Production Of Esters Research Articles

Biocatalyzed Transesterification of Waste Cooking Oil for Biodiesel Production Using Lipase from the Amazonian Fungus Endomelanconiopsis endophytica

The demand for biodiesel worldwide is skyrocketing as the need to replace fossil diesel with renewable energy sources becomes increasingly pressing. In this context, biocatalysis is emerging as an environmentally friendly and highly efficient alternative to chemical catalysis. When combined with the utilization of waste materials, it has the potential to make the process of biodiesel production sustainable. In the study, the potential of an extract rich in lipase produced by an Amazonian endophytic fungus as a biocatalyst in the transesterification of waste cooking oil for biodiesel production has been systematically investigated. The fungus Endomelanconiopsis endophytica exhibited an enzyme production of 11,262 U/mL after 120 h of cultivation. The lipolytic extract demonstrated its highest catalytic activity at 40 °C and a pH of 5.5. Using soybean oil and frying residue as raw materials, biodiesel was produced through biocatalytic transesterification, and yields of 91% and 89% (wt.), respectively, were achieved. By evaluating the process parameters, a maximum biodiesel yield of 90% was achieved using ethanol at a ratio of 3:1 ratio within 120 min. The experimental results demonstrate the feasibility and sustainability of applying a fungal enzymatic extract as a biocatalyst in the production of ethyl esters using waste cooking oil as a raw material.

Synthesis of cellulose nitrates from Miscanthus × giganteus var. KAMIS cellulose obtained under pilot production conditions

The work is devoted to the study of a novel national raw material resource Miscanthus × Giganteus var. KAMIS, which is positioned as one of the most promising natural sources for obtaining high-quality cellulose for the purpose of its further chemical functionalisation. A batch of technical cellulose isolated from raw materials under pilot production conditions using the nitric acid method having a cellulose content of 50.2% was characterized by high α-cellulose mass fraction (92.8%) and degree of polymerisation (1200) values. On the basis of the pilot batch of technical cellulose, a sample of cellulose nitrates offering basic functional properties was obtained: mass fraction of nitrogen – 11.18%; viscosity – 48 MPa·s; solubility – 94%. The synthesised sample is characterized by extremely high solubility in acetone, confirming the production of cellulose nitric acid esters, and a high yield of 150%. IR-Fourier spectroscopy was used to identify the main functional groups in the experimental batch of technical cellulose (3384, 2902, 1639, 1428, 1370, 1319, 1161, 700–500 cm-1) and in a sample of cellulose nitrates (1659, 1278, 834, 746, 683 cm-1). Acorresponding affiliation to cellulose and cellulose nitric acid esters was established. The structural and morphological features of the fibres of the experimental batch of technical cellulose and a sample of cellulose nitrates were characterised using scanning electron microscopy. Combined methods of thermogravimetric and differential thermal analyses were used to establish high initial temperature (197 °C) and specific heat of decomposition (6.92 kJ/g) values at the beginning of intensive decomposition. The obtained results substantiate the possibility to chemically functionalise cellulose isolated from a new alternative source into cellulose nitric acid esters with satisfactory functional properties.

Nitric oxide reapplication during controlled atmosphere storage impacts on oxidative stress and volatiles production in 'Cripps Pink' apples

The aim of this study was to evaluate the effect of different concentrations of nitric oxide (NO) reapplied during controlled atmosphere (CA) storage on oxidative stress defense mechanisms and on profile of volatile compounds of 'Cripps Pink' apples. Fruit were treated with NO at 0, 1, 2, 5, or 10 μL L−1 every seven days during CA storage (0.8 kPa of O2, <0.5 kPa of CO2, at temperature of 1.5 ± 0.2 °C, and 94 ± 2% RH). Fruit were evaluated after 8 months of CA storage, followed by seven days of shelf life. In general, linear and quadratic models adjusted to quantitative levels of NO showed increased contents of total phenolic compounds (in the pulp and peel tissues), increased activity of catalase, reduced activity of lipoxygenase, reduced content of H2O2, reduced lipid peroxidation and ethylene production in the fruit with the increase of NO concentrations. NO treatment had no effect in the total antioxidant activity and in the activity of the enzymes superoxide dismutase and peroxidase in the fruit. The increase of NO concentrations reduced the volatile compounds butyl acetate, hexyl acetate, 2-methylbutyl acetate, ethyl butanoate, til 2-methylbutanoate, and 1-butanol in the pulp of the fruit. The results show that weekly application of NO at ∼6 μL L−1 during CA storage of 'Cripps Pink' apples improved the mechanisms to protect the fruit from oxidative stress, but it might impair the production of the main esters associated with aroma.

