Synthesis Of Fatty Acid Ethyl Esters Research Articles

The Physicochemical Basis for the Production of Rapeseed Oil Fatty Acid Esters in a Plug Flow Reactor

This article describes the results of a comprehensive comparative study of the production of fatty acid ethyl esters (FAEEs) for use as biodiesel in perfect mixing reactors (PMRs) and plug flow reactors (PFRs). The products obtained on a laboratory scale at all stages of the separation and purification of the FAEE phase were analyzed using the FTIR, XRF and GC-MS methods. We compared distillation methods for the separation of stoichiometrically excessive ethanol from the reaction mixture. Neutralization methods with H2SO4 solution and carbonation with CO2 were applied for FAEE phase purification from the catalyst. Emulsions formed during the water flushing stage were analyzed via the optical microscopy method. The optimal conditions of stirring speed and temperature were selected to maintain a high level of FAEE–water phase contact area with minimum phase separation time. The efficiency of the carbonation method for catalyst neutralization in the FAEE phase has been proven, allowing us to consider this method as an alternative to the traditional acid neutralization method. According to the results of experimental studies, we have developed a new high-performance technological scheme for the production of fatty acid esters in PFRs. The synthesis of FAEEs in a stoichiometric excess of ethanol of about 1:50 allowed us to increase the reaction rate and productivity of the synthesis unit after the transition from a PMR to a PFR. The yield of the product amounted to 86.7%. The purified FAEE fraction complied with most EN14214 specifications.

Green synthesis of metal oxides (CaO-K2O) catalyst using golden apple snail shell and cultivated banana peel for production of biofuel from non-edible Jatropha Curcas oil (JCO) via a central composite design (CCD)

The use of biomass as a renewable, sustainable, and eco-friendly energy source is now widely recognized as a potential solution for a variety of environmental problems. To develop biodiesel production, cost-effective feedstocks such as agricultural waste, food waste, and non-edible/waste cooking oil were utilized. A heterogeneous solid base catalyst was synthesized by calcining a mixture of waste golden apple snail shell (Pomacea canaliculata) and cultivated (Musa sapientum) banana peel. In transesterification process, potassium oxide (K2O) derived from banana peel is used as a cocatalyst to improve the catalytic activity of calcium oxide (CaO) catalyst derived from waste shell. The innovative CaO-K2O catalyst was investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF) and the Brunauer-Emmett-Teller (BET) technique. The morphology and elemental composition of calcium (Ca), potassium (K), and oxygen (O) in the catalyst were validated by field emission-scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX). The CaO catalyst exhibited a BET surface area of 10.88 m2/g, which was enhanced to 14.62 m2/g upon combination with K2O. The Hammett indicator of CaO catalyst fell between 7.2 < H_< 9.8. However, the CaO-K2O catalyst exhibited a higher value of 15.0 < H_< 18.4, which could be attributed to the phase transition from CaO to CaO-K2O. To investigate the effects of catalyst concentration, ethanol/oil molar ratio, and transesterification time on the yield of fatty acid ethyl ester (FAEE). The optimal conditions for FAEE synthesis were determined using a central composite design (CCD) approach with response surface methodology (RSM). The regression equation obtained for the CCD model has a determination coefficient (R2) of 0.9921, indicating that this model is well-fitted. At 3.69 wt% catalyst concentration, 19.48:1 ethanol/oil molar ratio, and 1.80 h transesterification time, the highest FAEE yield from Jatropha Curcas oil (JCO) of 97.06 % was obtained. The novel catalyst has a strong yield and can be utilized for up to 6 cycles. It was found that the corresponding yield was 90 % when employing the same process parameters, demonstrating the high reusability of this catalyst. The biodiesel produced from non-edible JCO meets the criteria for standard biodiesel (ASTM D-6751 and EN 14214). The CaO-K2O catalyst is inexpensive, easy to make, biodegradable, recyclable, and environmentally friendly because it is derived from a biological residue. Because of these characteristics, it may be an appropriate candidate for the role of “green catalyst” in sustainable energy production.

