Triacylglycerol Formation Research Articles

Effect of Single and Combined Expression of Lysophosphatidic Acid Acyltransferase, Glycerol-3-Phosphate Acyltransferase, and Diacylglycerol Acyltransferase on Lipid Accumulation and Composition in Neochloris oleoabundans.

Microalgal lipids are promising feedstocks for food and biofuels. Since lipid production by microalgae is not yet economically feasible, genetic engineering is becoming a promising strategy to achieve higher lipid accumulation and productivities. Enzymes involved in the Kennedy pathway such as glycerol-3-phosphate acyltransferase (GPAT), lysophosphatidic acid acyltransferase (LPAT), and diacylglycerol acyltransferase (DGAT) catalyze key steps in the formation of triacylglycerol, which is the main constituent of lipids in N. oleoabundans. The overexpression of these enzymes in the targeted strain has a great potential to further increase their triacylglycerol content. We overexpressed single and multiple encoding genes for LPAT, GPAT, and DGAT from Acutodesmus obliquus in N. oleoabundans. Strains overexpressing single genes produced up to 52% and 45% g · gDW-1, which corresponds to 1.3- and 1.4-fold increase in total fatty acids and triacylglycerols, respectively. The orchestrated expression of the three genes resulted in 49% and 39% g · gDW-1, which is 1.2-folds increase in total fatty acids and triacylglycerols. Single expression of LPAT, GPAT, and DGAT genes resulted in higher lipid productivities during starvation without a significant effect on growth and photosynthetic activity during replete conditions. On the other hand, the simultaneous expression of LPAT, GPAT, and DGAT genes resulted in 52% lower growth rate, 14% lower photosynthetic activity and 4-folds increase in cell diameter. Moreover, the multigene expressing line showed a decrease in carbohydrates and protein content and an increase in pigments during nitrogen starved condition. The single and multiple expression of heterologous genes LPAT, GPAT, and DGAT showed to significantly enhanced the lipid accumulation in N. oleoabundans. Single gene expression resulted in higher lipid production and productivities without having a significant impact in the physiological status of the strains. This approach shows the potential for the generation of microalgal strains with higher economical potential for the production of lipids.

Effect of Chemical Structure of Solid Lipid Matrix on Its Melting Behavior and Volumetric Expansion in Pressurized Carbon Dioxide

AbstractSupercritical carbon dioxide (SC‐CO2) technology offers new opportunities for green processing of lipids; however, there is little information of the melting behavior and volumetric expansion of solid lipids in pressurized CO2. In this study, melting behavior and volumetric expansion of two different solid lipid classes and the effect of the structural differences within the same lipid class on the melting behavior in pressurized CO2 were investigated. The melting point of the solid lipids decreased linearly with increasing pressures up to a certain level; then, it stayed constant. The highest melting point depression was observed for soybean oil monoacylglycerol (SO‐MAG) at 51.5 °C/110 bar, whereas the lowest was for fully hydrogenated soybean oil (FHSO) containing 30% SO‐MAG at 55.0 °C/79 bar. Melting point depression depended on lipid class. SO‐MAG exhibited a higher melting point depression than FHSO (triacylglycerol form), and its blends with SO‐MAG. There was no difference in melting point depression between glyceryl 1,2‐distearate and glyceryl 1,3‐distearate up to 200 bar (P > 0.05). A positive correlation between the melting point depression and volumetric expansion of solid lipids was observed. The highest volumetric expansion was for SO‐MAG in the linear region of the melting point depression curve, achieving 14.4% expansion compared to 9.3% for FHSO (P < 0.05). The highest dT/dP value (0.17 °C bar−1) was obtained for SO‐MAG, whereas the FHSO (0.09 °C bar−1) had the lowest one. Findings of this study will help optimize solid lipid‐involving SC‐CO2 processes for better protection of heat‐sensitive compounds while improving energy efficiency.

