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The use of spherical millimetric gamma-alumina (γ-Al2O3) as a catalyst support for the production of biodiesel from palm oil was demonstrated. The catalyst support was produced using dripping method, and KI catalyst was loaded on the support using impregnation method. The highest FAME (fatty acid methyl ester) yield of 98% was obtained when the reaction was carried out under the conditions of catalyst to oil ratio of 0.6 g (4wt.%, gcat./goil) using View the MathML source of catalyst loading, reaction time of 4 h, temperature of 60 °C and methanol to palm oil molar ratio of 14:1. XRD (X-ray diffraction) analysis showed the formation of K2O and KAlO2 phases on the KI/γ-Al2O3 catalyst which were possibly the active sites for the transesterification reaction. The highest number and strength of basic sites generated from the solid phase reaction of the KI/γ-Al2O3 catalyst loaded with 0.24 g kF/g γ-Al2O3 were confirmed by temperature programmed desorption of CO2 (CO2-TPD) analysis. The nitrogen adsorption–desorption isotherms was revealed a mesoporous structure of the catalysts. The leaching of potassium species in reused catalysts was observed, as verified by XRF (X-ray fluorescence). KI/γ-Al2O3 had a long life time and maintained sustained activity even after being repeatedly used for 11 cycles. The biodiesel yield was comparable to that produced from smaller catalysts. Thus, the catalyst could be potential for industrial use, as they can be handled safely, easily separated from the process fluid and used in fixed bed reactor to minimize pressure drop.

Lactic acid bacteria (LAB) have been used for food fermented products since ancient time, which not limited to dairy products. Some Asian traditional food is produced through LAB fermentation. LAB consist of the Gram-positive genera including lactobacillus, which produce lactic acid as the end product of a carbohydrate fermentation. Lactobacillus is one of the important LAB that have been widely applied in food fermentation because of their fermentative ability to enhance food safety, nutrition and to improve health related benefits (as probiotics bacteria). Lactobacillus also received much attention for lactic acid production. This is because lactic acid is highly demanded for the production of poly-l-lactate biodegradable plastics in recent days. The viability and microbial growth of Lactobacilli have been known to be inhibited by its end product (i.e. lactic acid). One of the common solutions to overcome the inhibition issue is by using encapsulation technology. Encapsulation offers several advantages for lactobacilli fermentation which included protection to the bacterial from harsh environments (e.g. pH, temperature, shear stress), retaining cells in continuous process, and allowing reuse of the bacteria. Encapsulation can be achieved in two forms; beads or capsules. Apart from beads, the capsules consisted of a defined inner core which surrounded by a semi permeable membrane. The content of the inner core could be in the form of liquid or solid. Liquid core capsules provide plenty of space for microbial growth (in inner core), eliminate cell release to fermentation medium and minimize mass transfer resistance of solutes. The main focus of this review was on the liquid core capsules produced by Ca-alginate bio-gel. In general, Ca-alginate liquid core capsules can be produced using single step methods or multiple steps methods. The details of the method used to produce the liquid core capsules were described and discussed. The use of the capsules for lactobacill

The aim of this study was to investigate the inter-relationship between process variables and the size and shape of pectin solution droplets upon detachment from a dripping tip as well as Ca-pectinate beads formed after gelation via image analysis. The sphericity factor (SF) of the droplets was generally smaller than 0.05. There was no specific trend between the SF of the droplets and the pectin concentration or the dripping tip radius. The SF the beads formed from high-concentration pectin solutions and a small dripping tip was smaller than 0.05. The results show that the Reynolds number and Ohnesorge number of the droplets fall within the operating region for forming spherical beads in the shape diagram, with the exception to the lower boundary. The lower boundary of the operating region has to be revised to Oh = 2.3. This is because the critical viscosity for Ca-pectinate bead formation is higher than that of Ca-alginate beads. On the other hand, the radius of the droplets and beads increased as the dripping tip radius increased. The bead radius can easily be predicted by Tate's law equation.