Using ZnAl–LDH@SiO2 as a catalyst for the electrocatalytic conversion of waste frying oil into biodiesel

In this study, a novel electrocatalytic conversion system via simultaneous esterification and transesterification, based on a ZnAl–layered double hydroxide (LDH)@SiO2, was investigated for fatty acid methyl ester (FAME) production from waste frying oil (WFO). A mechanism is proposed for the (trans)esterification process to generate CH3O− and OH− on the ZnAl–LDH@SiO2 as the semiconductor heterogeneous catalyst. The inclusion of SiO2 enhanced the catalyst's basicity and caused a better exposure of atoms of oxygen atoms on the catalyst's surface which contributed to the formation of methoxides as a nucleophilic attack on the triglyceride's carbonyl. Also, ZnAl–LDH@SiO2 as an electrocatalyst reduces the beginning potential rate and increases the charge carriers transport. The results showed that 98.4% FAME yield was obtained at higher water content from WFO after 90 min of reaction at 25 °C using 2 wt% of the ZnAl–LDH@SiO2 catalyst, and a methanol to WFO (M:WFO) molar ratio of 6:1. ZnAl–LDH@SiO2 was also effective for WFO containing 3.3 wt% of free fatty acid (FFA), and indicated high stability for WFO (trans)esterification after 5 runs. The electrocatalytic conversion system has the potential to advance a new process development for the conversion of feedstock containing high FFA and water to produce the second generation of biodiesel.

Reviewing the Source, Physiological Characteristics, and Aroma Production Mechanisms of Aroma-Producing Yeasts.

Flavor is an essential element of food quality. Flavor can be improved by adding flavoring substances or via microbial fermentation to impart aroma. Aroma-producing yeasts are a group of microorganisms that can produce aroma compounds, providing a strong aroma to foods and thus playing a great role in the modern fermentation industry. The physiological characteristics of aroma-producing yeast, including alcohol tolerance, acid tolerance, and salt tolerance, are introduced in this article, beginning with their origins and biological properties. The main mechanism of aroma-producing yeast is then analyzed based on its physiological roles in the fermentation process. Functional enzymes such as proteases, lipases, and glycosidase are released by yeast during the fermentation process. Sugars, fats, and proteins in the environment can be degraded by these enzymes via pathways such as glycolysis, methoxylation, the Ehrlich pathway, and esterification, resulting in the production of various aromatic esters (such as ethyl acetate and ethyl caproate), alcohols (such as phenethyl alcohol), and terpenes (such as monoterpenes, sesquiterpenes, and squalene). Furthermore, yeast cells can serve as cell synthesis factories, wherein specific synthesis pathways can be introduced into cells using synthetic biology techniques to achieve high-throughput production. In addition, the applications of aroma yeast in the food, pharmaceutical, and cosmetic industries are summarized, and the future development trends of aroma yeasts are discussed to provide a theoretical basis for their application in the food fermentation industry.

Plasmon-Induced Radical-Radical Heterocoupling Boosts Photodriven Oxidative Esterification of Benzyl Alcohol over Nitrogen-Doped Carbon-Encapsulated Cobalt Nanoparticles.