Effective editing for lysophosphatidic acid acyltransferase 2/5 in allotetraploid rapeseed (Brassica napus L.) using CRISPR-Cas9 system

BackgroundBrassica napus is one of the most important oilseed crops, and can supply considerable amounts of edible oil as well as provide raw materials for the production of biodiesel in the biotechnology industry. Lysophosphatidic acid acyltransferase (LPAT), a key enzyme in the Kennedy pathway, catalyses fatty acid chains into 3-phosphoglycerate and promotes further production of oil in the form of triacylglycerol. However, because B. napus is an allotetraploid with two subgenomes, the precise genes which involved in oil production remain unclear due to the intractability of efficiently knocking out all copies with high genetic redundancy. Therefore, a robust gene editing technology is necessary for gene function analysis.ResultsAn efficient gene editing technology was developed for the allotetraploid plant B. napus using the CRISPR-Cas9 system. Previous studies showed poor results in either on-target or off-target activity in B. napus. In the present study, four single-gRNAs and two multi-gRNAs were deliberately designed from the conserved coding regions of BnLPAT2 which has seven homologous genes, and BnLPAT5, which has four homologous genes. The mutation frequency was found to range from 17 to 68%, while no mutation was observed in the putative off-target sites. The seeds of the Bnlpat2/Bnlpat5 mutant were wizened and showed enlarged oil bodies, disrupted distribution of protein bodies and increased accumulation of starch in mature seeds. The oil content decreased, with an average decrease of 32% for Bnlpat2 lines and 29% for Bnlpat5 lines in single-gRNA knockout lines, and a decline of 24% for Bnlpat2 mutant lines (i.e., g123) and 39% for Bnlpat2/Bnlpat5 double mutant lines (i.e., g134) in multi-gRNA knockout lines.ConclusionsSeven BnLPAT2 homologous genes and four BnLPAT5 homologous genes were cleaved completely using the CRISPR-Cas9 system, which indicated that it is effective for editing all homologous genes in allotetraploid rapeseed, despite the relatively low sequence identities of both gene families. The size of the oil bodies increased significantly while the oil content decreased, confirming that BnLPAT2 and BnLPAT5 play a role in oil biosynthesis. The present study lays a foundation for further oil production improvement in oilseed crop species.

Potential of neutron powder diffraction for the study of solid triacylglycerols

Abstract We present a high-resolution neutron powder diffraction study of the triclinic β form of tripalmitin as well as in situ crystallisation experiments, monitored with neutron diffraction, conducted over three different cooling rates. We use the results from the high-resolution study to anticipate if neutron diffraction could be beneficial in differentiating the polymorphism in triacylglycerol systems. We extend on this to present analysis of a diffraction pattern of cocoa butter, to establish the potential for neutron diffraction to study the (hydrogenous) forms of triacylglycerols used in food production.

Effects of arginine on Polytomella parva growth, PII protein levels and lipid body formation.

L-Arginine supports growth and resulted in increased PII signaling protein levels and lipid droplet accumulation in the colorless green alga Polytomella parva. Polytomella parva, a model system for nonphotosynthetic green algae, utilizes ammonium and several carbon sources, including ethanol and acetate. We previously reported that P. parva accumulates high amounts of arginine with the key enzyme of the ornithine/arginine biosynthesis pathway, N-acetyl-L-glutamate kinase, exhibiting high activity. Here we demonstrate that L-arginine can be used by this alga as a nitrogen source. Externally supplied arginine directly influenced the levels of PII signaling protein and formation of triacylglycerol (TAG)-filled lipid bodies (LBs). Our results suggest that the nitrogen source, but not nitrogen starvation, may be critical for the accumulation of LBs in a PII-independent manner in P. parva.

Primary Metabolism in Avocado Fruit.

Avocado (Persea americana Mill) is rich in a variety of essential nutrients and phytochemicals; thus, consumption has drastically increased in the last 10 years. Avocado unlike other fruit is characterized by oil accumulation during growth and development and presents a unique carbohydrate pattern. There are few previous and current studies related to primary metabolism. The fruit is also quite unique since it contains large amounts of C7 sugars (mannoheptulose and perseitol) acting as transportable and storage sugars and as potential regulators of fruit ripening. These C7 sugars play a central role during fruit growth and development, but still confirmation is needed regarding the biosynthetic routes and the physiological function during growth and development of avocado fruit. Relatively recent transcriptome studies on avocado mesocarp during development and ripening have revealed that most of the oil is synthesized during early stages of development and that oil synthesis is halted when the fruit is harvested (pre-climacteric stage). Most of the oil is accumulated in the form of triacylglycerol (TAG) representing 60–70% in dry basis of the mesocarp tissue. During early stages of fruit development, high expression of transcripts related to fatty acid and TAG biosynthesis has been reported and downregulation of same genes in more advanced stages but without cessation of the process until harvest. The increased expression of fatty acid key genes and regulators such as PaWRI1, PaACP4-2, and PapPK-β-1 has also been reported to be consistent with the total fatty acid increase and fatty acid composition during avocado fruit development. During postharvest, there is minimal change in the fatty acid composition of the fruit. Almost inexistent information regarding the role of organic acid and amino acid metabolism during growth, development, and ripening of avocado is available. Cell wall metabolism understanding in avocado, even though crucial in terms of fruit quality, still presents severe gaps regarding the interactions between cell wall remodeling, fruit development, and postharvest modifications.