Insights into whereby raw wheat Qu contributes to the flavor quality of Huangjiu during brewing

The influence of raw wheat Qu (RWQ) on the flavor quality of Huangjiu was investigated in this study. When used as a single saccharification starter, RWQ showed poor fermentation performance during Huangjiu brewing. However, as a co-fermentation starter with cooked wheat Qu (CWQ), RWQ considerably enhanced flavor quality of the resultant Huangjiu by promoting the accumulation of fatty acid ethyl esters (FAEEs) with odor activity values exceeding 1. Based on dynamic changes in bacterial diversity during Huangjiu brewing, a three-stage fermentation mode was identified for the first time. During stage III (5–15 d), the relative proportions of predominant genera Weissella and Lactococcus, which were strongly associated with the synthesis of FAEEs, were significantly adjusted by the co-fermentation of RWQ with CWQ. Moreover, co-fermentation of RWQ with CWQ reduced the bacterial diversity of Huangjiu samples, and this was strongly related to the total acidity (R2 = 0.867) and ethanol (R2 = 0.802) content. Therefore, the proportions of predominant bacteria were changed by RWQ, which affected bacterial diversity and enhanced the flavor quality of Huangjiu. Controlling environmental factors during brewing is suggested as a feasible way to regulate the proportions of bacterial genera, thereby regulating the flavor characteristic in the resultant wine.

Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism.

Fatty acid ethyl esters are important flavor chemicals in strong-flavor baijiu. Microorganisms are the main contributors to ester synthesis during baijiu manufacture. However, the ester synthesis was unstable between batches. This was owing to a limited knowledge of the mechanisms for ester synthesis by microorganisms. In this work, a fatty acid ethyl ester synthesizing Aspergillus niger strain CGMCC (China General Microbiological Culture Collection) 3.4309 was identified. The conversion ratios of ethyl valerate, ethyl caproate, ethyl caprylate, and ethyl caprate were 7.87, 29.20, 94.80, and 85.20%, respectively, under the optimized conditions. A comparison of transcriptomes under the initial and optimized ester synthetic conditions indicated that 23 genes were upregulated in transcription level and encoded enzymes with potential abilities for ester synthesis. Eleven of the enzymes were expressed, and three of them, numbered An605, An1097, and An3131, showed the ability to catalyze fatty acid ethyl ester synthesis under aqueous phase, with capric acid as the preferred substrate. The possible enzymatic catalytic mechanism was proposed based on homology modeling and molecular docking. This study reported for the first time that A. niger showed the ability to efficiently catalyze the synthesis of short- and medium-chain fatty acid ethyl esters in aqueous phase, identified the key enzymes, and analyzed the basic enzymatic properties. This is helpful to promote the application of related microorganisms and enzyme resources in the baijiu industry.

Metabolic engineering Yarrowia lipolytica for a dual biocatalytic system to produce fatty acid ethyl esters from renewable feedstock in situ and in one pot.

Given the grave concerns over increasing consumption of petroleum resources and dramatic environmental changes arising from carbon dioxide emissions worldwide, microbial biosynthesis of fatty acid ethyl ester (FAEE) biofuels as renewable and sustainable replacements for petroleum-based fuels has attracted much attention. As one of the most important microbial chassis, the nonconventional oleaginous yeast Yarrowia lipolytica has emerged as a paradigm organism for the production of several advanced biofuels and chemicals. Here, we report the engineering of Y. lipolytica for use as an efficient dual biocatalytic system for in situ and one-pot production of FAEEs from renewable feedstock. Compared to glucose with 5.7% (w/w) conversion rate to FAEEs, sunflower seed oil in the culture medium was efficiently used to generate FAEEs with 84% (w/w) conversion rate to FAEEs by the engineered Y. lipolytica strain GQY20 that demonstrates an optimized intercellular heterologous FAEE synthesis pathway. In particular, the titer of extracellular FAEEs from sunflower seed oil reached 9.9 g/L, 10.9-fold higher than that with glucose as a carbon source. An efficient dual biocatalytic system combining ex vivo and strengthened in vitro FAEE production routes was constructed by overexpression of a lipase (Lip2) variant in the background strain GQY20, which further increased FAEEs levels to 13.5 g/L. Notably, deleting the ethanol metabolism pathway had minimal impact on FAEE production. Finally, waste cooking oil, a low-cost oil-based substance, was used as a carbon source for FAEE production in the Y. lipolytica dual biocatalytic system, resulting in production of 12.5 g/L FAEEs. Thus, the developed system represents a promising green and sustainable process for efficient biodiesel production. KEY POINTS: • FAEEs were produced by engineered Yarrowia lipolytica. • A Lip2 variant was overexpressed in the yeast to create a dual biocatalytic system. • Waste cooking oil as a substrate resulted in a high titer of 12.5 g/L FAEEs.

