Hydrolysis Of Glycerides Research Articles

Comprehensive lipid hydrolysis observation in anaerobic digestion

Lipid hydrolysis monitoring, including especially glycerides, is necessary for comprehending the anaerobic digestion process in lipid-rich substrates processing. This reaction has not been investigated in such detail so far, despite its potential to be crucial in assuring a stable process. This study suggested and thoroughly validated an uncomplicated method of monitoring lipid hydrolysis during anaerobic digestion, achieving recovery values >95 % with an average relative standard deviation <5 %. Subsequently, the method was applied on the very first detailed observation of glyceride hydrolysis in the anaerobic sludge, tracking even changes in fatty acid profiles during anaerobic digestion. Results showed that lipid hydrolysis can take several days, thus likely affecting the whole anaerobic digestion of lipids. The method aims to provide answers to improve understanding of lipids' fate and their inhibition phenomena in anaerobic digestion.

Relationship between PAH4 formation and thermal reaction products in model lipids and possible pathways of PAHs formation

Lipids are closely related to the generation of PAHs during food thermal processing. During heating, lipids mainly triglycerides undergo hydrolysis, oxidation and decomposition. The relationship between the various products and the formation of PAHs is still unclear. This paper investigated the effect of different lipid standards on PAH4 production, and explored their thermal stability and reaction products to delve into nature of the differences in PAH4 production. Fatty acids were more prone to generate PAH4 than glycerides. The higher the degree of esterification of glycerides, the higher its thermal stability and the lower the content of PAH4 generated, implying that hydrolysis of glycerides promoted the generation of PAH4. In addition, there was a positive correlation between unsaturation in lipids and the PAH4 production. After heat treatment, hydroperoxides, unsaturated fatty alcohols and aldehydes, alkenes and aromatic substances were abundant in oleic acid and linoleic acid which produced the most PAH4. Thermal decomposition of lipid hydroperoxides was the pathway for the generation of conjugated hydrocarbon radicals, alcohols, aldehydes, and alkenes. The intramolecular cyclization and Diels-Alder reaction acted as ring-forming reactions, with consequent dehydrogenation, decarboxylation, side-chain breaks and radical reorganization, ultimately facilitating the amplification of the aromatic rings and the formation of PAHs.

Cooperation of acylglycerol hydrolases in neuronal lipolysis

Genetic and biochemical evidence has established DDHD-domain containing 2 (DDHD2) as the principal triacylglycerol (TAG) hydrolase in neuronal lipolysis of cytosolic lipid droplets. In this issue of Journal of Lipid Research, Hofer et al. report that DDHD2 cooperates with adipose triglyceride lipase, the principal TAG hydrolase in adipose lipolysis, contributing to cytosolic hydrolysis of both TAG and diacylglycerols in murine neuroblastoma cells and primary cortical neurons via different configurations of the lipases. This finding highlights the complexity of cytosolic acylglycerol hydrolysis and raises many new questions in the field of lipid metabolism.

Lipidomic analysis and classification of Iberian dry‐cured hams with low field NMR

AbstractIberian ham is a high‐quality food that is traditionally produced from black pigs that are native to the Iberian Peninsula. The taste and texture of Iberian ham are largely determined by its lipid content and composition. In this work, low field 1H‐NMR spectroscopy was used for the first time to analyze the lipid profile of Iberian hams as a determinant of quality. The quantification of fatty acids (FAs) is readily obtained from the integration of the spectral peaks. The FA profile is highly influenced by the diet of the pigs, with monounsaturated FAs being more prominent in hams from acorn‐fed pigs. The NMR data was analyzed using a sparse partial least squares multivariate data analysis multivariate model, which allowed for the categorization of Iberian hams according to the pig's feeding regime. The main variables on which this classification is based are FA unsaturation and triacyl glyceride hydrolysis. On the other hand, there are no significant differences in the phospholipid content of the different categories of Iberian hams as determined by colorimetric and inductively coupled plasma optical emission spectroscopy methods.Benchtop 1H‐NMR spectroscopy has thus revealed as an operationally simple and powerful tool for the lipid analysis and classification of Iberian hams according to the diet of pigs.

