Hydrogenation of Low Erucic Acid Rapeseed Oil

The effects of some process conditions on the overall reaction rate and on trans isomer formation during hydrogenation of low erucic acid rapeseed oil with a commercial nickel catalyst were studied. Experimental data were correlated by an empirical equation which would be used to predict the reaction rate constants for any given process conditions. Temperature had a major effect on rate and trans isomer formation. Pressure and catalyst concentration, however, had only minor effects. It is suggested that apart from these factors, the extent of trans isomer formed is also controlled by the nature and amount of the unsaturation in the oil and by the overall reaction rate. A new parameter, specific isomerization index was introduced to represent the formation of trans isomers during the hydrogenation reaction. The effects of solvents n-hexane and 2-propanol on the reaction rate and trans isomers formation were determined.     

Modification of vegetable oils. XI. The formation of trans isomers during the hydrogenation of methyl oleate and triolein

Summary 1. During the hydrogenation of methyl oleate, trans isomers are formed at a very rapid rate. As much as 38% of trans isomers formed while the first 10% of methyl stearte was formed. 2. The rate of formation of trans isomers in methyl oleate undergoing hydrogenation is increased by increasing the temperature, increasing the catalyst concentration, and decreasing the degree of dispersion of the hydrogen. 3. The hydrogenation of methyl oleate always resulted in the establishment of an equilibrium between cis and trans isomers, and irrespective of the conditions employed the concentration of trans isomers was always 67%, calculated on the basis of total unsaturated constituents. 4. It is concluded that all of the iso-oleic acids formed during the hydrogenation of methyl oleate adsorb hydrogen at the same rate as oleic acid and are adsorbed and desorbed from the nickel catalyst with equal ease. 5. Trans isomers are formed at a slightly lower rate during the hydrogenation of triolein than in the case of methyl oleate. 6. Partial hydrogenation of triolein also results in the establishment of an equilibrium between cis and trans isomers of oleic acid but at values of less than 67% of trans constituents (based on the total unsaturated constituents) observed with methyl oleate. The equilibrium concentration was found to vary with the conditions of hydrogenation and was found to be 62% at 200°C. and 57% at 175°C. Report of study made under the Research and Marketing Act of 1946. Presented at the 24th Fall Meeting of the American Oil Chemists’ Society, San Francisco, Calif., Sept. 26–28, 1950. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Hydrogenation of a menhaden oil: II. Formation and evolution of the C20 dienoic and trienoic fatty acids as a function of the degree of hydrogenation

To complement studies on monoethylenic fatty acids produced from the major polyunsaturated fatty acid (20:5A5,8,11,14,17) during hydrogenation of a menhaden oil of iodine value (IV) 159, the C₁₀ dienoic and trienoic fatty acid isomers of partially hydro-genated menhaden oils (PHMO) of IV 131.5, 96.5 and 85.5 were isolated by a combination of preparative gas liquid chromatography (GLC), mercuric adduct fractionation, and silver nitrate thin layer chromatography (AgNO₃-TLC). The 20:2 fatty acid methyl esters of the three PHMO samples were transformed to the corresponding alcohols and ozonized in BF₃-MeOH, followed by GLC analysis of the ozonolysis fragments. During the hydrogenation process, re-sidual ethylenic bonds in the 20:2 isomers tend to migrate both towards the carboxyl group and towards the methyl end of the molecule. The hydrazine reaction results revealed that thetrans ethylenic bonds in the 20:2 and 20:3 isomers were distributed all along the the carbon chain, but thecis ethylenic bonds were more localized in the Δ11,Δ14 and Δ17 positions of the preexisting major menhaden oil component 20:5Δ5,8,11,14,17. Iatroscan analyses on AgNO₃-chromarods revealed that, as a result of the hydrogenation process, almost half of the 20:2 isomers were non-methylene-interruptedcis, trans/trans, cis structures. Presented in part at the 73rd annual AOCS meeting, Toronto, 1982.     

Palm Oil Products - Why and How to Use them

Palm oil is a very versatile oil. Its techno-economic strength is based on the following factors: 1. It is often cheaper than soyabean oil; 2. it can be used as a major component of consistent or solid fats without hydrogenation; 3. Malaysian refined palm oil requires only little reprocessing before use; 4. Palm oil possesses specific properties of value. It imparts Beta prime crystallinity on blends. It has great stability at frying temperatures. It contains no trans double bonds. A palm mid-fraction is highly compatible with cocoabutter. A number of specific food applications and formulae are discussed. Soap is the largest technical use of fats. Palm stearin is competitive with tallow in price, and may offer cost savings because it requires less clean-up for soap manufacture.     