Water Addition During Oil Extraction Affects on Virgin Olive Oil Ethanol Content, Quality and Composition

AbstractEthanol is the alcoholic precursor of fatty acid ethyl esters (FAEEs) in virgin olive oil (VOO). Because of its miscibility, water addition during oil extraction may affect oil ethanol content and then, the FAEEs synthesis during oil storage. In this work, the effect of water addition on VOO ethanol content and composition is studied. Water addition at two extraction systems (two and three phases) is compared and for vertical centrifuge, water addition at different temperatures is assayed. Ethanol content, quality parameters, and healthy components are determined in the oils. Results indicate three phase system gives oils with a 25% lower ethanol content than two phases. Ethanol reduction because of water addition is more important for three phases system (≈14%). For vertical centrifugation, ethanol is lowered as water dose and temperature increase. In general, water addition for any of the extraction steps analyzed reduces the oil ethanol concentration but other aspects such as fruity intensity and phenol content are also lowered.Practical applications: Virgin olive oil final ethanol content, and then its FAEEs concentration, does not only depend on the health and conservation status of olives, but also on the extraction system used and the amount of water added to the extraction process. The knowledge of the impact on ethanol content of water addition during oil extraction can be useful for olive oil legislators in order to keep the approved limits of FAEEs or to modify them. For oil producers, results can help to reduce the oil ethanol content and then FAEEs synthesis during virgin olive oil storage.

Ester Group Detection of Biodiesel from Used Cooking Oil with Sulphuric and Toluene Sulphuric Acid Catalysts

Used cooking oil is potential as raw material to produce biodiesel. We discovered fatty acid ethyl esters (FAEEs) and methyl esters (FAMEs) as biodiesel content indicator from esterification and trans-esterification reactions of used cooking oil with sulphuric acid and toluene sulphuric acid as catalysts. The purpose of this study was to examine some characteristics of FAEE and FAME synthesis from used cooking oil. The FAEEs and FAMEs were detected by separation in thin layer chromatography (TLC) and Fourier Transform Infrared (FT-IR) and compared to laurate standar. The used cooking oil was produced after frying of meat chicken for seven hours in a household. The Retardation Factor (Rf) of TLC of FAME of methyl laurate was 0.36 and FAEE of ethyl laurate was 0.23. The wavenumber indicating specific functional group of =CH was 3392 cm-1, while of alcohol as ester compound was 1739.79 cm-1. The wavenumber of C-C and CO groups were 1635.64 cm-1and 1165 cm-1, respectively. These indicate the ester group in used cooking oil, which reflects the formation of bio-diesel.

Activation of AMP-activated protein kinase attenuates ethanol-induced ER/oxidative stress and lipid phenotype in human pancreatic acinar cells

Primary toxicity targets of alcohol and its metabolites in the pancreas are cellular energetics and endoplasmic reticulum (ER). Therefore, the role of AMP-Activated Protein Kinase (AMPKα) in amelioration of ethanol (EtOH)-induced pancreatic acinar cell injury including ER/oxidative stress, inflammatory responses, the formation of fatty acid ethyl esters (FAEEs) and mitochondrial bioenergetics were determined in human pancreatic acinar cells (hPACs) and AR42J cells incubated with/without AMPKα activator [5-aminoimidazole-4-carboxamide ribonucleotide (AICAR)]. EtOH treated hPACs showed concentration and time-dependent increases for FAEEs and inactivation of AMPKα, along with the upregulation of ACC1 and FAS (key lipogenic proteins) and downregulation of CPT1A (involved β-oxidation of fatty acids). These cells also showed significant ER stress as evidenced by the increased expression for GRP78, IRE1α, and PERK/CHOP arm of unfolded protein response promoting apoptosis and activating p-JNK1/2 and p-ERK1/2 with increased secretion of cytokines. AR42J cells treated with EtOH showed increased oxidative stress, impaired mitochondrial biogenesis, and decreased ATP production rate. However, AMPKα activation by AICAR attenuated EtOH-induced ER/oxidative stress, lipogenesis, and inflammatory responses as well as the formation of FAEEs and restored mitochondrial function in hPACs as well as AR42J cells. Therefore, it is likely that EtOH-induced inactivation of AMPKα plays a crucial role in acinar cell injury leading to pancreatitis. Findings from this study also suggest that EtOH-induced inactivation of AMPKα is closely related to ER/oxidative stress and synthesis of FAEEs, as activation of AMPKα by AICAR attenuates formation of FAEEs, ER/oxidative stress and lipogenesis, and improves inflammatory responses and mitochondrial bioenergetics.