Selective oxidation of alcohols under mild conditions remains a long-standing challenge in the bulk and fine chemical industry, which usually requires environmentally unfriendly oxidants and bases that are difficult to separate. Here, a plasmonic catalyst of nitrogen-doped carbon-encapsulated metallic Co nanoparticles (Co@NC) with an excellent catalytic activity towards selective oxidation of alcohols is demonstrated. With light as only energy input, the plasmonic Co@NC catalyst effectively operates via combining action of the localized surface-plasmon resonance (LSPR) and the photothermal effects to achieve a factor of 7.8 times improvement compared with the activity of thermocatalysis. A high turnover frequency (TOF) of 15.6 h-1 is obtained under base-free conditions, which surpasses all the reported catalytic performances of thermocatalytic analogues in the literature. Detailed characterization reveals that the d states of metallic Co gain the absorbed light energy, so the excitation of interband d-to-s transitions generates energetic electrons. LSPR-mediated charge injection to the Co@NC surface activates molecular oxygen and alcohol molecules adsorbed on its surface to generate the corresponding radical species (e.g., ⋅O2 - , CH3 O⋅ and R-⋅CH-OH). The formation of multi-type radical species creates a direct and forward pathway of oxidative esterification of benzyl alcohol to speed up the production of esters.

Plasmon‐Induced Radical‐Radical Heterocoupling Boosts Photodriven Oxidative Esterification of Benzyl Alcohol over Nitrogen‐Doped Carbon‐Encapsulated Cobalt Nanoparticles

AbstractSelective oxidation of alcohols under mild conditions remains a long‐standing challenge in the bulk and fine chemical industry, which usually requires environmentally unfriendly oxidants and bases that are difficult to separate. Here, a plasmonic catalyst of nitrogen‐doped carbon‐encapsulated metallic Co nanoparticles (Co@NC) with an excellent catalytic activity towards selective oxidation of alcohols is demonstrated. With light as only energy input, the plasmonic Co@NC catalyst effectively operates via combining action of the localized surface‐plasmon resonance (LSPR) and the photothermal effects to achieve a factor of 7.8 times improvement compared with the activity of thermocatalysis. A high turnover frequency (TOF) of 15.6 h−1 is obtained under base‐free conditions, which surpasses all the reported catalytic performances of thermocatalytic analogues in the literature. Detailed characterization reveals that the d states of metallic Co gain the absorbed light energy, so the excitation of interband d‐to‐s transitions generates energetic electrons. LSPR‐mediated charge injection to the Co@NC surface activates molecular oxygen and alcohol molecules adsorbed on its surface to generate the corresponding radical species (e.g., ⋅O2−, CH3O⋅ and R‐⋅CH‐OH). The formation of multi‐type radical species creates a direct and forward pathway of oxidative esterification of benzyl alcohol to speed up the production of esters.

Precise tuning of silica pore length and pore diameter on silica-encapsulated gold core–shell nanoparticles and catalytic impact

The ability to individually tune the pore length and pore diameter of silica-encapsulated gold core–shell nanoparticles (CSNPs) via a seeded encapsulation method is demonstrated and their impact on catalysis determined. Reducing the solvent volume during the shell growth phase resulted in CSNPs with shells of increasing thickness from 75 nm to 202 nm, following a linear relationship. The addition of 1, 3, 5-triisopropylbenzene (TIB) during synthesis increased the average pore diameter from 25 Å to 32 Å by swelling the pore template, swelling further to 38 Å when adding both TIB and n-decane. By decoupling the gold core reduction and silica condensation stages, gold core diameters were largely unaffected by silica growth reaction conditions. This was achieved by encapsulating CTAB-stabilized nanoparticles rather than reducing and stabilizing the nanoparticles during silica condensation. When used to catalyze solvent-free benzyl alcohol oxidation, it was found that CSNPs with increasing shell thicknesses demonstrated increased formation of the desirable aldehyde product, holding the undesired ester product yield constant. In contrast, CSNPs with increasing pore diameter exhibit increased formation of both aldehyde and ester products unselectively. These results—uniquely observed through the parametric isolation of pore length and diameter—suggest the reactant concentration at the pore wall due to hydrogen bonding, forming concentric “microphases” within the pores.

The ester production capacity of Pichia kudriavzevii based on functional annotation of genes.