Geometrical and positional isomerization of alkenyl acetates produced by hydrogenation of alkynyl acetates over palladium metal catalysts

Alkenyl acetates containing both geometrical isomers can be produced by a single controlled catalytic hydrogenation of the corresponding alkynyl acetate. The hydrogenation is capable of yielding formulations containing up to 60% trans isomer; the reduction is attended by positional isomerization in both geometrical isomers.NRCC No. 16834.     

CLA formation in oils during hydrogenation process as affected by catalyst types,catalyst contents,hydrogen pressure,and oil species

The effects of types and amount of catalysts, hydrogen pressure, and kinds of vegetable oils on the formation of CLA isomers were studied during hydrogenation. CLA isomers were identified by using a silver ion-impregnated high-performance liquid chromatograph and 100-m cyano-capillary column gas chromatograph. A selective catalyst (SP-7) produced a considerably higher content of CLA in soybean oil than nonselective catalysts. The maximal quantity of CLA produced in soybean oil during hydrogenation increased greatly with increasing amount of catalyst. By increasing the amount of selective catalyst from 0.05 to 0.3%, the quantity of total CLA obtained was about 1.9 times higher. Changes in hydrogen pressure also greatly influenced total CLA formed. By decreasing hydrogen pressure from 0.24 to 0.024 MPa, the quantity of CLA obtained was about 1.3 times higher. With different oil species (soybean, cottonseed, and corn oils), the time to reach the maximal quantity of CLA was different under the same hydrogenation conditions. However, the maximal quantity of CLA and proportion of CLA isomers formed were almost identical, regardless of oil species tested, under the same hydrogenation conditions.     

Continuous hydrogenation of fats and fatty acids at short contact times1

Continuous hydrogenation of fats and fatty acids using suspended catalysts was studied in a vertical flow reactor packed with Raschig rings. A short time of reactive contact of the fat or the fatty acid with the catalyst and hydrogen is the unique feature of this system. A nickel catalyst used in the hydrogenation of soybean oil gave a reduction of 40-50 iodine value units per min, small amounts oftrans-isorners (10-20%), large proportions of linoleate in unreduced octadecadienoyl moieties (70-80%), and nonselective reduction of polyunsaturated acyl moieties (linoleate selectivity ratio 1-3). Another nickel catalyst, used in the hydrogenation of tallow fatty acids, also gave a reduction of 40-50 iodine value units per min and nonselective reduction of polyunsaturated fatty acids. A copper chromite catalyst used in the hydrogenation of soybean oil gave a reduction of 10-15 iodine value units per min, low levels oftrans- isomers (10-15%), and selective reduction of linolenoyl moieties (linolenate selectivity ratio 4-6). Composition of positional isomers of cis- andtrans-octadecenoyl moieties in partially hydrogenated products obtained both with nickel and copper chromite catalysts reveals that essentially the same mechanisms of isomerization are involved in continuous hydrogenation at short time of reactive contact as in batch hydrogenation. 1The terms “linoloyl” and “linolenoyl” are used throughout to designate9-cis, 12-cis-octadecadienoyl and 9-cis, 12-cis, 15-cis- octadecatrienoyl groups, respectively.     

An evaluation of commercial nickel catalysts during hydrogenation of soybean oil

The activities of several commercial nickel catalysts were determined by measuring their activation energies. Among these catalysts, G95E, Resan 22, Nysosel 222 and 325, all with low activation energy, were more active than DM3 and G95H, which had higher activation energy. However, the less active catalysts increased the linoleate selectivity of soybean oil during hydrogenation. The yields of bothtrans isomers and winterized oil were higher for the more selectively hydrogenated oil catalyzed by the less active catalysts. In the sensory evaluation, the fractionated solid fat that contained moretrans isomers was lower in flavor scores than the fractionated liquid oil after hydrogenation and winterization of soybean oil.     

The use of bleaching earth in fatty acid production

Pretreatment of crude tallow or fish oil fatty acids with bleaching clays considerably improves the rate of hydrogenation with several different catalysts. Several series of tests were run to demonstrate these effects, and the data are presented.     