Uncovering mechanisms of greengage wine fermentation against acidic stress via genomic, transcriptomic, and metabolic analyses of Saccharomyces cerevisiae.

Acid stress is one of the most common adverse conditions during fermentation of fruit wines, and the acid tolerance of yeasts is, therefore, critical for fruit wine production. However, the biological mechanism underlying the acquired tolerance of yeasts against acid stress is poorly understood. We have previously obtained an evolved Saccharomyces cerevisiae strain ET008-c54 with increased tolerance against acid stress, and potentially, it serves as a promising yeast strain for greengage wine fermentation. In the current study, we further revealed the alterations responsible for the adaptation of ET008-c54 to low pH by whole-genome re-sequencing, transcriptomic, and metabolic analyses. Results confirmed the outstanding fermenting performance of ET008-c54 at low pH as compared with the parental ET008. More specifically, the growth rate of ET008-c54 at low pH was increased by 6.24 times and the fermentation time was shortened by 70%. Differences were also observed in the physiology of the strains through ergosterol, H+-ATPase activity, and aroma determinations. By integrating both RNA-seq and whole-genome re-sequencing data, we demonstrated some metabolic pathways in ET008-c54, namely ergosterol synthesis and ferrous iron uptake, in which several acid-responsive genes were involved being upregulated. Also, upregulation of the pathways responsible for aroma compound formation, including fatty acid ethyl ester synthesis and aromatic amino acid biosynthesis, was identified. Thus, the enhanced fermentation ability of ET008-c54 at low pH should be, at least partly, contributed by the altered gene expressions associated with the aforementioned pathways. By elucidating the biological mechanism of yeasts against acid stress, this current study allows better-defined targets for future studies of genetic improvement of wine yeasts and enhancement of the fermentation processes. KEY POINTS: • Metabolic analysis confirmed the excellent fermentation performance of ET008-c54. • Acid tolerance genes for ergosterol synthesis and ferrous iron uptake were upregulated. • Aroma genes for fatty acid ethyl ester and aromatic amino acid synthesis were upregulated.

Ultrasound affects the selectivity and activity of immobilized lipases applied to fatty acid ethyl ester synthesis

Hydrophobic carriers can be used to improve the activity, stability and other properties of enzymes. Physical agents, like ultrasound, may also contribute to improving the dispersion and collision of the reagent molecules, decreasing the reaction time and intensifying the catalytic process. However, its effect on the enzyme activity and reaction selectivity is still not entirely understood. Here, enzyme modulation of immobilized lipases was studied under pulsed ultrasound irradiation in fatty acid ethyl ester (FAEE) synthesis for biodiesel production. Novozym 435® and two commercial lipases from Thermomyces lanuginosus and Rhizomucor miehei, immobilized on Octadecyl-Sepabeads were used as a biocatalyst in the transesterification reaction of vegetable oils and ethanol. The use of ultrasound associated with catalysis by the Novozym 435 increased the production of FAEE by about three times (from 8.9 to 26.4%) using soybean oil and changes were observed in the profile of the products. From the sonicated reaction, ethyl-palmitate production decreased from 23.4 to 11.7%, while the ethyl-linoleate content rose from 47.5 to 59.2%. On the other hand, the T. lanuginosus lipase was less affected by sonication with the overall production of FAEE increasing from 17.2 to 24.1%, with ethyl-palmitate and ethyl-linoleate content changing from 16.2 to 17.5% and 55.0 to 47.8%, respectively. Although the changes in the production yield are not too high, the main idea here was to show that ultrasound modulates the lipase activity as well as its respective selectivity. Thus, ultrasound, is responsible for changing the ethyl ester production, which can be applied to many other biochemical processes to improve or modulate their synthesis yield.