Molecular and biochemical analysis of the castor caruncle reveals a set of unique genes involved in oil accumulation in non-seed tissues

BackgroundWith the increasing demand for vegetative oil and the approach of peak seed oil production, it is important to develop new oil production platforms from non-seed tissues. Castor bean (Ricinus communis) is one of the crops for vegetable oil for industrial applications with yield around 1.4 ton oil per hectare produced in seed. The castor caruncle is a non-seed tissue attached to seed.ResultsCaruncle accumulates up to 40% oil by weight in the form of triacylglycerol (TAG), with a highly contrasting fatty acid composition when compared to the seed oil. Biochemical analysis indicated that the caruncle synthesizes TAGs independent of the seed. Such non-seed tissue has provided an excellent resource for understanding the mechanism of oil accumulation in tissues other than seeds. Transcriptome analysis revealed the key members of gene families involved in fatty acid synthesis and TAG assembly in the caruncle. A transient expression assay of these selected genes resulted in a 20-fold increased TAG accumulation in leaves.ConclusionsCastor caruncle utilizes an independent system to synthesize TAGs. Results provide the possibility of exploiting caruncle gene set to engineer oil production in non-seed tissues or microbes.

Nitrogen deprivation induces triacylglycerol accumulation, drug tolerance and hypervirulence in mycobacteria

Mycobacteria share with other actinomycetes the ability to produce large quantities of triacylglycerol (TAG), which accumulate as intracytoplasmic lipid inclusions (ILI) also known as lipid droplets (LD). Mycobacterium tuberculosis (M. tb), the etiologic agent of tuberculosis, acquires fatty acids from the human host which are utilized to synthesize TAG, subsequently stored in the form of ILI to meet the carbon and nutrient requirements of the bacterium during long periods of persistence. However, environmental factors governing mycobacterial ILI formation and degradation remain poorly understood. Herein, we demonstrated that in the absence of host cells, carbon excess and nitrogen starvation promote TAG accumulation in the form of ILI in M. smegmatis and M. abscessus, used as surrogate species of M. tb. Based on these findings, we developed a simple and reversible in vitro model to regulate ILI biosynthesis and hydrolysis in mycobacteria. We also showed that TAG formation is tgs1 dependent and that lipolytic enzymes mediate TAG breakdown. Moreover, we confirmed that the nitrogen-deprived and ILI-rich phenotype was associated with an increased tolerance towards several drugs used for treating mycobacterial infections. Importantly, we showed that the presence of ILI substantially enhanced the bacterial burden and granuloma abundance in zebrafish embryos infected with lipid-rich M. abscessus as compared to embryos infected with lipid-poor M. abscessus, suggesting that ILI are actively contributing to mycobacterial virulence and pathogenesis.

FAX2 Mediates Fatty Acid Export from Plastids in Developing Arabidopsis Seeds.

Vegetable oils are mainly stored in the form of triacylglycerol (TAG) in oilseeds. Fatty acids (FAs), one of the building blocks for TAG assembly, are synthesized in plastids and then exported to the endoplasmic reticulum for storage oil synthesis. A recent study demonstrated that the export of FAs from plastids was mediated by a FAX (FA export) family protein. However, the significance of FAs export from plastid during seed oil accumulation has not been investigated. In this study, we found that FAX2 was highly expressed in developing Arabidopsis seeds and the expression level was consistent with FAs synthesis activity. FAX2 mutant seeds showed an approximately 18% reduction of lipid levels compared with wild-type seeds. By contrast, overexpression of FAX2 enhanced seed lipid accumulation by up to 30%. The FAs export activity of FAX2 was confirmed by yeast mutant cell complementation analysis. Our results showed that FAX2 could interact with other proteins to facilitate FAs transport. Taken together, these results indicate that FAX2-mediated FA export from plastids is important for seed oil accumulation, and that FAX2 can be used as a target gene for increasing lipid production in oilseeds.