Preparation of 2-Arachidonoylglycerol by Enzymatic Alcoholysis: Effects of Solvent and Water Activity on Acyl Migration

Enzymatic alcoholysis was performed in an organic medium to synthesize 2-monoacylglycerol (2-MAG) rich in arachidonic acid. The results showed that solvent type and water activity (aw) significantly affected the 2-MAG yield. Under the optimum conditions, 33.58% 2-MAG was produced in the crude product in t-butanol system. Highly pure 2-MAG was obtained after two-stage extraction using 85% ethanol aqueous solution and hexane at first stage and dichloromethane and water at second stage. Isolated 2-MAG was used as substrate to investigate the effect of solvent type and aw on 2-MAG acyl migration in a lipase-inactivated system. The results indicated that non-polar solvents accelerated the acyl migration of 2-MAG, whereas isomerization was inhibited in polar solvent systems. The aw exhibited the strongest inhibition effect on 2-MAG isomerization at 0.97, but also affected the hydrolysis of glycerides and lipase selectivity.

Esterification of enzymatically treated macaw palm oil catalyzed by heteropolyacid supported onto Nb2O5

An approach to producing biodiesel is the esterification of free fatty acids with an acyl acceptor. Free fatty acids can be produced through the hydrolysis of acylglycerols and represent a somewhat challenging feedstock for the production of biodiesel due to slower kinetics and the production of water in the reaction. The purpose of this work was to demonstrate the feasibility of a Keggin-structured heteropolyacid, H3PW12O40 (HPW) supported onto Nb2O5 to be used as a catalyst for the reaction of free fatty acids with ethanol to produce ethyl esters that comply with biodiesel norm values. The use of heteropolyacids as heterogeneous catalysts may present advantageous operational benefits, including the tolerance to residual water present in the medium and the potential for reusability. The catalyst was prepared via impregnation of HPW onto Nb2O5 and was characterized in terms of acidity and surface properties. The enzymatic hydrolysis of macaw palm oil yielded a feedstock containing a free fatty acid content greater than 93%. The hydrolysate was assessed as a reactant for the esterification reaction, evaluating temperature, molar ratio, and catalyst amount, leading to optimal conversions greater than 99% with viscosity and density within the regulatory limits for biodiesel. The use of heterogeneous acid catalysts, such as HPW/Nb2O5, represents a potentially feasible alternative to unlocking the potential of working with challenging feedstocks as oil hydrolysates.

PH-dependent warping behaviors of ancient lacquer films excavated in Shanxi, China

The ancient lacquer films excavated from Dongshan Han tomb M6 of the Western Han Dynasty in Taiyuan City, Shanxi, China, were found sensitive to pH variation. This paper aims to demonstrate the pH-dependent warping behaviors of the ancient lacquer film and discuss their mechanism. The samples were analyzed by surface analytical techniques including attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry. The results suggest that the outer layer of the lacquer film is more oxidized than the inner layer and contains more carboxylates, with calcium ions and possibly ammonium cations as counter ions. The carboxylates are speculated to be formed by oxidative cleavages in the urushiol side chains and hydrolysis of glycerides of drying oils. The shrinkage and swelling of the lacquer film can be regulated by the type of cations (H+, Ca2+, Na+) of carboxylates through hydrogen bonds, coordination bonds and static forces. Due to the higher content of carboxylates in the outer part, it shrinks more at low pH causing warping outward and swells more at high pH causing warping inward. This paper may provide an important reference for pH control and help resolve the warping problem during conservation or restoration of ancient lacquerware.

