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.     

Supported gold catalysis in the hydrogenation of canola oil

The catalytic activity of gold supported on silica orγ-alumina has been studied in the hydrogenation of canola oil. In the hydrogenation of butadiene and pentene using these catalysts, high stability, low yield oftrans-isomers and high monoene selectivity have been reported in the literature. Catalysts containing 1% and 5% Au w/w on porous silica andγ-alumina were active in hydrogenating canola oil in the range of 150 to 250 C and 3550 to 5620 kPa. The activity level of these catalysts was about 30 times lower than that shown by the standard AOCS Ni catalyst based on the concentration of metal (g Au/L oil). Up to 91% monoene content was obtained using these catalysts in comparison with a maximum of 73% for the AOCS standard Ni catalysts. Gold catalysts can be recovered easily by filtration and reused several times without a decrease in activity. The hydrogenated oil was nearly colorless. No gold was detectable in the oil. Contrary to claims in the patent literature, the gold catalyst produces higher concentrations oftrans-isomers than does nickel. However, using gold catalysts the complete reduction of linolenic acid in canola oil can be achieved at a lowertrans-isomer content in the products than that obtained by using the AOCS standard nickel catalyst.     

Heterogeneous catalytic hydrogenation of canola oil using palladium

The hydrogenation of canola oil was studied using palladium black as a potential catalyst for producing partially hydrogenated fats with lowtrans-isomer content. Pressure (150\s-750 psig) appeared to have the largest effect ontrans-isomer formation. At 750 psig, 90 C and 560 ppm metal concentration, a maximum of 18.7%trans isomers was obtained at IV 53. A nickel catalyst produces about 50%rans isomers at the same IV. For palladium black, the linolenate and linoleate selectivities were 1.2 and 2.7, respectively. The maximum level oftrans isomers observed ranged from 18.7% to 42.8% (150 psig). Temperature (30\s-90 C) and catalyst concentration (80\s-560 ppm) affected the reaction rate with little effect ontrans-isomer formation and selectivities. At 250 psig and 50 C, supported palladium (5% Pd/C) appeared to be twice as active as palladium black. At 560 ppm Pd, 5% Pd/C produced 30.2%trans (IV 67.5), versus 19.0%trans for palladium black (IV 68.9). Respective linoleate selectivities were 15 and 6.6, while linolenate selectivities were approximately unity. Analysis of the oil samples by neutron activation showedapproximately a 1 ppm, Pdresidue after filtration.     

Electrochemical hydrogenation of canola oil using a hydrogen transfer agent

A novel low-temperature process for the electrochemical hydrogenation of canola oil is described. An emulsion of oil and water containing formic acid and a nickel hydrogenation catalyst, placed in the cathode compartment of an electrolysis cell and subjected to an electrical current, underwent hydrogenation at temperatures as low as 45°C. At these low temperatures of hydrogenation, the trans FA content of the hydrogenated canola oil was very low as compared with that of the edible oils hydrogenated by commercial processes using high temperature and high partial pressure of hydrogen gas. Because of its adverse health effects, a high trans FA content in edbile oils is viewed as undesirable. In addition to the commercially available nickel supported on silica, amorphous nickelphosphorus alloys supported on a variety of substrates were also used. Amorphous alloys are generally very corrosion resistant because of the absence of grain boundaries. A mechanism for hydrogenation using the hydrogen transfer agent of formic acid and its continuous regeneration at the cathode was evoked to explain the experimental data.     

Homogeneous catalytic hydrogenation of canola oil using a ruthenium catalyst

Dichlorodicarbonylbis (triphenylphosphine) ruthenium (II), RuCl₂ (CO)₂ (PPh₃)₂, was investigated as a catalyst for edible oil hydrogenation in a preliminary screening of potential catalysts for producing partially hydrogenated fats with lowtrans-isomer content. Refined, bleached and deodorized canola oil was hydrogenated using 1.77 × 10⁻⁵ − 6.64 × 10⁻⁴ mol/kg-oil of ruthenium catalyst equivalent to 1.79 × 10⁻⁴ − 6.71 × 10⁻³ wt% Ru. The effects of temperature (50–180 C) and pressure (50–750 psig) on reaction rate,trans-isomer content and fatty acid composition were examined. The activities of RuCl₂ (CO)₂ (PPh₃)₂ and nickel (Nysel HK-4 and AOCS standard nickel catalyst) were compared on a molar basis. At 4.40 × 10⁻⁴ mol/kg-oil (0.0026 wt/Ni or 0.0044 wt% Ru), 140 C and 50 psig, the nickel catalysts were completely inactive, but the ruthenium catalyst produced an IV drop of 40 units in 60 min. At 110 C, 750 psig and 1.34 × 10⁻⁴ mol/kg-oil (1.35 × 10⁻³ wt% Ru), a hydrogenation rate of 0.89 ΔIV/min and a maximumtrans-isomer content of 10.4% (IV=45.0) was obtained with the ruthenium catalyst.     