Protein S-acyl transferase 15 is involved in seed triacylglycerol catabolism during early seedling growth in Arabidopsis.

Seeds of Arabidopsis contain ~40% oil, which is primarily in the form of triacylglycerol and it is converted to sugar to support post-germination growth. We identified an Arabidopsis T-DNA knockout mutant that is sugar-dependent during early seedling establishment and determined that the β-oxidation process involved in catabolising the free fatty acids released from the seed triacylglycerol is impaired. The mutant was confirmed to be transcriptional null for Protein Acyl Transferase 15, AtPAT15 (At5g04270), one of the 24 protein acyl transferases in Arabidopsis. Although it is the shortest, AtPAT15 contains the signature 'Asp-His-His-Cys cysteine-rich domain' that is essential for the enzyme activity of this family of proteins. The function of AtPAT15 was validated by the fact that it rescued the growth defect of the yeast protein acyl transferase mutant akr1 and it was also auto-acylated in vitro. Transient expression in Arabidopsis and tobacco localised AtPAT15 in the Golgi apparatus. Taken together, our data demonstrate that AtPAT15 is involved in β-oxidation of triacylglycerol, revealing the importance of protein S-acylation in the breakdown of seed-storage lipids during early seedling growth of Arabidopsis.

Fatty Acid Composition and Lipid Profile of Oral/Enteral Nutrition Supplements Available on the Brazilian Market

Oral/enteral nutrition supplements enriched with fish oil are widely used for the recovery of the nutritional status of hospitalized patients, due to the omega‐3 fatty acids content. However, they are targets of adulteration. This study evaluates the lipid quality of five brands of oral/enteral nutrition supplements incorporated with fish oil, available on the Brazilian market (Brazil, Holland, and Germany). The fatty acids are quantified by gas chromatography–flame ionization detection, and the lipid profile is acquired by direct electrospray ionization–mass spectrometry, to assess how fatty acids are present in those samples. The eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents found ranged from 1.54 to 19.36% and 4.34 to 27.29%, respectively, in the form of triacylglycerols. However, brand 1 presents the lowest levels of EPA + DHA in its lipid composition, and in three brands, the addition of medium chain triglycerides is identified. The lipid quality assessment of these supplements allows an informed choice of appropriate supplements for the nutritional support of patients.Practical Applications: The study highlights and provides information of the lipid composition and fatty acids of oral/enteral nutrition supplements enriched with fish oil, indicated for malnourished patients. The findings allow health professionals to make a more informed choice of oral/enteral nutrition for the adequate treatment of patients.Fatty acids of five brands of oral/enteral nutrition supplements enriched with fish oil and available on the Brazilian market are quantified by gas chromatography–flame ionization detection, and the lipid profile is acquired by electrospray ionization–mass spectrometry. No lipid pattern among the samples is identified.

Enhancement of Algal Biofeedstocks in a Mixotrophic Batch Culture Supplemented with Exogenous Glycerol