Performance of Liquid Eversa on Fatty Acid Ethyl Esters Production by Simultaneous Esterification/Transesterification of Low-to-High Acidity Feedstocks

Liquid Eversa was evaluated in hydrolysis of acylglycerols from soybean oil deodorizer distillate (SODD), as well as simultaneous esterification/transesterification of SODD with low-to-high free fatty acids (FFAs) content using ethanol as acyl acceptor. Hydrolysis of SODD at mild temperature (37 °C) and without pH control (water:SODD mass ratio of 4:1) increased its FFAs content from 17.2 wt.% to 72.5 wt.% after 48 h reaction. A cold saponification of SODD allowed a saponification phase (SODD-SP) to be recovered with 93 wt.% saponification index and 2.25 wt.% FFAs content, which was used to find the experimental conditions for simultaneous esterification/transesterification reactions by experimental design. Temperature of 35 °C, enzyme concentration of 8.36 wt.%, and molar ratio of 3.64:1 (ethanol:SODD-SP) were found as the best conditions for fatty acid ethyl esters (FAEEs) production from SODD-SP (86.56 wt.% ester yield after 23 h reaction). Under the same reaction conditions, crude SODD (17.2 wt.% FFAs) and hydrolyzed SODD (72.5 wt.% FFAs) yielded products containing around 80 wt.% FAEEs. Caustic treatment could increase the ester content to around 90 wt.% and reduce the FFAs content to less than 1 wt.%. Our results show the good performance of liquid Eversa in aqueous (hydrolysis reactions) and organic (esterification/transesterification reactions) media.

Tissue distribution of transcription for 29 lipid metabolism-related genes in Takifugu rubripes, a marine teleost storing lipid predominantly in liver.

The tissue distribution pattern of lipid is highly diverse among different fish species. Tiger puffer has a special lipid storage pattern, storing lipid predominantly in liver. In order to better understand the lipid physiology in fish storing lipid in liver, the present study preliminarily investigated the tissue distribution of transcription for 29 lipid metabolism-related genes in tiger puffer, which are involved in lipogenesis, fatty acid oxidation, biosynthesis and hydrolysis of glycerides, lipid transport, and relevant transcription regulation. Samples of eight tissues, brain, eye, heart, spleen, liver, intestine, skin, and muscle, from fifteen juvenile tiger puffer were used in the qRT-PCR analysis. The intestine and brain had high transcription of lipogenic genes, whereas the liver and muscle had low expression levels. The intestine also had the highest transcription level of most apolipoproteins and lipid metabolism-related transcription factors. The transcription of fatty acid β-oxidation-related genes was low in the muscle. The peroxisomal fatty acid oxidation may dominate over mitochondrial β-oxidation in the liver and intestine of tiger puffer, and the MAG pathway probably predominates over the G3P pathway in re-acylation of absorbed lipids in the intestine. The intracellular glyceridases were highly transcribed in the brain, eye, and heart. In conclusion, in tiger puffer, the intestine could be a center of lipid metabolism whereas the liver is more likely a pure storage organ for lipid. The lipid metabolism in the muscle could also be inactive, possibly due to the very low level of intramuscular lipid.

Characterization of biodiesel from frying oil obtained by hydro-esterification using vermiculite as heterogeneous catalyst

This study aimed to understand the synthesis of biodiesel from the residual frying oil through the hydro-esterification reaction using vermiculite as heterogeneous catalytic. The hydrolysis was carried out in an autoclave reactor at a temperature of 300 °C for 3 h. Then, the esterification was performed under the molar ratio of 6:1 of ethyl alcohol/fatty acid, in the presence of 5% of the catalyst concerning the oil mass. We analyzed the physicochemical and thermal characteristics of both the biodiesel and the frying oil, and the spectrophotometric parameters of absorption in the UV–visible region. We found a reaction yield relative to the mass of the residual frying oil of 66.65%. The thermogravimetric curve for biodiesel showed two stages of decomposition: the first stage with 83.1% of mass loss, indicating conversion to monoacylglycerols, and the second with 14.3% of mass loss, attributed to the presence of traces of diacylglycerides and triacylglycerides not converted into esters of ethyl fatty acids. The absorption spectra in the infrared region confirmed the presence of ethyl fatty acid esters at 1749.7 cm−1 but also verified the presence of a vibrational band corresponding to the OH group stretching at 3600 to 3300 cm−1, confirming the presence of moisture or the partial conversion of the glyceride hydrolysis. Finally, the results show a satisfactory conversion, although more detailed studies are still required.

Wide target analysis of acylglycerols in miso (Japanese fermented soybean paste) by supercritical fluid chromatography coupled with triple quadrupole mass spectrometry and the analysis of the correlation between taste and both acylglycerols and free fatty acids.