Green Biodiesel Production from Various Plant Oils Using Nanobiocatalysts Under Different Conditions

The lipase-immobilized polyethyleneimine (PEI)- and polyacrylic acid (PAA)–coated magnetic silica nanocomposite particles (L-PEI-MS and L-PAA-MS, respectively) were prepared and applied at various transesterification reaction conditions. The reactions were carried out with soybean, sunflower, canola, and palm oils along with methanol or ethanol in the solvent-free and n-hexane systems. The highest fatty acid methyl ester (FAME) and fatty acid ethyl ester (FAEE) synthesis yields were obtained from the transesterification of palm oil, i.e., almost 7.7–10.2% higher than other oils. At the constant reaction conditions, the application of ethanol leads to higher (6.0–8.7%) reaction yields in comparison with methanol. In addition, irrespective of reaction conditions, the best performance was acquired by L-PEI-MS; e.g., the FAME and FAEE synthesis yield values of 81.2% and 88.3% were obtained from transesterification of palm oil in the solvent-free systems, respectively. Addition of n-hexane improved the synthesis of FAME and FAEE yield values to 88.9% and 93.3%, respectively, using L-PEI-MS. The transesterification reactions kinetics follows the Ping-Pong Bi-Bi mechanism with alcohol inhibition effects. The high catalytic performance of L-PEI-MS might be related to its hydrophobic nature, which enhances the accessibility of oil molecules to the immobilized lipases and hampers the deactivating effect of alcohol molecules on them.

A novel clean process for the combined production of fatty acid ethyl esters (FAEEs) and the ethyl ester of polyunsaturated fatty acids (PUFAs) from microalgae oils

Although the methanolysis of microalgae oil for biodiesel preparation was studied previously, the ethanolysis for the combined production of fatty acid ethyl esters (FAEEs, also can be used as biodiesel) and the ethyl esters of PUFAs (an important health-care product) rarely reported. In this work, a novel two-step process, hydrolysis of microalgae oil followed by lipase-mediated ethanolysis, was developed for the synthesis of FAEEs and the ethyl ester of PUFAs. The hydrolysis was firstly performed and the generated free fatty acids was collected and further used for FAEEs synthesis catalyzed by lipase. For lipase-catalyzed ethanolysis, the adding strategy of methanol, molecular sieve dosage, lipase dosage and temperature had significant influence on the FAEE yield. Under the optimized conditions, a FAEE yield of 97% could be obtained. Novozym435 was found to be equally effective for catalyzing the ethanolysis of conventional free fatty acids and PUFAs. The combined effects of multiple factors on the ethanolysis was further studied using Response Surface Methodology (RSM). Validation statistical analysis suggested that the negative correlation existed between FAEE yield and the water content. This work provided a novel strategy to produce FAEEs and the ethyl esters of PUFA effectively with microalgae oil as the substrate.

Engine performance and emission of biodiesel fuel prepared from different Ukrainian natural oils

A range of natural oils such as rapeseed, sunflower, corn, linseed, and mustard ones has been used for fatty acid ethyl esters synthesis. The last as pure biodiesel B100 were mixed with fossil diesel B0 to form blends B20, B40, B60, and B80. This study reports the effects of engine load and biodiesel percentage on the performance and emission of a tractor diesel engine fueled with biodiesel–diesel blends. It is stated that mixed fuels little inferior to mineral diesel in engine performance, but the observed reduction is not critical. The results showed that the engine performance (effective power and torque) depends primarily on the content of acids with C18 carbon chain in the oil. It was also found that the highest performance among the blended fuels is introduced by ethyl esters of rapeseed oil, while corn and mustard oil ethyl esters presented the lowest emissions level. The emissions of rapeseed, sunflower, corn, linseed, and mustard ethyl esters are all lower than the base mineral fuel.