Energy is a key indicator of the nation's overall economic as well as social development. Looking at the present energy demand scenario in Bangladesh, electricity demand has significantly increased over the past years. Most of the Bangladesh's power plants are heavily dependent on expensive imported fossil fuel energy resources. Thus, the power failure has become an acute problem for the country and adversely affects the socio-economic development of the country. Consequently, the shortage and constraint in availability of fossil fuels appeal to boost up the renewable energy sector in Bangladesh in order to bring down the gap between demand and supply. Hence, decisive steps to reform the power sector with a mandate to oversee these sectors urgently need to overcome current energy crisis facing in the country. In this paper, efforts have been made to summarize the availability, current status, strategies, perspectives, promotion policies, major achievements and future potential of energy options in Bangladesh.

The insecure supply of fossil fuel coerces the scientific society to keep a vision to boost investments in the renewable energy sector. Among the many renewable fuels currently available around the world, biodiesel offers an immediate impact in our energy. In fact, a huge interest in related research indicates a promising future for the biodiesel technology. Heterogeneous catalyzed production of biodiesel has emerged as a preferred route as it is environmentally benign needs no water washing and product separation is much easier. The number of well-defined catalyst complexes that are able to catalyze transesterification reactions efficiently has been significantly expanded in recent years. The activity of catalysts, specifically in application to solid acid/base catalyst in transesterification reaction depends on their structure, strength of basicity/acidity, surface area as well as the stability of catalyst. There are various process intensification technologies based on the use of alternate energy sources such as ultrasound and microwave. The latest advances in research and development related to biodiesel production is represented by non-catalytic supercritical method and focussed exclusively on these processes as forthcoming transesterification processes. The latest developments in this field featuring highly active catalyst complexes are outlined in this review. The knowledge of more extensive research on advances in biofuels will allow a deeper insight into the mechanism of these technologies toward meeting the critical energy challenges in future.

This paper presents both experimental and theoretical aspects of the rheological properties and gelling behavior of boehmite suspensions over a range of pH, temperature and concentration. Boehmite sol–gel behaved as a non-Newtonian shear thinning fluid with the increase in consistency index k at lower pH. The flow behavior index (n) representing the relative degree of shear thinning was influenced by pH. The power law theory was used to explain the k and n for gelling behavior and the limit of pseudoplasticity of the boehmite suspensions. It was also found that the variation of activation energy with pH had an appreciable effect on the viscosity of the suspensions. Further it was observed that the density of the suspensions was strongly pH-dependent, with a maximum density at pH 1. Hence, it can be concluded that the rheological properties of colloidal aluminium oxihydroxide (boehmite) suspensions are predominantly affected by the physico-chemical parameters.

Dacryodes species are evergreen, perennial trees with fleshy fruits and belong to the family Buseraseae. Many Dacryodes species are underutilized but are widely applied in traditional folk medicine to treat malaria, fever and skin diseases. The nutritional compositions, phytochemicals and biological activities of Dacryodes edulis, Dacryodes rostrata, Dacryodes buettneri, Dacryodes klaineana and Dacryodes hexandra are presented. The edible fruits of D. edulis are rich in lipids, proteins, vitamins, fatty acids and amino acids. Its extracts (leaf, fruit and resin) exhibit antioxidant, anti-microbial, anti-carcinogenic and other bioactivities. D. rostrata fruit has significant nutrient content, and is rich in proteins, lipids and minerals. These fruits are also highly rich in polyphenols, anthocyanins and antioxidant activities. This comprehensive review will assist the reader in understanding the nutritional benefits of Dacryodes species and in identifying current research needs.