The acylglycerols in miso have not been studied although it is known that they are important to the taste. In order to determine the fatty acid constituents in the acylglycerols and analyze them individually, multiple reaction monitoring (MRM) was performed utilizing a single platform, typically using both gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry. Acylglycerols and fatty acids (FAs) in miso were extracted using the Bligh-Dyer method. Supercritical fluid chromatography (SFC) with a C30 column was conducted for separation, and mass spectrometric (MS) analysis was performed with electrospray ionization using a triple quadrupole mass spectrometer (QqQMS) in the MRM mode. The detection of FAs from the hydrolysis of acylglycerols and individual acylglycerols was achieved using only an SFC/MS platform. From the quality control (QC) sample of miso, we determined the main FA constituents, and then performed wide target analysis using MRM. In total, 23 triacylglycerols, 10 diacylglycerols, two monoacylglycerols, and five FAs were annotated effectively. Furthermore, the important compounds related to taste were determined through the analysis using both the relative quantitative data of acylglycerols and FAs and the quantitative descriptive analysis data of miso. A method for the determination of the FA constituents in acylglycerols after hydrolysis and the comprehensive analysis of acylglycerols and FAs using MRM with SFC/QqQMS was developed. Using the data from the comprehensive analysis of acylglycerols and quantitative descriptive data, the key compounds related to taste were investigated. This type of research on lipids and the taste of food is expected to progress hereafter. Copyright © 2017 John Wiley & Sons, Ltd.

Revealing the Nature and Distribution of Metal Carboxylates in Jackson Pollock's Alchemy (1947) by Micro-Attenuated Total Reflection FT-IR Spectroscopic Imaging.

Protrusions, efflorescence, delamination, and opacity decreasing are severe degradation phenomena affecting oil paints with zinc oxide, one of the most common white pigments of the 20th century. Responsible for these dramatic alterations are the Zn carboxylates (also known as Zn soaps) originated by the interaction of the pigment and the fatty acids resulting from the hydrolysis of glycerides in the oil binding medium. Despite their widespread occurrence in paintings and the growing interest of the scientific community, the process of formation and evolution of Zn soaps is not yet fully understood. In this study micro-attenuated total reflection (ATR)-FT-IR spectroscopic imaging was required for the investigation at the microscale level of the nature and distribution of Zn soaps in the painting Alchemy by J. Pollock (1947, Peggy Guggenheim Collection, Venice) and for comparison with artificially aged model samples. For both actual samples and models, the role of AlSt(OH)2, a jellifying agent commonly added in 20th century paint tube formulations, proved decisive for the formation of zinc stearate-like (ZnSt2) soaps. It was observed that ZnSt2-like soaps first form around the added AlSt(OH)2 particles and then eventually grow within the whole painting stratigraphy as irregularly shaped particles. In some of the Alchemy samples, and diversely from the models, a peculiar distribution of ZnSt2 aggregates arranged as rounded and larger particles was also documented. Notably, in one of these samples, larger agglomerates of ZnSt2 expanding toward the support of the painting were observed and interpreted as the early stage of the formation of internal protrusions. Micro-ATR-FT-IR spectroscopic imaging, thanks to a very high chemical specificity combined with high spatial resolution, was proved to give valuable information for assessing the conservation state of irreplaceable 20th century oil paintings, revealing the chemical distribution of Zn soaps within the paint stratigraphy before their effect becomes disruptive.

Lipase‐Catalyzed Production of Biodiesel by Hydrolysis of Waste Cooking Oil Followed by Esterification of Free Fatty Acids

