Hydrogenation Of Vegetable Oils Research Articles

Computational fluid dynamics in the development of catalytic reactors

Computational fluid dynamics is becoming an important tool in the study of chemical engineering processes and apparatuses (in particular, the share of works with the application of this method is nearly 6% of the total number of all chemical engineering works issued by Elsevier Science Publishers in 2010). The possibilities of computational fluid dynamics are demonstrated using examples from three different chemical engineering fields: developing a method for loading a tubular reactor for the steam conversion of natural gas, studying heat transfer in a reactor for the hydrogenation of vegetable oils upon the replacement of a catalyst, and investigating the transitional processes in an automobile neutralizer. The results from computational fluid dynamics are verified by comparing them with experimental data in developing a method for loading a tubular reactor, using the problem of decelerating a catalyst particle with a flow of air as an example. The obtained data are compared with classical measurement data on the aerodynamic drag of a ball and a cylinder and represent the further development of works on the flow around particles of complex shape. In this work, the results from inspecting a reactor for the hydrogenation of oils with allowance for the possible heating and uniform distribution of a flow before its entering the catalyst bed are presented. It is shown that the construction of the reactor does not ensure homogeneity of the reaction flow at the desired level and requires modification of heating elements. The efficiency of computational fluid dynamics for investigating fast processes with a chemical reaction is exemplified by studying the transitional processes in an catalytic automobile neutralizer (the effect of flow dynamics and heat transfer on the thermal regime in a honeycomb catalyst particle is very difficult to study by experimental methods). The application of computational fluid dynamics allows us to reduce considerably the time and cost of developing and optimizing the designs of efficient catalytic fixed-, fluidized-, or moving-bed reactors (particularly multiphase stirred (slurry) reactors), along with mixers, adsorbers, bubblers, and other chemical engineering apparatuses with moving media.

Surface properties of the Ni-silica gel catalyst precursors for the vegetable oil hydrogenation process: N2 sorption and XPS studies

The effect of the type of the silica gel pore structure on the surface properties of the Ni-silica gel catalyst precursors for the vegetable oil hydrogenation process has been examined applying N2 sorption and X-ray photoelectron spectroscopy techniques. The nickel catalyst precursors with identical composition (SiO2/Ni = 1.0) has been synthesized by precipitation of Ni(NO3)2 · 6H2O solution with Na2CO3 solution on the three types of silica gel with different pore structures. It is shown that the usage of the silica gel supports with different texture as source of SiO2 causes different location of Ni-species into the support pores and on the external surface area. The XPS data confirm the formation of surface species with different strength of interaction and different dispersion. These surface characteristics of the precursors will predetermine the formation of the active nickel metallic phase as well as the mass transfer of the reactants and products to and from the catalytic sites.

Conjugated linoleic acid formation by hydrogenation/isomerisation of safflower oil over bifunctional structured catalyst Rh/SBA‐15

AbstractDirected isomerisation of safflower oil under very low hydrogen partial pressure of 7 psi over a novel bifunctional highly structured rhodium‐based catalyst (Rh/SBA‐15), having narrow pore size distribution ranging from 4 to 8 nm, and BET‐specific surface of ≈1,000 m2 g−1, was investigated as a new chemocatalytic approach for vegetable oil hardening and simultaneously producing health‐beneficial conjugated linoleic acids (CLA). Time course profiles of (cis‐9, trans‐11)‐; (cis‐10, trans‐12)‐; (trans‐10, cis‐12)‐; (cis,cis)‐ and (trans, trans)‐octadecadienoic isomers (CLAs) as well as the other fatty acids traditionally encountered during the hydrogenation of vegetable oils are presented and discussed under selected process conditions. Preliminary results show that it is possible to tailor characteristics of the hydrogenation catalyst in such way to confer its bi‐functional activity: hydrogenation and conjugation isomerisation. © 2011 Canadian Society for Chemical Engineering

Ecological-Level Associations Between Highly Processed Food Intakes and Plasma Phospholipid Elaidic Acid Concentrations: Results From a Cross-Sectional Study Within the European Prospective Investigation Into Cancer and Nutrition (EPIC)

Elaidic acid is the main unnatural trans fatty acid isomer occurring during partial hydrogenation of vegetable oils used as ingredients for the formulation of processed foods. The main objective is to assess associations between processed food intakes and plasma phospholipid elaidic acid concentrations within the European Prospective Investigation into Cancer and Nutrition study. A cross-sectional study was used to determine fatty acid profiles in 3,003 subjects from 16 centers. Single 24-h dietary recalls (24-HDR) were collected using a standardized computerized interview program. Food intakes were computed according to their degree of processing (moderately/nonprocessed foods, processed staple foods, highly processed foods). Adjusted ecological and individual correlations were calculated between processed food intakes and plasma elaidic acid levels. At the population level, mean intakes of highly processed foods were strongly correlated with mean levels of plasma elaidic acid in men (P = 0.0016) and in women (P = 0.0012). At the individual level, these associations remained but at a much lower level in men (r = 0.08, P = 0.006) and in women (r = 0.09, P = 0.0001). The use of an averaged 24-HDR measure of highly processed food intakes is adequate for predicting mean levels of plasma elaidic acid among European populations.