The use of spherical millimetric gamma-alumina (γ-Al2O3) as a catalyst support for the production of biodiesel from palm oil is demonstrated. The catalyst support was produced using a dripping method, and KF and NaNO3 catalysts were loaded on the support using the impregnation method. X-ray diffraction (XRD) analysis showed the formation of Na2O and NaAlO2 phases on the NaNO3/γ-Al2O3 catalyst and the formation of K2O and KAlF4 on the KF/γ-Al2O3 catalyst, which were possibly the active sites for the transesterification reaction. The highest number and strength of basic sites generated from the solid phase reaction of the KF/γ-Al2O3 catalyst loaded with 0.24g kF/g γ-Al2O3 and the NaNO3/γ-Al2O3 catalyst loaded with 0.30g NaNO3/g γ-Al2O3 were confirmed by temperature programmed desorption of CO2 (CO2-TPD) analysis. The nitrogen adsorption-desorption isotherms also revealed a mesoporous structure of the catalysts. The biodiesel yield was comparable to that produced from smaller catalysts, and this result indicated the potential of the macrospherical catalysts

The production of biodiesel is gaining momentum with the ever increasing demand of the fuel. Presently, limited literature is available with respect to well designed solid heterogeneous catalyst for biodiesel production considering all the characteristics, process and operation parameters. Hence, a study was conducted to design effective heterogeneous catalyst for biodiesel production. Further, the significant impact of different catalysts, different feed stock, various reaction conditions such as temperature, methanol oil molar ratio, catalyst concentrations and stability/inactivation of the catalysts, are detailed out for transesterification process of biodiesel production. Based on the studies it can be concluded that well designed heterogeneous catalyst can yield high throughput of biodiesel.

Herein we describe a versatile new strategy for producing spherical solid particles with 2 mm in size using integrated gelling process. The method involves the formation of spherical droplets by using a peristatic pump device and shaping the droplets in a liquid calcium chloride solution. The shape and size of these calcium alginate macroparticles depend strongly on the calcium solution concentration. The shaping mechanism of the macroparticles and the impact of the experimental conditions on particle shape and size are investigated. This method has the following features: (1) A new level of control over the shapes of the particles is offered. (2) The procedure can be scaled up to produce large numbers of particles. (3) The final porous structure of the developed particle can be designed for a specific application (adsorption, catalysis).

The production of biodiesel is gaining momentum with the ever increasing demand of the fuel. Presently, limited literature is available with respect to well designed solid heterogeneous catalyst for biodiesel production considering all the characteristics, process and operation parameters. Hence, a study was conducted to design effective heterogeneous catalyst for biodiesel production. Further, the significant impact of different catalysts, different feed stock, various reaction conditions such as temperature, methanol oil molar ratio, catalyst concentrations and stability/inactivation of the catalysts, are detailed out for transesterification process of biodiesel production. Based on the studies it can be concluded that well designed heterogeneous catalyst can yield high throughput of biodiesel.

The objective of this study was to investigate the effects of process variables on the encapsulation of oil in a calcium alginate membrane using an inverse gelation technique. A dispersion of calcium chloride solution in sunflower oil (water-in-oil emulsion) was added dropwise to the alginate solution. The migration of calcium ions to the alginate solution initiates the formation of a ca-alginate membrane around the emulsion droplets. The membrane thickness of wet capsules and the elastic modulus of dry capsules increased following first-order kinetics with an increasing curing time. An increase in the calcium chloride concentration increased the membrane thickness of wet capsules and the elastic modulus of dry capsules. An increase in the alginate concentration decreased the mean diameter of wet capsules but increased the elastic modulus of dry capsules

Presently microalgae is considered as an alternative biodiesel source and have been cultivated in large scale for commercial use. However, there is lack of efficient systems for mass cultivation of microalgae. In this study. a scaled up 280 L flat panel airlift photobioreactor (FP-ALPBR), based on previous work by Issarapayup and co-workers (lssarapayup, Powtongsook, & Pavasant, 2009), was designed and constructed fiberglass as an alternative system for the large scale outdoor cultivation of microalgae in Malaysia. A local north Borneon strain of Chlore/la sp. was used to assess the growth productivity. The 280 L FP-ALPBR was capable of giving cell productivity of 2.63 x lOs cells mrl d-I, maximum cell density of 6.0 I x 1 06 cells mrl and specific growth rate of 0.15 day-I. The performance of this photobioreactor was compared with the 17 L FP-ALPBR and 90 L FP-ALPBR of the same design. The 280 L FP-ALPBR gave a better performance in terms of maximum cell density, but as expected for large scale it resulted in a considerable decrease in specific growth. This photobioreactor was found to produce a larger harvesting volume and cell density but could not compare in growth rate produced by the smaller 17 L FP-ALPBR and the 90 L FP-ALPBR.