AbstractBiodiesel is conventionally produced by alkaline‐catalyzed transesterification, which requires high‐purity oils. However, low‐quality oils can be used as feedstocks for the production of biodiesel by enzyme‐catalyzed reactions. The use of enzymes has several advantages, such as the absence of saponification side reactions, production of high‐purity glycerol co‐product, and low‐cost downstream processing. In this work, biodiesel was produced from lipase‐catalyzed hydrolysis of waste cooking oil (WCO) followed by esterification of the hydrolyzed WCO (HWCO). The hydrolysis of acylglycerols was carried out at 30 °C in salt‐free water (WCO/water ratio of 1:4, v/v) and the esterification of HWCO was carried out at 40 °C with ethanol in a solvent‐free medium (HWCO/ethanol molar ratio of 1:7). The hydrolysis and esterification steps were carried out using immobilized Thermomyces lanuginosus lipase (TLL/WCO ratio of 1:5.6, w/w) and immobilized Candida antarctica lipase B (10 wt%, CALB/HWCO) as biocatalysts, respectively. The hydrolysis of acylglycerols was almost complete after 12 h (ca. 94 %), and in the esterification step, the conversion was around 90 % after 6 h. The purified biodiesel had 91.8 wt% of fatty acid ethyl esters, 0.53 wt% of acylglycerols, 0.003 wt% of free glycerol, viscosity of 4.59 cP, and acid value of 10.88 mg KOH/g. Reuse hydrolysis and esterification assays showed that the immobilized enzymes could be recycled five times in 10‐h batches, under the conditions described above. TLL was greatly inactivated under the assay conditions, whereas CALB remained fully active. The results showed that WCO is a promising feedstock for use in the production of biodiesel.

Lipase-catalysed transesterification: Viewpoint of the mechanism and influence of free fatty acids

A series of lipase-catalysed transesterification experiments were carried out to study the effect of the presence of free fatty acids on synthesis reaction rate and the stability of the biocatalyst, and also to elucidate the underlying process, which remains a subject of debate. Based on the results, the reaction rate and biocatalyst stability increased with increasing content in free fatty acids of the reaction mixture. Also, tests carried out with a mixture of triolein and linoleic acid revealed that the transesterification is a combination of direct alcoholysis of triacylglycerols and a two-step reaction involving hydrolysis of acylglycerols and further esterification of previously released free fatty acids. The time course of triacylglycerols and diacylglycerols revealed that the enzyme is similarly selective for both types of substrate.

Kinetic study on lipase-catalyzed biodiesel production from waste cooking oil

A kinetic model of the biodiesel production from waste cooking oil using Candida sp. 99-125 lipase as catalyst was established in this paper. The limited reaction steps in the model were considered to be the hydrolysis of glycerides and the esterification of free fatty acids, while the methanolysis of glycerides were considered to be negligible. Matlab programming platform was used to estimate the parameters of the model. A series of experiments were conducted to verify the validity of the model. The results showed that the model could adequately simulate the reaction results of biodiesel production at different lipase loadings, substrate ratios and initial water concentrations. The agreement between experimental data and calculated values was good, which could prove the validity of the kinetic model. Moreover, the results of biodiesel production using a twelve-step methanol feeding method and a three-step methanol feeding method could be simulated well by the kinetic model. The results indicated that the model could also simulate the biodiesel production using methanol step-wise addition.

Changes in polar and non-polar lipid fractions of subcutaneous fat from Iberian ham during dry-curing process. Prediction of the curing time

The aim of this study was to investigate the changes in polar and non-polar lipid fractions from subcutaneous adipose tissue during the ripening of Iberian dry-cured hams. Total fatty acid, triacylglycerol and phospholipid amounts decreased with processing whereas diacylglycerol, monoacylglycerol and free fatty acid amounts grew up. Phospholipids were only detected during postsalting period, decreasing markedly with an exponential trend. In this kind of fat, the free fatty acids do not come mostly from phospholipid hydrolysis as occurs in intramuscular fat. Drying period is characterized by an intense lipolysis of triacylglycerols and diacylglycerols. The hydrolysis would be more influenced by enzymes and microorganism action in the two first periods while cellar would be characterized by chemical hydrolysis of acylglycerols, oxidation of these and fatty acids and sweat of fat. Pattern recognition techniques combined with mathematical analysis of fatty acids and diacylglycerols have been used in order to predict the curing time.