A rheological analysis of structured water-in-olive oil emulsions

Structured emulsions are widely used in the food industry. In the case of water-in-oil emulsions, an oil phase structuration is achieved by the creation of a saturated fat crystalline network inside which water droplets are entrapped. Traditional technology based on the hydrogenation of vegetable oils, leads to the formation of saturated trans-fatty acids, considered unhealthy owing to their potential contribution to cardio-vascular diseases. As a consequence, nowadays the use of hydrogenated fatty acids has been reduced and the consumption of healthy oils has increased. However oils need to be properly structured to be used as solid fat replacers. The present work deals with the rheological study of W/O emulsions, structured through the oil phase crystallisation by organogelator agents (mono- and di-glycerides of fatty acids). The oil phase was prepared by blending a high-oleic-acid-containing oil (olive oil) with a natural saturated fatty acids source (cocoa butter). A highly structured network is obtained by rapidly cooling the molten oil phase at low shear rates. The emulsions prepared were compared with commercial margarines and they showed rheological properties suitable to a potential application as “solid fats”.

Overview of trans fatty acids: Biochemistry and health effects

Trans fatty acids (TFA) are unsaturated fatty acids that contain at least one non-conjugated double bond in the trans configuration, resulting in a straighter shape. TFA present in our diet can either be industrially produced and ruminant or natural. The major process contributing to formation of industrial TFA is hydrogenation of vegetable oils. Thermal processes such as edible oil refining and frying also lead to the formation of TFA while, ruminant/natural TFA is formed in the rumen of ruminant animals through bio-hydrogenation. Industrial TFA poses severe effects on our health like cardiovascular problems, insulin resistance, infertility in women, compromised fetal development and cognitive decline. There are strict regulations for limiting/removing the TFA content from food supply across the world. However in India, there is scarcity of data on TFA content in foods and their consumption levels. Given the alarmingly rising trend of diabetes and cardiovascular disease in India, removal of TFA from the food supply along with generating awareness among the masses in this regard is of immense importance.

Effects of ruminant trans fatty acids on cardiovascular disease and cancer: a comprehensive review of epidemiological, clinical, and mechanistic studies.

There are 2 predominant sources of dietary trans fatty acids (TFA) in the food supply, those formed during the industrial partial hydrogenation of vegetable oils (iTFA) and those formed by biohydrogenation in ruminants (rTFA), including vaccenic acid (VA) and the naturally occurring isomer of conjugated linoleic acid, cis-9, trans-11 CLA (c9,t11-CLA). The objective of this review is to evaluate the evidence base from epidemiological and clinical studies to determine whether intake of rTFA isomers, specifically VA and c9,t11-CLA, differentially affects risk of cardiovascular disease (CVD) and cancer compared with iTFA. In addition, animal and cell culture studies are reviewed to explore potential pro- and antiatherogenic mechanisms of VA and c9,t11-CLA. Some epidemiological studies suggest that a positive association with coronary heart disease risk exists between only iTFA isomers and not rTFA isomers. Small clinical studies have been conducted to establish cause-and-effect relationships between these different sources of TFA and biomarkers or risk factors of CVD with inconclusive results. The lack of detection of treatment effects reported in some studies may be due to insufficient statistical power. Many studies have used doses of rTFA that are not realistically attainable via diet; thus, further clinical studies are warranted. Associations between iTFA intake and cancer have been inconsistent, and associations between rTFA intake and cancer have not been well studied. Clinical studies have not been conducted investigating the cause-and-effect relationship between iTFA and rTFA intake and risk for cancers. Further research is needed to determine the health effects of VA and c9,t11-CLA in humans.

Palladium catalyst on anodized aluminum monoliths for the partial hydrogenation of vegetable oil

The present work explores the viability of introducing improvements to the conventional process of hydrogenation using structured catalysts. Monolithic catalysts of anodized aluminum were prepared and characterized. They were impregnated with palladium and used as monolithic stirrers in the sunflower oil hydrogenation reaction at 100 °C and 413 kPa. The monolithic catalysts showed to be active, with a 50% C C conversion in 30 min. When consecutive tests were performed, a loss of activity was observed, decreasing 80% in the sixth test, which is attributed to the presence of carbonaceous residues.