The fuel crisis and environmental concerns, mainly due to global warming, have led researchers to consider the importance of biofuels such as biodiesel. Vegetable oils, which are too viscous to be used directly in engines, are converted into their corresponding methyl or ethyl esters by a process called transesterification. With the recent debates on "food versus fuel," non-edible oils, such as Jatropha curcas, are emerging as one of the main contenders for biodiesel production. Much research is still needed to explore and realize the full potential of a green fuel from J. curcas. Upcoming projects and plantations of Jatropha in countries such as India, Malaysia, and Indonesia suggest a promising future for this plant as a potential biodiesel feedstock. Many of the drawbacks associated with chemical catalysts can be overcome by using lipases for enzymatic transesterification. The high cost of lipases can be overcome, to a certain extent, by immobilization techniques. This article reviews the importance of the J. curcas plant and describes existing research conducted on Jatropha biodiesel production. The article highlights areas where further research is required and relevance of designing an immobilized lipase for biodiesel production is discussed. © 2011 Informa Healthcare USA, Inc.

The formation of κ-carrageenan droplets in channel emulsification was experimentally investigated. The dispersed phase was vertically injected into co-flowing immiscible palm oil in the direction of gravity. This study focused on predicting κ-carrageenan drop size using force balance analysis. The force balance model considers the interfacial tension to be the solitary attaching force, while a combination of the drag force from the co-flowing palm oil and the body force of the extruding κ-carrageenan liquid act as the detaching forces. The conventional model gave poor predictions for droplet size, with an average relative deviation of 23%. This large deviation could be attributed to necking phenomena and an underestimation of the drag force generated on the shear-thinning κ-carrageenan solution. By incorporating correction factors, the average relative deviation of the force balance model dropped to 4%.

The encapsulation of model oil in Ca-alginate beads using high oil loading was studied. It was found that the alginate concentration, oil volume fraction and alginate type each have a significant influence on the encapsulation efficiency and on bead properties. The alginate-oil emulsion, comprising an oil loading up to 30 vol% and 25 g/L of high G alginate solution (equivalent to an oil-to-wall weight ratio of up to 15 g/g), was found to be stable and resulted in an encapsulation efficiency of 90% before drying. The oil-loaded, wet beads were spherical. The encapsulation efficiency was dependent on the degree of cross-linking at the surface of the extruded emulsion droplet as well as on the emulsion stability. The oil extraction profile of dried beads may be related to the structural properties of the beads, which are dependent on both the drying method and the oil loading. The overall encapsulation efficiency after freeze-drying and oven-drying were 90% and 79%, respectively, with an oil content of over 85 wt% for both types of dried beads. The freeze-dried beads were non-oily and free flowing, whereas the oven-dried beads were oily and sticky. The results of this work are compared to those in the literature, and the merits and the drawbacks associated with different methods are discussed.

The main objective of this work is to improve the physical properties of lyophilized calcium (Ca)–alginate beads as a carrier material for the stabilization of encapsulated living cells. Improvements in the sphericity, flowability and mechanical strength of the dried beads were attributed to the filler, which provided structure and reinforcement to the Ca–alginate hydrogel networks, as verified by X-ray microtomography and scanning electron microscopy. A quantitative analysis of the micro-images revealed the less porous nature of the alginate–starch beads compared to the control. The beads with filler were also found to be less hygroscopic. The results also show that the cells encapsulated within the beads with reduced porosity and hygroscopicity were clearly more stable during lyophilization and storage than the control. In conclusion, the qualities of the alginate beads were improved by incorporating the solid filler, and the filler had a significant influence on cell viability during lyophilization and storage.