Enzymatic fatty acid ethyl esters synthesis using acid soybean oil and liquid lipase formulation

Acid oils represent a low-cost feedstock for biodiesel synthesis. The aim of this work was to study a single-step enzymatic esterification and transesterification process for fatty acid ethyl esters (FAEEs) production employing acid oils, ethanol, and liquid lipase formulation. The effects of lipase source (CALB, Palatase 20000 L, Lipolase 100 L, and Callera Trans L), temperature and enzyme ratio were studied in the transesterification of refined soybean oil with ethanol. The highest yield esters content (97%) was obtained at 30 °C with 10% vol/vol of Lipolase 100 L. The ethanolysis of acid soybean oil, using soybean oils with different acid contents (acid value (AV): 8.5, 50, and 90), was investigated using 10% vol/vol of lipase at 30 °C. The highest esters content (71%) was obtained employing acid oil with AV 50 and Palatase 20,000 L. The results showed the significant performance of soluble lipases in transesterification reactions of acid oils aiming for FAEEs synthesis.

Effect of lanthanide ion doping on Mg−Al mixed oxides as active acid−base catalysts for fatty acid ethyl ester synthesis

Abstract MgAl-hydrotalcites (HT) containing 1–2% of the lanthanide ions La3+, Ce3+ and Lu3+ were evaluated as heterogeneous catalysts in the transesterification process for fatty acid ethyl ester (FAEE) synthesis in order to understand the effect of the high ionic-radii of these metals in the material structure and their catalytic activity. The addition of lanthanides to the catalysts resulted in a decrease of the thermal degradation temperature as well as the specific surface, but, on the other hand, it increases the basicity, crystallinity, and improve the yield in biodiesel production. In general, MMOs with 1% of lanthanides showed higher yields than those with 2%, and the oxide with 1% of Lu3+ reached the best catalytic result for ethanol biodiesel production (84%), about 4.5 times greater than the reference material.

Overproduction of Fatty Acid Ethyl Esters by the Oleaginous Yeast Yarrowia lipolytica through Metabolic Engineering and Process Optimization.

Recent advances in the production of biofuels by microbes have attracted attention due to increasingly limited fossil fuels. Biodiesels, especially fatty acid ethyl esters (FAEEs), are considered a potentially fully sustainable fuel in the near future due to similarities with petrodiesels and compatibility with existing infrastructure. However, biosynthesis of FAEEs is limited by the supply of precursor lipids and acetyl-CoA. In the present study, we explored the production potential of an engineered biosynthetic pathway coupled to the addition of ethanol in the oleaginous yeast Yarrowia lipolytica. This type of yeast is able to supply a greater amount of precursor lipids than species typically used. To construct the FAEEs synthesis pathway, WS genes that encode wax ester synthases (WSs) from different species were codon-optimized and heterologously expressed in Y.lipolytica. The most productive engineered strain was found to express a WS gene from Marinobacter hydrocarbonoclasticus strain DSM 8798. To stepwisely increase FAEEs production, we optimized the promoter of WS overexpression, eliminated β-oxidation by deleting the PEX10 gene in our engineered strains, and redirected metabolic flux toward acetyl-CoA. The new engineered strain, coupled with an optimized ethanol concentration, led to an approximate 5.5-fold increase in extracellular FAEEs levels compared to the wild-type strain and a maximum FAEEs titer of 1.18 g/L in shake flask cultures. In summary, the present study demonstrated that an engineered Y.lipolytica strain possessed a high capacity for FAEEs production and may serve as a platform for more efficient biodiesel production in the future.

Synthesis of fatty acid ethyl esters with conventional and microwave heating systems using the free lipase B from Candida antarctica

Free Candida antarctica lipase B (Lipozyme, CALB L®) was used to produce fatty acid ethyl esters (FAEE) from refined soybean oil in solvent-free media using the conventional (CHS) and microwave (MHS) heating systems. Statistical analyses (95% confidence level) for both reaction products, FAEE and free fatty acids (FFA), were performed. An increase in ethanol:oil molar ratio decreased the catalytic performance of CALB L (p < .05). The best conditions using the microwave radiation were a molar ratio of ethanol:oil of 3:1, a water content of 20.3 wt.% and an enzyme loading of 3 wt.% and this resulted in a total ester content of 64.7% in 15 min, while the same condition using the conventional heating gave only 21.4%. Moreover, the reaction equilibrium was reached 16 times faster with microwave than with conventional heating. High ethanol:oil molar ratios had a negative effect on FAEE synthesis with both CHS and MHS, probably due to the partial inactivation of the enzymes. MHS improved the reaction performance of CALB L, but other process parameters will have to be optimized to enhance the resulting FAEE yields. The recovery and reuse of CALB L using a MHS was demonstrated. Hence, the use of microwave radiation under the conditions applied in this study was not detrimental to the catalytic performance of CALB L for at least one reuse.