Chlorella vulgaris is a fast growing, unicellular microalgae. With its limited nutritional requirements and ability to grow in adverse environments, it is a promising biodiesel feedstock that will not compete with agricultural resources.1 Published literature has shown C. vulgaris can produce up to 42% lipids per dry mass, the most desired of which are triacylglycerols (TAGs).2 TAGs consist of three fatty acids esterified to a glycerol backbone and are the most reduced, energy‐dense biomolecules. To generate drop‐in ready biodiesel, TAGs are transesterified to yield methyl‐ester alkyls and a glycerol byproduct.To realistically produce fuel on an industrial scale, microalgal TAG production must be increased beyond current levels. Previous work published by the Kolling Lab increased lipid accumulation in C. vulgaris by using an exogenous carbon source to form a heteromixotrophic culture, in which the cells are energetically supplemented by both exogenous carbon as well as photosynthetic light reactions.3 This project seeks to further increase TAG production by supplying cells with exogenous glycerol, thus providing a use for the transesterification byproduct while reducing the cellular energy investment for TAG production.While published studies have found 10 g/L glycerol to be optimal for lipid production in C. vulgaris, this was completed heterotrophically.4 While growing mixotrophically, we have increased lipid accumulation beyond previously published glycerol studies and have increased overall lipid productivity in glycerol concentrations of 31.5 and 63 g/L. We also monitored photosynthetic performance before and after glycerol addition and observed an increased reliance on cyclic electron transport (a mode of photosynthesis that does not result in the production of NADPH), indicating that the ATP need is greater than that of NADPH for TAG formation under photomixotrophic conditions. Finally, using isotopically labeled glycerol, we have used GC‐MS to determine the rate of glycerol uptake and that exogenously provided glycerol is directly used for the TAG backbone and not metabolized for the generation of fatty acids.Support or Funding InformationThis material is based upon work supported by the National Science Foundation under Cooperative Agreement No. OIA‐1458952.Amanda Smythers acknowledges a fellowship from the NASA West Virginia Space Grant Consortium, Grant #NNX15AK74A and Training Grant # NNX15AI01H.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Influence of Nitrogen Limitation on Lipid Accumulation and EPA and DHA Content in Four Marine Microalgae for Possible Use in Aquafeed

Microalgae are regarded as a promising alternative that can replace fishmeal and fish oil in aquaculture. Under N-limitation, many microalgae species change their carbon storage patterns in favor of neutral lipids (NLs) mainly in the form of triacylglycerol (TAG), but fatty acids in polar lipids (PL) are nutritionally more available for fish than those esterified into NLs. In the present study, the effect of N-limitation on the lipid content and fatty acid profiles in different lipid class of Phaeodactylum tricornutum, Isochrysis aff. galbana clone T-Iso, Rhodomonas baltica and Nannochloropsis oceanica were investigated. The microalgae cells were cultivated by two different methods, batch and semi-continuous culture, to create strong and moderate N-limitation, and this in turn will significantly affect the biomass and lipid productivity. All four species accumulated lipids mainly in the form of TAG in response to strong nitrogen limitation. N. oceanica, however accumulated 51% of the dry weight as lipid in moderate nitrogen limitation and up to 87% of the fatty acid was in TAG. Isochrysis aff. galbana clone T-Iso was the only species where the fraction of polyunsaturated fatty acid (PUFA), especially the fraction of docosahexaenoic acid (DHA) increased with increasing nitrogen limitation. Total lipid productivity showed no increase in batch culture although stronger nitrogen limitation led to lipid accumulation. P. tricornutum had the highest eicosapentaenoic acid (EPA) content, while N. oceanica showed the highest EPA productivity due to the high content of lipid. The highest DHA productivity was found in Isochrysis aff. galbana clone T-Iso from moderate N-limitation mainly due to the high biomass productivity. Based on the results from the current study, N. oceanica and T-Iso are two promising microalgae strains as long-term sustainable source of n-3 long chain -PUFAs under moderate N-limitation. As shown in the present study, increased lipid content in microalgal cells due to strong N-limitation induction may not increase the lipid productivity because biomass production usually is reduced. Therefore, a combination of approaches such as metabolic engineering, conditioning and selection may be needed to further increase the n-3 LC-PUFA productivity without substantial loss of biomass.

It takes a village: channeling fatty acid metabolism and triacylglycerol formation via protein interactomes