The main objective of this work is to improve the physical properties of lyophilized calcium (Ca)–alginate beads as a carrier material for the stabilization of encapsulated living cells. Improvements in the sphericity, flowability and mechanical strength of the dried beads were attributed to the filler, which provided structure and reinforcement to the Ca–alginate hydrogel networks, as verified by X-ray microtomography and scanning electron microscopy. A quantitative analysis of the micro-images revealed the less porous nature of the alginate–starch beads compared to the control. The beads with filler were also found to be less hygroscopic. The results also show that the cells encapsulated within the beads with reduced porosity and hygroscopicity were clearly more stable during lyophilization and storage than the control. In conclusion, the qualities of the alginate beads were improved by incorporating the solid filler, and the filler had a significant influence on cell viability during lyophilization and storage.

Rheological studies of boehmite sols based on pH was (1) to study the nature of flow properties of the boehmite sols and (2) to identify the sol-gel transition of boehmite sols with the change of pH of the liquid. It is evident that the shear rate and viscosity of the liquid exhibit a pseudoplastic (shear thinning) flow behavior for all pH level. The transformation of sol-gel at low pH probably due to the hydrogen bond between the layers of the boehmite structure. The temperature has an appreciable effect on the activation energy during the sol-gel transition. The flow activation energies ?E? are in the range of 1.75 to 6.25 J mol-1 at temperature 298-384 K. Based on these results, the flow activation energy of boehmite sols sharply decreases with decreasing the pH. The flocculation of the suspension at pH 4 to 1 showed to be favourable in term of enhanced density of boehmite.

A comparative study on the stability and potential of alginate and pectin based beads for production of poultry probiotic cells using MRS medium in repeated batch fermentation was conducted. The bead cores, made of three types of materials, i.e., ca-alginate, ca-pectinate and ca-alginate/pectinate, were compared. The effect of single and double layer coatings using chitosan and core material, respectively, on the bead stability and cell production were also studied. The pectin based beads were found to be more stable than that of the alginate beads and their stability was further improved by coating with chitosan. The cell concentration in pectin based beads was comparable to that in the alginate beads. On the other hand, pectin based beads gave significantly lower cell concentration in the growth medium for the initial fermentation cycles when compared to the alginate beads. In conclusion, pectin was found to be potential encapsulation material for probiotic cell production owing to its stability and favourable microenvironment for cell growth.

The aim of this work was to determine the effect of formulation of alginate beads on their mechanical behavior and stiffness when compressed at high speed. The alginate beads were formulated using different types and concentrations of alginate and gelling cations and were produced using an extrusion-dripping method. Single wet beads were compressed at a speed of 40 mm/min, and their elastic limits were investigated, and the corresponding force versus displacement data were obtained. The Young's moduli of the beads were determined from the force versus displacement data using the Hertz's contact mechanics theory. The alginate beads were found to exhibit plastic behavior when they were compressed beyond 50% with the exception of copper–alginate beads for which yield occured at lower deformation. Alginate beads made of higher guluronic acid contents and gelling cations of higher chemical affinity were found to have greater stiffness. Increasing the concentration of alginate and gelling ions also generated a similar effect. At such a compression speed, the values of Young's modulus of the beads were found to be in the range between 250 and 900 kPa depending on the bead formulation.

A comparative study on the stability and potential of alginate and pectin based beads for production of poultry probiotic cells using MRS medium in repeated batch fermentation was conducted. The bead cores, made of three types of materials, i.e., ca-alginate, ca-pectinate and ca-alginate/pectinate, were compared. The effect of single and double layer coatings using chitosan and core material, respectively, on the bead stability and cell production were also studied. The pectin based beads were found to be more stable than that of the alginate beads and their stability was further improved by coating with chitosan. The cell concentration in pectin based beads was comparable to that in the alginate beads. On the other hand, pectin based beads gave significantly lower cell concentration in the growth medium for the initial fermentation cycles when compared to the alginate beads. In conclusion, pectin was found to be potential encapsulation material for probiotic cell production owing to its stability and favourable microenvironment for cell growth.