An alternative process for hydrogenation of sunflower oil

Classic methodologies for hydrogenation of vegetable oils have traditionally been carried out by nickel catalysts under high pressure of H2 and high temperature. An alternative method for hydrogenation of sunflower oil using limonene and palladium-on-carbon was investigated in this study. The use of limonene as a hydrogen donor solvent was proposed in order to avoid high temperature and high-pressure conditions. The catalytic transfer of hydrogenation was studied by using 0.5 to 2% of Pd as a catalyst, a limonene:oil ratio of 3:1, and reaction times from 0.5 to 2 hours. Under these conditions, high selectivities for oleic acid and low concentrations of stearic acid were obtained.

Conjugated linoleic acid formation via heterogeneous hydrogenation/isomerization of safflower oil over mesostructured catalysts

Aluminum-containing SBA-15 mesoporous molecular sieves with different nominal molar ratios Si/Al = 5, 10, 20, 50 and 100 were prepared via direct synthesis by adjusting the pH of gel synthesis just below the isoelectric point of silica (pH = 1.9 < 2). The aluminum incorporation yield in all of those materials is about 80% which is one of the highest ever reported. The calcined materials were characterized by XRD, N 2 physisorption, TEM, and 27Al NMR methods. These investigations confirm that the 2-D hexagonal mesoporous structure is maintained for all Si/Al ratios, and 27Al NMR analysis indicates that aluminum is almost in tetrahedral coordination. Among metals investigated, rhodium in metallic state, highly dispersed on Al_SBA-15(1 0 0) with a pore size ranging from 4 to 7 nm, BET-specific surface of 1000 m 2 g −1, and metal nominal total loading of 1% w/w, was revealed as a new active catalyst for the chemocatalytic vegetable oils modification inducing health-beneficial conjugated linoleic acids (CLA) formation by hydrogenation/isomerization. Time course profiles of (9- cis, 11- trans)-; (10- cis, 12- trans)-octadecadienoic CLA isomers as well as the other fatty acids traditionally encountered during the hydrogenation of vegetable oils are presented and discussed for the Rh-catalyst supported on Al_SBA-15 using Si/Al ratio of 100 under selected process conditions. The results show that it is possible to tailor characteristics of the hydrogenation catalyst in such a way to confer it bifunctional activity: hydrogenation and conjugated isomerization.

Production of Low‐trans Fatty Acids Edible Oil by Electrochemical Hydrogenation in a Diaphragm Reactor Under Controlled Conditions

AbstractElectrochemical hydrogenation is a novel, alternative process for selective hydrogenation of vegetable oils, because of its high extent of hydrogenation and low trans‐isomer formation. Electrochemical hydrogenation of soybean oil in a diaphragm reactor with a formate ion concentration of 0.4 mol/l at pH 5.0 under moderate temperature conditions using a current density of 10 mA/cm2 was investigated to identify the critical conditions affecting the selective hydrogenation reaction and the resulting fatty acid profile. The optimum composition was an oil‐to‐formate solution ratio of 0.3 (w/w), 2–3 g EDDAB in 100 g soybean oil, and 0.8% Pd–C catalyst loading. The electrochemical hydrogenation reaction of soybean oil was described by first‐order kinetics, and the kinetic rate constants and reaction selectivity were determined accordingly. Re‐use of the Pd–C catalyst up to five times was found to be acceptable. A comprehensive evaluation revealed that the most significant conditions affecting the extent of hydrogenation and the trans fatty acids content of final products were operating temperature, pH of the formate solution, and catalyst loading.

Effects of trans fatty acid (tFA)‐free fat formulations on lipid and lipoprotein metabolism in gerbils and hamsters

The adverse health effects of dietary tFA resulting from the partial hydrogenation of liquid vegetable oils (PHVO) have prompted health agencies to advocate their reduction or complete elimination from the food supply. Alternatives to PHVO are being considered, including genetically modified oils with reduced PUFA, interesterified fats high in stearic acid, and naturally occurring oil blends with increased SFA. In the current study, we evaluated various oil blends‐ soybean oil (SO), low‐linoleic SO, interesterified SO, coconut oil, a vegetable‐oil blend (palm, corn &amp; sunflower) and a palm oil fraction with an increased content of oleic acid for their effects on lipid and lipoprotein metabolism. In all, 96 male Mongolian gerbils and 75 male Golden Syrian hamsters were fed purified diets for 4 weeks containing ~ 30% calories from the test fat blends and ~0.1% w/w cholesterol. Plasma lipids, lipoprotein concentrations, composition, and particle sizes, and liver free and esterified cholesterol were measured. Despite minor differences between individual diets, only the coconut oil‐based diet (99% coconut oil, 1% SO) induced hypercholesterolemia in both species. These data suggest that within the context of currently recommended prudent diets, various tFA‐free fat formulations can be utilized without compromising plasma lipids. Whether the same occurs in humans is under investigation.