Esters were identified as the primary volatile flavor compounds in Chinese Baijiu, exerting a significant influence on its quality and aroma. This study focused on the yeast strain Pichia kudriavzevii, renowned for its high capacity to produce esters. Whole genome sequences were annotated and analyzed using the GO, KEGG, KOG, CAZy, and Pfam databases to determine the genetic basis underly the enhanced ester production capacity. Results showed that P. kudriavzevii gene function was concentrated in biosynthetic capacity, metabolic capacity, amino acid translocation capacity, glycoside hydrolysis capacity and transfer capacity. Additionally, acyltransferase and kinase were predicted as active sites contributing to P. kudriavzevii high ester production. We further compared the volatile composition differences between P. kudriavzevii and Saccharomyces cerevisiae through Headspace solid-phase microextraction-gas Chromatography-mass spectrometry (HS-SPME-GC-MS), revealing P. kudriavzevii produced 3.5 times more esters than S. cerevisiae. Overall, our findings suggest that P. kudriavzevii had potential applications in the Baijiu brewing industry.

Techno-economic assessment of benzyl benzoate clean production using conventional heating or microwaves

Benzyl benzoate is an important anti-scabies agent, so finding sustainable production processes is essential. This work involved the techno-economic assessment of benzyl benzoate production in a solventless system with conventional heating or microwave-assisted. The proposed processes' conditions were optimized by transesterifying methyl benzoate and benzyl alcohol in a solventless system using the Lipozyme 435 lipase as the catalyst. The optimized conditions were an ester/alcohol molar ratio of 1:6, a temperature of 73 °C, and enzyme loading of 10% and 16% (w/w), for conventional heating and microwave-assisted, respectively. Under these conditions, the two reactions reached conversions greater than 90% in 24 h and 82% in 7 h. The tests on lipase reusability showed that the ester production remains stable for up to 4 use cycles. Gas chromatography and proton NMR confirmed that benzyl benzoate could be produced biocatalytically, and a high purity can be obtained by simple distillation. The economic analysis of the process showed that the total capital investment was favorable, suggesting a promising investment opportunity. Furthermore, a production total cost showed a favorable positive net present value and returned on investment for benzyl benzoate production. Hence, the proposed clean production of benzyl benzoate can be considered for industrial scale-up.

Carbon-Based Solid Acid Catalyzed Esterification of Soybean Saponin-Acidified Oil with Methanol Vapor for Biodiesel Synthesis

In this study, carbon-based solid acids were used to catalyze the esterification of soybean saponin-acidified oil (SSAO) with methanol vapor for the synthesis of biodiesel. The esterification conversion under different conditions was determined, and the catalyst components were determined using acid-base titration, elemental analysis, and inductively coupled plasma spectroscopy. The results showed that the conversion of SSAO under the optimal esterification conditions (i.e., catalyst loading of 6 wt%, methanol/oil molar ratio of 50:1, reaction temperature of 76 °C, and reaction time of 4 h) was 98.9%. The conversion was still higher than 80% after the catalyst was reused for four batches. The methanol vapor esterification (MVE) effectively mitigated the leaching of sulfonic acid groups and the production of sulfonate esters, while the activated white clay adsorption can significantly reduce the metal ion content in SSAO, which weakens its ion exchange with sulfonic acid groups. MVE for biodiesel synthesis is less costly compared to liquid methanol esterification because of the high recovery of methanol and the improved catalyst stability. Therefore, the addition of methanol in the form of vapor in the carbon-based solid acid-catalyzed esterification system is an effective way to maintain the catalyst activity and reduce the production cost of biodiesel.

Influence of Molecular Structure on the Physicochemical and Tribological Properties of Biolubricants: A Review

The increase in the price of crude oil, the environmental impact, or the depletion of fossil resources has increased the need for bio-based alternatives. This has led to the search for renewable, biodegradable, and environmentally friendly raw materials to obtain lubricants that meet these characteristics. This review deals with the state of the art of biolubricants along with their most common raw materials and molecular structures, processes of chemical modification of bio-oils, as well as the relationship between their structural features and physicochemical/tribological properties. This review concludes that the production of fatty acid alkyl esters from vegetable oils is the most promising chemical route to produce a wide range of biolubricants through double transesterification reactions. It also highlights the need to explore this route for the production of microalgae-derived biolubricants due to its environmental benefits during cultivation and production processes.