Serum deprivation inhibits cell growth and initiates apoptosis cell death in mammalian cell cultures. Since apoptosis is a genetically controlled cell death pathway, over-expression of anti-apoptotic proteins may provide a way to delay apoptosis. This study investigated the ability of the X-linked inhibitor of apoptosis protein (XIAP) to inhibit apoptosis induced by serum deprivation. Study includes evaluation of the ability of XIAP to prolong culture period and its effect on cell proliferation in serum-deprived media. The full length human XIAP was introduced into CHO-K1 cell lines and the effects of XIAP over-expression on the inhibition of apoptosis induced by serum-deprived conditions were examined. In batch cultures, cells over-expressing XIAP showed decreased levels of apoptosis and a higher number of viable cell under serum-deprived conditions compared to the control cell lines. The viability of control cells dropped to 40% after 2. days of serum deprivation, the XIAP expressing cells still maintained at a viability higher than 90%. Further investigation revealed that the caspase-3 activity of the CHO-K1 cell line was inhibited as a result of XIAP expression. © 2010 The Society for Biotechnology, Japan.

This work deals with the enzymatic transesterification of palm oil with methanol in a solvent-free system. Among the five lipases tested in the initial screening, lipase PS from Burkholderia cepacia resulted in the highest triglyceride conversion. Lipase PS was further investigated in a novel immobilized form by encapsulating within a biopolymer, κ-carrageenan. Using the immobilized lipase the production parameters of biodiesel from palm oil were optimized. The optimal conditions for processing 10 g of palm oil was: 30 °C, 1:7 oil/methanol molar ratio, 1 g water, 5.25 g immobilized lipase, 72 h reaction time and 23.7g relative centrifugal force. At the optimal conditions, triglyceride conversion of up to 100% could be obtained. The immobilized lipase was stable and retained 82% relative transesterification activity after five cycles. Liquid core lipase encapsulated in κ-carrageenan could be a potential immobilized catalyst for eco-friendly production of biodiesel. © 2010 Elsevier Ltd. All rights reserved.

The aim of this work was to develop a standard quantitative method to measure the acid tolerance of probiotic cells when exposed to a simulated gastric fluid. Three model strains of different cell concentrations were exposed to a standard simulated gastric fluid of fixed volume. The fluid pH ranged from pH1.5 to 2.5. In general, the death kinetics followed an exponential trend. The overall death constant, k d, for all strains was found to be in a power relationship with the pH value and the initial cell concentration, and it can be expressed as kd= kAII( pH -9.0N 0-0.19 where k AII is defined as the acid intolerance indicator and N 0 is the initial cell concentration (CFU/ml). This equation was validated with the experimental data with an average R 2 of 0.98. The acid intolerance of cells can be quantitatively expressed by the k AII values, where higher value indicates higher intolerance. In conclusion, a standard quantitative method has been developed to measure the acid tolerance of probiotic cells. This could facilitate the selection of probiotic strains and processing technologies. © 2009 Springer-Verlag.

Serum deprivation inhibits cell growth and initiates apoptosis cell death in mammalian cell cultures. Since apoptosis is a genetically controlled cell death pathway, over-expression of anti-apoptotic proteins may provide a way to delay apoptosis. This study investigated the ability of the X-linked inhibitor of apoptosis protein (XIAP) to inhibit apoptosis induced by serum deprivation. Study includes evaluation of the ability of XIAP to prolong culture period and its effect on cell proliferation in serum-deprived media. The full length human XIAP was introduced into CHO-K1 cell lines and the effects of XIAP over-expression on the inhibition of apoptosis induced by serum-deprived conditions were examined. In batch cultures, cells over-expressing XIAP showed decreased levels of apoptosis and a higher number of viable cell under serum-deprived conditions compared to the control cell lines. The viability of control cells dropped to 40% after 2days of serum deprivation, the XIAP expressing cells still maintained at a viability higher than 90%. Further investigation revealed that the caspase-3 activity of the CHO-K1 cell line was inhibited as a result of XIAP expression.