Health Hazards From Trans Fatty Acids: Ban of Artificial Trans Fats Long Overdue

EFSA 12.00 Normal 0 false false false EL X-NONE X-NONE MicrosoftInternetExplorer4 EFSA 12.00 Normal 0 false false false EL X-NONE X-NONE MicrosoftInternetExplorer4 Although we are all abundantly aware of the health risk of saturated fat, not much attention and proper warning is given to the even more hazardous effects of unsaturated trans fatty acids. Trans fatty acids (TFA) are created by the partial hydrogenation of vegetable oils, a process converting them into semisolid fats for use in margarines, commercial cooking, and manufacturing processes, as they offer certain commercial advantages . However, major concern has been raised for TFA as they are associated with an elevated risk of ischemic heart disease (IHD). Trans fat behaves similar to saturated fat by raising LDL levels, but furthermore, it has the additional effect of decreasing HDL levels. Health authorities should advise the public to minimize the intake of trans fats, to recognize and avoid foods containing trans fats, and impose rules and regulations restricting TFA in the industry and the restaurants and thus prevent thousands of IHD events each year worldwide.

Trans fatty acids and coronary artery disease

Correspondence: Jocelyne Benatar Cardiovascular research Unit, Green Lane Cardiovascular Service, Auckland City Hospital, Auckland 1030, New Zealand Tel +64 9 307 4949 Fax +64 9 630 9978 email jbenatar@adhb.govt.nz Abstract: There has been a significant increased consumption of trans fats in the developed world as we have embraced processed and take away foods in our diet in the last 40 years. These fatty acids are not essential for human nutrition and are hazardous to health. They increase the risk of cardiovascular disease more than any other macronutrient including saturated fat, through multiple mechanisms including adverse effects on lipids, endothelial function and inflammation. They are readily incorporated into cell structures such as cell membranes and the Golgi apparatus, resulting in unintended effects on multiple biological pathways. The majority of trans fats in our diet are artificially manufactured by a process of partial hydrogenation of vegetable oil with little coming from natural sources. It should be possible to replace these harmful fats in the food chain at source with concerted efforts from food manufacturers and legislators.

Partial hydrogenation of soybean oil using metal-decorated integral-asymmetric polymer membranes: Effects of morphology and membrane properties

Three phase reaction schemes pose numerous challenges to reactor design due to the slow diffusional mass transfer of reactants from the gas phase through a liquid to the active sites of the catalyst. An example is partial hydrogenation of vegetable oil which is traditionally carried out in a batch autoclave by bubbling hydrogen gas though a slurry of oil and solid catalyst particles containing Ni. Unwanted trans fatty acids (TFAs) are formed during this process due to the scarcity of hydrogen at the active catalyst sites. Here we investigate the use of metal-decorated integral-asymmetric polymer membranes to enable the supply of dissolved hydrogen near the location where the liquid oil phase contacts the catalyst. Hydrogen gas is supplied to the porous substructure of the asymmetric membrane where it dissolves in the thin skin layer of the membrane and emerges as dissolved hydrogen on the metal-decorated side of the membrane where the oil is present. Temperature and pressure are compatible with existing facilities. All membranes produced low TFA (2.6–4.6 wt% at Iodine Value of 95) compared to the slurry process. A 1000 metric ton per day soybean oil hydrogenation facility would require 2–3000 m 2 membrane area with a total of 90 g of Pt metal catalyst. This could be envisioned as metal sputtered hollow fibers packaged in conventional modules.

A kinetic study of the electrochemical hydrogenation of ethylene

In this study, we have examined the kinetics of the electrochemical hydrogenation of ethylene in a PEM reactor. While in itself this reaction is of little industrial interest, this reaction can be looked upon as a model reaction for many of the important hydrogenation processes including the refining of heavy oils and the hydrogenation of vegetable oils. To study the electrochemical hydrogenation of ethylene, several experimental techniques have been used including polarization measurements, measurement of the composition of the exit gases and potential step, transient measurements. The results show that the hydrogenation reaction proceeds rapidly and essentially to completion. By fitting the experimental transient data to the results from a zero-dimensional mathematical model of the process, a set of kinetic parameters for the reactions has been obtained that give generally good agreement with the experimental results. It seems probable that similar experimental techniques could be used to study the electrochemical hydrogenation of other unsaturated organic molecules of more industrial significance.

