnetic nanoparticles (Mag) encapsulated in calcium alginate beads (MABs) for color degradation, combining easy and fast removal of biocatalyst from the reaction mixture due to its magnetic properties and strong binding due to surface alginate functional groups. MABs obtained by extrusion techniques were analyzed by optical microscopy, FEG-SEM and characterized regarding mechanical properties, magnetization and HRP binding. HRP with initial concentration of 10 mg/gcarrier was successfully covalently bonded on MABs (diameter ~1 mm, magnetite/alginate ratio 1:4), with protein loading of 8.9 mg/gcarrier, immobilization yield 96.9% and activity 32.8 U/g. Immobilized HRP on MABs (HRP-MABs) was then used to catalyze degradation of two anthraquinonic dyes, Acid Blue 225 (AB225) and Acid Violet 109 (AV109), as models for wastewater pollutants. HRP-MABs decolorized 77.3% and 76.1% of AV109 and AB225, respectively after 15 min under optimal conditions (0.097 mM H2O2, 200 mg of HRP-MABs (8.9 mg/gcarrier), 0.08 and 0.1 g/mg beads/dye ratio for AV109 and AB225, respectively). Biocatalyst was used for 7 repeated cycles retaining 75% and 51% of initial activity for AB225 and AV109, respectively, showing potential for use in large scale applications for colored wastewater treatment

Polypyrolle/glucose oxidase electrode for electrochemical determination of glucose

A growing interest in biosensors for use in medical, environmental and food analysis\ud has been recognized. Biosensors are devices that transform chemical information, usually the concentration of a specific sample component, into an analytically useful signal. Their selectivity depends on the characteristics of enzyme and biosensors’ response rate and sensitivity on electroconducting polymer used. Glucose oxidase (GOx) is the most widely used enzyme in the field of biosensors because of its high specificity for a commercially important analyte, high turnover number and high stability. On the other side, among the conducting polyheterocyclic polymers, polypyrolle (PPy) is of particular interest because the relatively low oxidation potential of the monomer enables films to be grown from aqueous solutions that are compatible with most of biological elements. The aim of this study was to investigate the possibility of glucose determination using enzyme electrode obtained by immobilization of GOx into polypyrolle electrochemically polymerised on platinum electrode. Electrochemical synthesis was performed in 0.5 mol dm-3 HCl and 0.2 mol dm-3 pyrolle at constant current density of 2 mA cm-2. Polypyrolle/enzyme electrode was formed by immobilization of glucose oxidase via glutaraldehyde into electrochemically synthesized polypyrolle on platinum electrode. Apparent Michaelis constant was determined and it was found to be 0.045 mmol dm-3, which is much lower than that of free enzyme indicating enhanced enzyme efficiency when it is immobilized into polymer electroconducting matrix. PPy/enzyme electrode lost 5% and 18% of its initial signal after 5 and 20 days, respectively

Design of a polyaniline based biosensor electrode for glucose: A comparative study of two immobilized systems

The present study compares the results of two different methods employed for preparation of polyaniline based glucose biosensor with respect to enzyme loading, biosensing efficiency and potential stability. Kinetic analysis of the potentiometric data for two enzyme immobilized electrode systems show that the GOx/PANI electrode is suitable for assaying samples with low analyte concentrations, whereas the GOx/m-ABA/PANI electrode system exhibits a better potential stability. It may therefore be possible to achieve high level of biosensing efficiency by chemical modeling and synthesis combined with careful selection of the immobilization method

Enzymatic synthesis of vitamin B6 precursor

3-Cyano-4-ethoxymethyl-6-methyl-2-pyridone is an important precursor in the synthesis of vitamin B6, obtained in the addition reaction between 2-cyanoacetamide and 1-ethoxy-2,4-pentanedione catalyzed by lipase from Candida rugosa (triacylglycerol ester hydrolases, EC 3.1.1.3). This work shows new experimental data and mathematical modeling of lipase catalyzed synthesis of 3-cyano-4-ethoxymethyl-6-methyl-2-pyridone, starting from 1-ethoxy-2,4-pentanedione and 2-cyanoacetamide. Kinetic measurements were done at 50 oC with enzyme concentration of 1.2 % w/v. Experimental results were fitted with two kinetic models: the ordered bi-ter and ping-pong bi-ter model, and the initial rates of the reaction were found to correlate best with a ping-pong bi-ter mechanism with inhibition by 2-cyanoacetamide. Obtained specificity constants indicated that lipase from C. rugosa had higher affinity towards 1-ethoxy-2,4-pentanedione and less bulky substrates. [Projekat Ministarstva nauke Republike Srbije, br. 172013, br. III 46010 and br. 172049

Immobilization of α-amylase from bacillus paralicheniformis on bentonites

α-Amylase from Bacillus paralicheniformis (BliAmy) is a highly efficient raw starch digesting enzyme. Starch is an inexpensive source of many food industrial products. Naturally occurring clay are non-toxic, environmentally friendly and inexpensive. Therefore, immobilization of BliAmy by adsorption on three differently modified bentonites was studied. Modifications included common Na-exchange procedure, acid activation, and alkali activation. The modified clays were characterized by X-ray powder diffraction, mercury intrusion porosimetry and the points of zero charge were determined. The adsorption of the enzyme was significantly influenced by the type of modification of bentonite, being the highest for the acid-activated bentonite with the highest porosity. On the other hand, the highest enzyme activity for immobilized α-amylase was obtained with alkali-modified bentonite (98 U/g), suggesting it as a good candidate for immobilization of α-amylase for application in the food industry

Stable, environmentally friendly and inexpensive biocatalysts for obtaining important ingredients applicable in the food industry

Clays are naturally occurring, environmentally friendly, chemically inert, thermostable, inexpensive resources that are easily modified into materials with tailored properties. As such, they can be used as suitable supports for enzyme immobilization and application in the food industry. Natural polysaccharides starch, xylan, pullulan, and its derivatives obtained by the action of enzymes, have numerous potentials for food industrial applications. In this work the enzyme supports were prepared from bentonite from Coal mine "Bogovina", Serbia by acid activation (AA), pillaring (P), and pillaring followed by acid activation (PAA). The characterization of the obtained materials included chemical and phase composition, surface acidity, and textural properties. After characterization, -amylase from Bacillus paralicheniformis (BliAmy), commercial xylanase from Sigma-Aldrich (Xyl), and pullulanase from B. paralicheniformis (BliPull) were immobilized on bentonite based supports by 24 h adsorption at 25 °C. The obtained biocatalysts BliAmy-AA (106 IU/g), Xyl-P (74 IU/g), and BliPull-PAA (45 IU/g) showed very good storage stability with the activity preserved after 4 weeks of testing. Products of hydrolysis were detected by TLC and indicate a promising application in the food industry