Cholesteryl ester accumulation and accelerated cholesterol absorption in intestine-specific hormone sensitive lipase-null mice

Hormone sensitive lipase (HSL) regulates the hydrolysis of acylglycerols and cholesteryl esters (CE) in various cells and organs, including enterocytes of the small intestine. The physiological role of this enzyme in enterocytes, however, stayed elusive. In the present study we generated mice lacking HSL exclusively in the small intestine (HSLiKO) to investigate the impact of HSL deficiency on intestinal lipid metabolism and the consequences on whole body lipid homeostasis. Chow diet-fed HSLiKO mice showed unchanged plasma lipid concentrations. In addition, feeding with high fat/high cholesterol (HF/HC) diet led to unaltered triglyceride but increased plasma cholesterol concentrations and CE accumulation in the small intestine. The same effect was observed after an acute cholesterol load. Gavaging of radioactively labeled cholesterol resulted in increased abundance of radioactivity in plasma, liver and small intestine of HSLiKO mice 4h post-gavaging. However, cholesterol absorption determined by the fecal dual-isotope ratio method revealed no significant difference, suggesting that HSLiKO mice take up the same amount of cholesterol but in an accelerated manner. mRNA expression levels of genes involved in intestinal cholesterol transport and esterification were unchanged but we observed downregulation of HMG-CoA reductase and synthase and consequently less intestinal cholesterol biosynthesis. Taken together our study demonstrates that the lack of intestinal HSL leads to CE accumulation in the small intestine, accelerated cholesterol absorption and decreased cholesterol biosynthesis, indicating that HSL plays an important role in intestinal cholesterol homeostasis.

Tackling myocardial metabolism: One year evaluation of free fatty acids, norephinephrine and NT-proBNP in ventricular fibrillation during STEMI

Sudden cardiac death (SCD) accounts for almost half of all deaths from cardiovascular causes in the Western World [1,2]. SCD is considered to be a consequence of malignant ventricular arrhythmias [3]. Primary ventricular fibrillation (VF) most commonly develops under circumstances of acute myocardial infarction in 80% of the cases [4,5]. During an acute episode of myocardial ischemia the myocardium needs optimal supply of nutrition and oxygenated blood to survive. The acute sympathomimetic catecholamine response triggered by norepinephrine (NE) after onset of chest-pain or breathlessness abruptly leads to hydrolysis of glycerides and free fatty acids (FFA or non-esterified fatty acids) [6,7].

Biodiesel Production from Vegetable Oils and Animal Fat over Solid Acid Double-Metal Cyanide Catalysts

Biodiesel comprises of fatty acid alkyl esters prepared from vegetable oils or animal fat by esterification/transesterification with short-chain alcohols (methanol or ethanol, for example). It is a biodegradable renewable fuel. Its production is growing exponentially due to greater concerns about environmental protection and depletion of fossil fuel resources. Further, its production from non-edible oils and animal fat is more desirable than from edible oils due to lower cost of non-edible feedstocks and elimination of food verses fuel issues. Solid acid catalysts are ideal for conversion of such low-grade oils to biodiesel. Biodiesel from non-edible oils can be produced by two methods: (1) simultaneous esterification of fatty acids and transesterification of fatty acid glycerides and (2) hydrolysis of glycerides followed by esterification. This account reports the catalytic performance of solid, Fe–Zn double-metal cyanide (DMC) complexes and other acid catalysts in these transformations for biodiesel production. The factors influencing the catalytic performance of the solid acid catalysts in biodiesel production are discussed.

Lipase from Rhizomucor miehei as a biocatalyst in fats and oils modification

The lipase from Rhizomucor miehei (RML), formerly Mucor miehei, is a commercially available enzyme in both soluble and immobilized forms with very high activity and good stability under diverse experimental conditions (anhydrous organic solvents, supercritical fluids, etc.). The uses of the enzyme were initially oriented towards food industry, that way the enzyme has found a broad application in this area. This review intends to show the enzyme features and some of the most relevant aspects of the use of this interesting enzyme in oils and fats modification. The enzyme has been the first lipase whose structure was reported and its interfacial activation is very well known, making this enzyme a good template for modeling studies. Finally, the main uses of the enzyme in fatty acids, oils and fats modification will be revised (hydrolysis of glycerides, transesterification, esterification, acidolysis and interesterification). This lipase seems to be advantageous when compared to other lipases mainly in esterificaton reactions in anhydrous media, while other lipases can be preferred in transesterification reactions.