THE USE OF DOMESTIC MICROWAVE OVEN AND BLENDER IN BIODIESEL SYNTHESIS

We propose in this study the use of household appliances, microwave oven and household blender without adaptation, in fatty acid ethyl ester synthesis from the transesterification of waste frying oil for use in chemistry lessons at different levels of education. The advantage in using the microwave oven, in particular, is in reducing reaction time by almost 10 times compared to traditional experiments. Furthermore, the use of such appliances without adjustments, both of the oven as the blender, eliminates the need for sophisticated equipment and glassware high cost. The success of the reaction, even in these conditions, can be noticed by CCD analysis and 1H NMR spectrum. The realization of biodiesel synthesis in the classroom with the aforementioned tools allows relating chemical concepts such as transesterification reactions, saponification, combustion, stoichiometry and catalysis with environmental issues surrounding sustainable development, recycling and biofuel.

The role of fat and alcohol in acute pancreatitis: A dangerous liaison.

Excessive alcohol consumption is a major trigger for severe acute pancreatitis which may lead to multi-organ dysfunction and premature death of the individual. Hyperlipidaemia is a risk factor for both acute and chronic pancreatitis and the role of fatty acids in mediating damage has received increasing attention in recent years. In the pancreas ethanol is metabolised by both oxidative and non-oxidative pathways. The latter, predominant route generates fatty acid ethyl esters (FAEEs) from fatty acid substrates via the action of diverse enzymes called FAEE synthases, including carboxylester lipase an enzyme synthesized and secreted by the acinar cells. Inhibition of the oxidative pathway promotes formation of FAEEs which induce sustained elevations of cytosolic calcium leading to inhibition of mitochondrial function, loss of ATP and necrosis of isolated pancreatic acinar cells. Furthermore, FAEEs undergo hydrolysis in the mitochondria releasing free fatty acids that exert toxic effects. Our recent work has shown that pharmacological inhibition of carboxylester lipase ameliorated detrimental effects of non-oxidative ethanol metabolism in isolated pancreatic acinar cells invitro and in a new invivo experimental model of alcoholic acute pancreatitis, revealing a specific enzyme target for ethanol-induced injury. Strategies that prevent FAEE synthesis, protect mitochondria, reduce calcium overload or sustain calcium homeostasis by ATP provision may provide promising therapeutic avenues for the treatment of alcoholic acute pancreatitis.

Synthesis of FAEEs from glycerol in engineered Saccharomyces cerevisiae using endogenously produced ethanol by heterologous expression of an unspecific bacterial acyltransferase

The high price of petroleum-based diesel fuel has led to the development of alternative fuels, such as ethanol. Saccharomyces cerevisiae was metabolically engineered to utilize glycerol as a substrate for ethanol production. For the synthesis of fatty acid ethyl esters (FAEEs) by engineered S. cerevisiae that utilize glycerol as substrate, heterologous expression of an unspecific acyltransferase from Acinetobacter baylyi with glycerol utilizing genes was established. As a result, the engineered YPH499 (pGcyaDak, pGupWs-DgaTCas) strain produced 0.24 g/L FAEEs using endogenous ethanol produced from glycerol. And this study also demonstrated the possibility of increasing FAEE production by enhancing ethanol production by minimizing the synthesis of glycerol. The overall FAEE production in strain YPH499 fps1Δ gpd2Δ (pGcyaDak, pGupWs-DgaTCas) was 2.1-fold more than in YPH499 (pGcyaDak, pGupWs-DgaTCas), with approximately 0.52 g/L FAEEs produced, while nearly 17 g/L of glycerol was consumed. These results clearly indicated that FAEEs were synthesized in engineered S. cerevisiae by esterifying exogenous fatty acids with endogenously produced ethanol from glycerol. This microbial system acts as a platform in applying metabolic engineering that allows the production of FAEEs from cheap and abundant substrates specifically glycerol through the use of endogenous bioethanol.