High Oleic and Low Trans Fatty Acid Formation by an Electrochemical Process

AbstractElectrochemical hydrogenation employing a mediator of formate/formic acid resulted in partial hydrogenation of vegetable and soybean oil at 20–40 °C and ambient pressure when palladium supported on alumina was employed as a catalyst. An oleic acid content of 48% with a corresponding iodine value of 81 for the vegetable oil hydrogenated at 20 °C was obtained. The total trans fatty acid content and especially the 18:1 trans fatty acid were found to increase with the reaction temperature and time. Nonetheless, relatively low total trans and 18:1 trans fatty acid (7 and 3.8%, respectively) contents were found when the vegetable oil was partially hydrogenated to achieve an iodine value of 112.

Acides gras trans: effets sur le métabolisme des lipoprotéines et le risque cardiovasculaire

Dietary trans fatty acids (TFA) (mainly 18:1 isomers) have two sources: they are formed during the natural bacterial hydrogenation of unsaturated fatty acids in ruminants or they come from the industrial hydrogenation of unsaturated vegetable oils. Total trans fatty acids account for 1.3% of total energy intake in France compared to 2-3% in USA. Recent epidemiologic studies and meta-analyses of well-designed controlled trials clearly showed that trans fatty acids are associated with an increase of cardiovascular risk. It seems that TFA from industrial sources are responsible for the deleterious effects particularly on lipoprotein metabolism. Specifically the consumption of industrial TFA has been associated with high plasma concentrations of triacylglycerols, LDL-cholesterol and small dense LDL and lower HDL-cholesterol concentrations. The very recent interventional trials allowed for a comparison of TFAs from different sources suggest that the intake of natural TFA have no or neutral effects on plasma lipids and other cardiovascular risk factors. However, the mechanisms underlying the isomer-specific effects are not well understood and warrant further investigations.

Ácidos grasos trans (AGt): fuentes y niveles de ingesta, efectos biológicos y contenido en los alimentos comerciales españoles

Recent studies of dietary habits in children and adolescents performed in Spain show that a high percentage of the daily energy intake corresponds to fat (42.0-43.0%). These findings show an excessive contribution of saturated fatty acids and also a considerable supply of trans fatty acids. These compounds are formed generally during partial hydrogenation of vegetable oils, a process that converts vegetable oils into semisolid fats. Also, in some cases naturally occurring trans fatty acids in smaller amounts in meat and dairy products from ruminants (cows, sheep), these trans fatty acids are produced by the action of bacteria in the ruminant stomach by reactions of biohydrogenation. On the other hand, metabolic studies have clearly shown that trans fatty acids increase LDL cholesterol and reduce HDL cholesterol. Our results show that major sources of trans fatty acids in commercial Spanish foods are fast-food (hamburger, French fries), snacks, bakery products (cakes, donuts, biscuits), margarines and dehydrated soups.

Feasibility of recommending certain replacement or alternative fats

Expert groups and public health authorities recommend that trans-fatty acid (TFA) intakes from industrially produced partially hydrogenated vegetable oils (PHVOs) should be less than 1% of total energy intake. The starting point for any regulatory or nonregulatory response to this recommendation is to assess the extent of the problem by determining where in the food supply TFAs are found and the amounts consumed in the population. Unfortunately, this is a particularly difficult task using traditional methods of dietary assessment inasmuch as food composition databases with TFA data are either nonexistent or incomplete in most countries. Current evidence on estimates of intake suggests there is high variability in TFA intakes and their food sources between countries. The ubiquitous presence of PHVOs in the global food supply in bakery products, deep-fried foods, snack foods, confectionery products and table spreads attests to their commercial value and convenience. However, their common use is more the result of historical convenience from an industry infrastructure developed over 50 years based on efficient, cost-effective hydrogenation of vegetable oils rather than any inherent sensory or physical superiority of the hydrogenated fats over purpose-made zero-trans fats and oils. Current global supply of appropriate zero-trans replacement fats high in cis-unsaturated fatty acids is insufficient to meet the demand if all PHVOs in the food supply were replaced. Regulatory action needs to be coordinated with supply to maximize the opportunity for health gains by replacing partially hydrogenated fats with purpose-ready zero-trans vegetable oils low in saturates and high in cis-unsaturates rather than animal fats and tropical oils high in saturated fatty acids.