Influence of Various Reaction Parameters on the Reactivities of Highly Unsaturated Fatty Acids During a Partial Hydrogenation on Nickel Catalyst and on the Formation of Isomeric Mono- and Di-Ethylenic Acids

A refined menhaden oil of iodine value (IV) of 189 was hydrogenated on nickel catalyst under different temperatures, rates of agitation, hydrogen pressures and nickel content. Samples were collected during each hydrogenation in order to calculate the selectivities of the different C₂₀ fatty acid classes (dienes, pentaenes). In each case, a large difference in reactivities was observed between the 20:1 and 20:2 acids, but the 20:3, 20:4 and 20:5 acids had similar behaviours toward the nickel catalyst. The reaction parameters had a great influence on the 20:2 selectivity. However they did not apparently affect the 20:3, 20:4 or 20:5 selectivity values. The 20:1 and 20:2 isomer distributions also depended on the reaction parameters. For the 20:1 acids, an accumulation of isomers with the ethylenic bonds close to the carboxyl group, especially cis Δ 5, trans Δ 5 and trans Δ 6, was observed at high temperatures. The results can be interpreted as the combination of a substantial migration of ethylenic bonds and simultaneously a preferential hydrogenation of those ethylenic bonds farthest removed from the carboxyl group.     

Industrial hydrogenation of rice bran oil,a substitute for tallow

The Indian soap industry’s hard fat requirement was met until recent years by imported animal tallows. The search for alternate hard fats, consequent to the ban on the import of animal tallows in 1983, led to realization of the striking similarity in the fatty acid composition of mutton tallow and hydrogenated rice bran oil, except for thetrans oleic acid content. This paper traces the course of compositional changes undergone by rice bran oil during industrial hydrogenation, employing gas liquid chromatography and infra red spectroscopy.     

Influence of Cationic Surfactants on the Crystallization of Cis‐ and Trans‐Isomers

The crystals of cis‐ and trans‐isomers present in principle similar chemical groups on their respective crystal faces. Here, the crystallization of cis‐ and trans‐isomers (maleic acid and fumaric acid) in an aqueous solution containing cationic surfactants with different hydrophobic chains (the long hydrophobic chains of dodecyltrimethylammonium bromide < cetyltrimethylammonium bromide < trimethylstearylammonium bromide) was investigated. Results showed that the surfactants presented different effects on the crystallization of cis‐ and trans‐isomers. For trans‐isomers (fumaric acid), the surfactants with longer hydrophobic chains or higher solution concentrations will favor a wider metastable zone width (MZW) and a greater morphology change. By contrast, both the MZW and morphology development of cis‐isomers (maleic acid) were not affected by these surfactants. The chemical groups on crystal faces, surface grooves, and molecular polarity were compared to reveal the different influences of surfactants on the crystallization of cis‐ and trans‐isomers.     

Margarine's trans-fatty acid composition: modifications during the last decades and new trends

Trans fatty acids isomers are formed during the hydrogenation process used in the food industry to harden oils. In the last decades there has been a great controversy about the consumption of margarine due to the levels of trans fatty acids they contain. While in the eighties consumption of margarines was considered healthy, during the nineties several studies indicated that consumption of 18:1t increased LDL-cholesterol levels and decreased HDL-cholesterol level, and was related with an increased risk of coronary heart disease. The publicity about the unfavourable effects of trans fatty acid consumption seems to have influenced margarine producers to reduce the trans fatty acid content of margarines. Meanwhile USA has adopted a new legislation about trans fatty acid labelling. In Europe, Dinamarca has limited the maximum level of trans fatty acids allowed in food products.     

A study of the flavor stability and autoxidation of beef fats

Summary The odoriferous compounds isolated from a fresh edible tallow were found to be very complex in nature and could not be diminished by treatment with carbonyl reagents. When these compounds were removed by deodorization, the bland tallow which was obtained developed on autoxidation another type of odoriferous compounds. The latter contained various carbonyl compounds of the type which have been associated with flavor reversion in edible oils. The characteristic odor of oleo oil and edible tallow could be removed by slight hydrogenation of high selectivity under atmospheric pressure. This hydrogenation process raised the melting point by less than 2°C. but substantially decreased the linolenic and arachiidonic acid content. The hydrogenated products, after deodorization, were not only bland in odor and flavor but also had flavor stabilities better than those of some of the best commercial shortenings. Funds for this study were furnished by a grant-in-aid from Swift and Company, Chicago, Ill. Presented at the American Oil Chemists’ Society meeting, Minneapolis, Minn., October 11–14, 1954.     