Diet, hormones, gene transcription, and posttranslational modifications control the hepatic metabolism of FAs; metabolic dysregulation causes chronic diseases, including cardiovascular disease, and warrants exploration into the mechanisms directing FA and triacylglycerol (TAG) synthesis and degradation. Long-chain FA metabolism begins by formation of an acyl-CoA by a member of the acyl-CoA synthetase (ACSL) family. Subsequently, TAG synthesis begins with acyl-CoA esterification to glycerol-3-phosphate by a member of the glycerol-3-phosphate acyltransferase (GPAT) family. Our studies of the isoforms ACSL1 and GPAT1 strongly suggest that these proteins are members of larger protein assemblies (interactomes). ACSL1 targeted to the ER interacts with peroxisomal, lipid droplet, and tethering proteins, uncovering a dynamic role for ACSL1 in organelle and lipid droplet interactions. On the outer mitochondrial membrane (OMM), PPARα upregulates ACSL1, which interacts with proteins believed to tether lipid droplets to the OMM. In contrast, GPAT1 is upregulated nutritionally by carbohydrate and insulin in a coordinated sequence of enzyme reactions, from saturated FA formation via de novo lipogenesis to FA esterification by GPAT1 and entry into the TAG biosynthesis pathway. We propose that involved enzymes form a dynamic protein interactome that facilitates esterification and that other lipid-metabolizing pathways will exist in similar physiologically regulated interactomes.

Proteomic study uncovers molecular principles of single-cell-level phenotypic heterogeneity in lipid storage of Nannochloropsis oceanica

BackgroundNannochloropsis oceanica belongs to a large group of photoautotrophic eukaryotic organisms that play important roles in fixation and cycling of atmospheric CO2. Its capability of storing solar energy and carbon dioxide in the form of triacylglycerol (TAG) of up to 60% of total weight under nitrogen deprivation stress sparked interest in its use for biofuel production. Phenotypes varying in lipid accumulation among an N. oceanica population can be disclosed by single-cell analysis/sorting using fluorescence-activated cell sorting (FACS); yet the phenomenon of single cell heterogeneity in an algae population remains to be fully understood at the molecular level. In this study, combination of FACS and proteomics was used for identification, quantification and differentiation of these heterogeneities on the molecular level.ResultsFor N. oceanica cultivated under nitrogen deplete (−N) and replete (+N) conditions, two groups differing in lipid content were distinguished. These differentiations could be recognized on the population as well as the single-cell levels; proteomics uncovered alterations in carbon fixation and flux, photosynthetic machinery, lipid storage and turnover in the populations. Although heterogeneity patterns have been affected by nitrogen supply and cultivation conditions of the N. oceanica populations, differentiation itself seems to be very robust against these factors: cultivation under +N, −N, in shaker bottles, and in a photo-bioreactor all split into two subpopulations. Intriguingly, population heterogeneity resumed after subpopulations were separately recultivated for a second round, refuting the possible development of genetic heterogeneity in the course of sorting and cultivation.ConclusionsThis work illustrates for the first time the feasibility of combining FACS and (prote)-omics for mechanistic understanding of phenotypic heterogeneity in lipid-producing microalgae. Such combinatorial method can facilitate molecular breeding and design of bioprocesses.

Let's face the fats: palmitate restores cellular redox state in the diabetic heart.

Let's face the fats: palmitate restores cellular redox state in the diabetic heart.

Docosahexaenoic acid (22:6n-3) Ameliorated the Onset and Severity of Experimental Autoimmune Encephalomyelitis in Mice.

Multiple sclerosis (MS) is a neurologic autoimmune disease, which is the leading cause of nontraumatic neurologic disability in young adults in United States and Europe. n-3 polyunsaturated fatty acids (PUFA) are reported to mitigate severity of this disease. Recent studies suggest that phospholipid (PL) form of dietary n-3 PUFA may lead to their higher tissue accretion than triacylglycerol (TAG) form. We compared efficacy of PL-docosahexaenoic acid (22:6n-3) (DHA) and TAG-DHA on onset and severity of experimental autoimmune encephalomyelitis (EAE) in a mouse model of MS. Female mice were fed low alpha-linolenic acid (18:3n-3) (ALA) diet (control) for 2 weeks and then fed either control, 0.3%, or 1.0% DHA (PL or TAG) for 4 weeks pre-EAE induction and 4 weeks post-EAE induction. The brain and spinal cord n-6:n-3 ratio was significantly lower in all mice fed DHA compared to control. EAE onset was delayed in mice fed both DHA forms and concentrations, except for 1% TAG-DHA. The inverse association between the EAE score and the brain DHA concentration was nonsignificant at the end of the study (p = 0.08). Daily EAE scores of mice fed different DHA diets did not differ from control, however, the score of all DHA groups combined during days 9-16 was lower (p = 0.028) compared to the control. During days 17-22, the EAE score trended lower in 0.3% TAG-DHA and during days 23-28, the EAE score trended lower in both PL-DHA groups than those in all other groups. These findings suggest that TAG-DHA may be more effective than PL-DHA in the early phases of EAE, and in the final outcome, PL-DHA may be more effective than TAG-DHA.