Towards carotenoid biofortification in wheat: identification of XAT-7A1, a multicopy tandem gene responsible for carotenoid esterification in durum wheat

Yellow pigment content, mainly due to the accumulation of carotenoids, is a quality trait in durum wheat grain as it confers the bright yellow color to pasta preferred by consumers. Also, carotenoids are essential nutrients exerting important biological functions in human health. Consequently, biofortification strategies have been developed in many crops to increase carotenoid content. In this context, carotenoid esterification is emerging as a new breeding target for wheat biofortification, as carotenoid esters have been found to promote both carotenoid accumulation and stability. Until recently, no carotenoid esters have been identified in significant proportions in durum wheat grains, and interspecific breeding programs have been started to transfer esterification ability from common wheat and Hordeum chilense.In this work, XAT-7A1 is identified as the gene responsible for carotenoid esterification in durum wheat. Sequencing, copy number variation and mapping results show that XAT-7A1 is organized as tandem or proximal GDSL esterase/lipase copies in chromosome 7A. Three XAT-7A1 haplotypes are described: Type 1 copies, associated with high levels of carotenoid esters (diesters and monoesters) production and high expression in grain development; Type 2 copies, present in landraces with low levels of carotenoid esters (monoesters) or no esters; and Type 3 copies, without the signal peptide, resulting in zero-ester phenotypes.The identification of XAT-7A1 is a necessary step to make the carotenoid esterification ability available for durum and bread wheat breeding, which should be focused on the Type 1 XAT-7A1 haplotype, which may be assessed as a single gene since XAT-7A1 copies are inherited together.

Biocatalysts Based on Immobilized Lipases for the Production of Ethyl Esters of Fatty Acids including Bioactive Gamma-Linolenic Acid from Borage Oil

In the present work, borage oil (Borago officinalis) was used as the main source of gamma linolenic acid (GLA) to obtain ethyl esters by enzymatic ethanolysis using immobilized enzymes for its application in the food industry. Commercial Thermomyces lanuginosus lipase (TLL) was compared to chemical ethanolysis in alkaline medium. In addition, TLL was immobilized by adsorption on hydrophobic porous support (Octadecyl-Sepabeads®) to compare the results. Fatty acid ethyl ester (FAEE) yields of both reactions were compared under the same conditions (25 °C and 200 rpm) and analyzed by GC-MS. Moreover, the conversion yield for borage oil ethanolysis catalyzed by TLL immobilized on C18-Sepabeads® supports was similar to the chemical pathway (93.4% and 99.5%, respectively). When this biocatalyst was used in a solvent-free system (at 40 °C and 200 rpm), it was possible to obtain a high FAEE yield of 84.3% in the first 24 h of reaction. Furthermore, it was possible to re-use the immobilized biocatalyst for the performance of five reaction cycles maintaining 68% of its initial activity. Thus, the use of immobilized enzymes in solvent-free systems is an eco-friendly alternative to obtain GLA ethyl esters for its possible application in cosmetics and food.

INCREASING THE LUBRICANT RESOURCE BY DEVELOPING A DEVICE FOR ITS CLEANING

Agricultural production is one of the main consumers of oil products. The enterprises of the agro-industrial complex of Ukraine annually consume about 7 million tons of produced diesel fuel and about 1.0 million tons of motor oil. An average farm in the central zone consumes up to 1,200 tons of diesel fuel, 600 tons of gasoline, and 60 tons of curtain oils per year, of which at least 80% goes into the category of spent petroleum products of various groups. As a result of the intensive growth of the fleet of internal combustion engines, as well as increased attention to economic and environmental factors, the task of saving and rational use of fuel and energy, raw materials and other material resources is becoming increasingly acute for the national economy. It is known that one of the ways to increase the level of supply of agricultural production with motor oils is their repeated use after the restoration of some quality indicators that have deteriorated as a result of their use in the operation of auto-tractor equipment. The repeated use of oils allows you to increase their service life, reduce irreversible losses and reduce the shortage of oil supplies to farms. However, the rate of use of recovered oils remains at a low level. Thus, in the country as a whole, the annual discharge of used oils amounted to 0.9 million tons, and only 0.15 million tons were regenerated, which is about 16% of the collected volume. The proposed device can be used within the framework of the initiative topic "Investigation of ways to optimize the parameters of the technological process for the production of fatty acid esters for diesel biofuel" (state registration number: 0122U002187 dated 30.03.2022), and investigated under the initiative topic: "Investigation of the influence of the bioethanol component of the fuel mixture on the parameters operation of a gasoline injection engine" (state registration number: 0122U00213 dated 30.03.2022).