Displacement of the double bonds during hydrogenation of unsaturated fatty acid methyl esters

Summary The displacement of the double bond of several unsaturated fatty acid methyl esters during hydrogenation with a nickel-kieselguhr catalyst at 180°C. was investigated. The analysis of the dicarboxylic acids (obtained by oxidation of the reaction products with KMnO₄ in acetic acid solution) by means of partition chromatography enabled a reliable semiquantitative determination of the position isomers formed. During hydrogenation of methyl esters of oleic, elaidic, petroselinic, and linoleic acid formation of large amounts of position isomers was proved to occur. Migration of the double bonds in both directions took place but was in all cases strongly pronounced in a direction opposite the ester group. The place and configuration (cis or trans) of the double bonds in the starting material apparently were of little importance in this respect. It follows that hydrogenation of fatty acid esters leads to products which are far more complicated, as is generally known. This is especially of importance with respect to the application of hydrogenated fatty oils in the food industries.     

Effect of the presence of sulfur during the hydrogenation of canola oil

Sulfur was added to refined and bleached canola oil before hydrogenation in the form of allyl isothiocyanate and the effects on hydrogenation rate and fatty acid composition were determined. The effect was more pronounced under selective conditions (200 C and 7 psi) than under nonselective conditions (160 C and 44 psi). Sulfur added at the level of 3 mg/kg under selective conditions stopped the hydrogenation at an iodine value (IV) of 81, with 5 mg/kg at IV 88. Under nonselective conditions, there was a decrease in reaction rate, but even with 10 mg/kg added S, the reaction could be made to reach IV 70. The amount of S bound to the commercial nickel catalyst was determined and in all cases was less than the amount that was bound to Raney nickel. Relatively more sulfur was bound at lower temperature (longer time) and higher pressure. Addition of 3 mg/kg of S or more resulted in considerably higher formation of trans isomers.     

Processing for industrial fatty acids - II

Fatty acids are produced industrially from tallow, palm oil, palm stearin, palm kernel oil and coconut oil. The current and future supply situations of these raw materials and market economics favor palm stearin and palm kernel oil as major raw materials for fatty acids. The Malaysian oleochemical industry has adopted high-temperature and high-pressure “splitting” of triglycerides. Variations in product yields occurring in the processing of tallow and palm stearin and of coconut oil and palm kernel oil are indicated. Developments on the enzymic hydrolysis of triglycerides to fatty acids have been made, particularly in Japan. Enzymic hydrolysis at low temperature has the advantage of energy conservation compared to the high-temperature and pressure-splitting process. But enzymic hydrolysis is only applicable to triglycerides of low titre, such as palm kernel oil.     

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

Directed 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     

Changes with diet in the composition of phosphatidyl choline of sheep bile

Bile phosphatidyl choline from sheep, in contrast to that from nonruminants, contains low levels of the normal range of polyunsaturated fatty acids. A comparison has been made of the composition of bile phosphatidyl cholines from sheep receiving either a control diet, a control diet supplemented with unprotected maize oil, or a control diet supplemented with soybean oil or tallow that had been protected against hydrolysis and hydrogenation of the rumen. The composition of bile phosphatidyl choline from sheep receiving protected soybean oil supplement was virtually indistinguishable from that from nonruminants.     

Selective hydrogenation of the cyclopropene acid groups in cottonseed oil

The cyclopropene acid groups in cottonseed oil can be modified by a light hydrogenation which will not produce large amounts oftrans isomers or lower the iodine value to a significant extent. Optimum conditions, as indicated by this investigation, are 105-115C, 20 psig hydrogen pressure, 0.1% electrolytic nickel as catalyst, and a low hydrogen-dispersion rate. Under milder conditions of hydrogenation the elimination of the cyclopropenes was accompanied by a lower formation oftrans isomers and a lower hydrogenation of noncyclopropenes, but the time required increased. In one hydrogenation carried out with commercial nickel catalyst, the 0.4% of malvalic acid groups in the cottonseed oil was hydrogenated completely whereas the iodine value was reduced by only 1.7 units and only 2.1% oftrans isomers was formed. AVinterization of cottonseed oils which had been hydrogenated to the point of eliminating their response to the Halphen test and in which only small amounts of saturated acid groups andtrans isomers had been formed gave yields equal to or better than those of the original oil. Hydrogénation actually increased the ease of winterization. 2 So. Utiliz. Ees. Dev. Div, ARS, USDA.