Relationship between tocopherols depletion and polymerised triacylglycerols formation during heating of vegetable oils

Alpha tocopherol and total tocopherols depletion in relation to polymerised triacylglycerols formation were studied during the heating of nine vegetable oils (olive, palm, peanut, sunflower, rapeseed, soybean, grapeseed, maize and rice) at oil temperature 180°C (as a typical temperature during frying practise). It was observed that the rate of tocopherols depletion (expressed as the function of polymerised triacylglycerols content) decreased with the increasing degree of unsaturation and total antioxidant capacity of the tested oils (P < 0.05). Consequently, no tocopherols were present in olive, peanut and palm oil at their half lifespan (i.e., at 6% of polymerised triacylglycerols), whereas tocopherols in maize, sunflower, grapeseed, rice and, particularly, soybean oil were present even at the end of their lifespan, (i.e., at 12% polymerised triacylglycerols). These findings have not been published yet, or only little published.

Unraveling the Complexity of Milk Fat Globules to Tailor Bioinspired Emulsions Providing Health Benefits: The Key Role Played by the Biological Membrane

Many food products are oil in water (O/W) emulsions. Milk has the specificity to be a natural O/W emulsion secreted by the lactating cells. The milk fat globules are recognized as being efficient conveyors of energy in the form of triacylglycerols and of bioactive molecules, specifically provided by the biological membrane, the MFGM, which is the interface with the gastrointestinal tract. However, the MFGM is altered in many processed dairy products and is currently absent from standard infant milk formulas. The objectives of this invited article are to evaluate whether the specific composition and structure of the MFGM and milk polar lipid assemblies, associated with their nutritional and health benefits, could be used to tailor functional emulsions bioinspired by the MFGM‐coated milk fat globules. Recent knowledge about the structure of the MFGM revealing the heterogeneous distribution of proteins and the formation of ordered lipid domains rich in milk sphingomyelin and cholesterol is presented. The impacts of the unique composition and biophysical properties of milk polar lipids on the structure and potential functions of the MFGM are highlighted. Facing the evidence of both the functional and health benefits provided by the MFGM, the preparation of MFGM‐enriched ingredients from dairy products has recently attracted wide attention. The utilization of MFGM components to tailor the surface of processed lipid droplets in food emulsions and to develop new products providing health benefits is discussed.The biological membrane surrounding milk fat globules, the milk fat globule membrane (MFGM), is of special interest for its functional and health benefits. However, the MFGM is altered in many processed dairy products and is currently absent from standard infant milk formulas, in which the processed lipid droplets are coated by milk proteins. The preparation of MFGM‐enriched ingredients from dairy products is possible at the industrial scale. The utilization of MFGM components to tailor the surface of processed lipid droplets in food emulsions will permit the development of new products providing health benefits.

ANÁLISIS DE LAS CINÉTICAS DE TERMOXIDACIÓN DE GRASA BOVINA

The thermoxidation of four different milk fat samples was studied using isoconversional method. The milk samples contained different ratio of unsaturated to saturated fatty acids of 0.7, 0.86, and 1.36 (MF1, MF2, and MF3, respectively), and a hydrolyzed milk fat sample (90% free fatty acids) with a ratio of 1.40 (MF4). The thermoxidation has been conducted under non-isothermal oxidation from 380 to 520K using five different heating rates (3, 6, 9, 12and 15 K min -1 ). The Kissinger-Akahira-Sunose (KAS) method was used to calculate the activation energy as a function of the extend of themroxidation. The obtained dependencies were interpreted in terms of oxidation mechanisms. The activation energy values were 100.10, 84.53, 80.41, and 121.44 kJ mol -1 for MF1, MF2, MF3, and MF4, respectively. The thermoxidaiton of milk fat in the form of triacylglycerol was best described by Avrami-Erofeev model (A3), while the thermoxidation of free fatty acids was described by a frist-order model (F1). The calculated kinetic triplet were used to simulate the thermoxidation of milk fat and showed good agreement with the experimental data.