Kinetic modeling of bio-based heterogeneously catalyzed lard oil methanolysis in methyl ester production

Kinetic modeling of bio-based heterogeneously catalyzed lard oil methanolysis in methyl ester production

Automated production of 11C-labeled carboxylic acids and esters via "in-loop" 11C-carbonylation using GE FX synthesis modules.

An in-loop 11C-carbonylation process for the radiosynthesis of 11C-carboxylic acids and esters from halide precursors has been developed. The reaction proceeds at room temperature under mild conditions and enables 11C-carbonylation of both electron deficient and electron rich (hetero)aromatic halides to provide 11C-carboxylic acids and esters in good to excellent radiochemical yields, high radiochemical purity, and excellent molar activity. The process has been fully automated using commercial radiochemistry synthesis modules, and application to clinical production is demonstrated via validated cGMP radiosyntheses of [11C]bexarotene and [11C]acetoacetic acid.

Developing fluorescence-improved fluoran dyes and applying for a copper selective and sensitive fluorescent probe and cell imaging

Developing fluoran dyes for fluorescent material is significant but challenging because they are notorious for terrible luminescent efficiency. In this manuscript, two fluoran dyes (F3 and F4) were synthesized by the introduction of thiazole and indazole into the fluoran skeleton, which showed colored and fluorescent spirolactone opening form in a wide pH range (F3: 1–10, F4: 1–13). In addition, the absorption and emission spectra of methyl esterification products F3Me and F4Me showed large Stokes shifts (over 75 nm) in water and achieved an improved fluorescence quantum yield of 30.1% in CHCl3. Based on the dye F4Me, a new fluorescent probe F4HP was developed, which showed high selectivity and high sensitivity (LOD of 2.0 nM) to copper ions in H2O/CH3CN (v/v, 3/2) system. Moreover, the sensing experiment was allowed in the pH range of 4.0–7.5. Furthermore, the F4HP exhibits suitable cell cytotoxicity and can be applied for imaging intracellular copper ions by confocal fluorescence imaging technology.

Upgrading catalytic properties of green synthesized TiO2 for green fuel production from apricot seeds oil

The ongoing energy crisis and global warming issues have pushed the research community to search for sustainable energy supplies such as biodiesel (methyl esters). In this regard, inedible oils which are not consumed by humans could be potential sources for methyl esters production. Herein, the methyl esters were produced by trans-esterifying the apricot seeds oil (ASO) employing series of green synthesized (mediated by banana peel extract) TiO2 based NiO-TiO2 heterogeneous nano-catalysts with varying loadings of NiO (5, 10 and 15 by wt%). The as-prepared catalysts were characterized using advanced techniques like FT-IR, XRD, SEM and FE-SEM. These studies established the successful impregnation of NiO with TiO2 NPs. The efficiency of NiO-TiO2 with 10 wt% of NiO loading calcined at 500 °C was superior due to the highest biodiesel yield compared to other nano-catalysts. The parametric study of transesterification reaction to yield methyl esters adapting this catalyst revealed the maximum yield (93.4 %) with MeOH: oil and catalyst loading of 20:1 and 2 wt% correspondingly in 1 h at 55 °C. GC–MS analysis was executed for investigating and confirming the composition of obtained methyl esters at optimized conditions. Furthermore, the heterogeneous catalyst was reusable for five cycles for transesterification of ASO. The kinetic investigations showed that transesterification of ASO was compatible with pseudo-first order model. In addition, fuel characteristics such as calorific and acid value were measured by using titrations and bomb calorimeter respectively and compared with ASTM6751 and EN14214 standards.

Methyl Esters Production from Degummed Soybean Oil Catalyzed by Niobium Phosphate

Methyl Esters Production from Degummed Soybean Oil Catalyzed by Niobium Phosphate