Trisaturates in the hydrogenation of canola oil with a commercial nickel catalyst

Refined and bleached Canola oil was hydrogenated with Pricat 9906 catalyst to an iodine value of 65 using various temperatures, pressures and catalyst concentrations. Hydrogenation with this catalyst resulted in great differences in SFI curves of fats with the same IV. Hydrogenation rate, dropping point, trisaturate content and linoleate selectivity were determined. All of the oils hydrogenated to IV 65 contained almost the same amount of solid fat at 20 C. For this reason, the crystal structure of the fats was examined by X-ray diffraction at 20 C. The catalyst was found to be non-selective. Increased selectivity can be obtained by careful temperature and pressure control. Reactivity also is temperature and pressure dependent. High trisaturate content increased instability by promoting formation of β crystals. The catalyst had excellent filterability characteristics.     

Reactivity of fatty acids in the different positions of the triglycerides during hydrogenation of canola oil

Canola oil was hydrogenated under selective and nonselective conditions. After various hydrogenation times, the triglycerides were hydrolyzed by pancreatic lipase and the monoglycerides separated by TLC. Triglycerides and monoglycerides were analyzed for fatty acid composition andtrans isomer content. The reaction rate in the 2- and 1,3-positions of the glycerides was identical and of first order kinetics. Since the 2-position of the canola oil contained higher levels of 18:2 acids, the rate of change was greater than in the 1,3-positions. There were indications of a slightly lower rate oftrans formation in the 2-position during nonselective hydrogenation. Linoleate selectivities for the 2- and 1,3-positions were determined.     

Effect of mixed alcohol reactants on ultrasonic alcoholysis of canola oil

The effect of ultrasonic irradiation energy was analyzed according to the kinds of alcohol in the ultrasonic alcoholysis. The ultrasonic irradiation energy density of ethanol (792.9 kJ/L) is higher than methanol (649.8 kJ/L). The optimum mixing ratio of canola oil, methanol and ethanol was proven as 1, 5 and 1, respectively. Also the optimum reaction conditions for the ultrasonic alcoholysis were a reaction temperature of 60 °C, ultrasonic irradiation power of 500 W, reaction time of 50 min, and alkaline catalyst (KOH) content of 0.6 wt.%. From these results, the optimum alcohol mixing ratio and the optimum process conditions were determined, with good quality biodiesel being manufactured.     

Effect of genetic modification on the distribution of minor constituents in canola oil

Oil derived from different lines of genetically modified canola varieties was analyzed for phospholipids, tocopherols, and phytosterols by various chromatographic techniques. As observed previously in genetically modified soybean oils, there was a decrease in the content and composition of phosphatidic acid in three of the modified canola oils derived from the 12 varieties investigated. Normal-phase high-performance liquid chromatographic (HPLC) analyses showed small variations in the phospholipid content of major classes, despite few differences in their composition. Reversed-phase HPLC data indicated that the molecular species distribution of phosphatidylethanolamine was significantly altered by genetic modification when compared to phosphatidylcholine. Impact of oilseed modification on the tocopherol content was variable, with greater variation in the concentration of α- and γ-tocopherols than δ-tocopherol. Phytosterol composition was markedly affected by genetic modification. Brassicasterol, campesterol, and β-sitosterol levels were consistently lowered in one genotype, whereas increased brassicasterol content was observed in the other variety. In general, genetic modification of canola seeds led to changes in the distribution of phospholipids, tocopherols, and phytosterols. Presented in part at the 89th AOCS Annual Meeting & Expo, Chicago, Illinois, May 10–13, 1998.     

Effect of sprouting on the quality and composition of canola seed and oil

Sprouting has been considered as a damage factor in grading canola. This project deals with the evaluation of the effect of sprouting on the quality and composition of canola seed and oil. Sprouted seeds had lower oil content than nonsprouted seeds as determined by exhaustive petroleum ether extraction. The difference, although statistically significant, was small, less than 0.1% oil at the maximum level of sprouting allowed in topgrade canola. There were no differences in chlorophyll contents or moisture contents between sound and sprouted seeds. Sprouted seeds had significantly higher levels of FFA and crude protein than sound seeds. Oxidation parameters (diene and aldehyde) were higher in oils from sound seeds than oils from sprouted seeds, but there was no statistically significant difference in PV. Sprouted seeds had higher levels of tocopherols and sucrose, but lower levels of raffinose, stachyose, and total sugars than sound seeds. There was no difference in overall FA composition of the oil between sound and sprouted seeds. The second extraction of the Federation of Oils Seeds and Fat Associations (FOSFA) extraction method, which allowed the extraction of more polar lipids, contained significantly more saturated FA. However, this was not significant in the overall FA composition of the oils because this fraction counted for about 2% of the total lipid content. The presence of sprouted seed had an effect on results for oil and crude protein determined by NIR as compared with results by FOSFA extraction, or pulsed NMR for oil and Dumas combustion for crude protein. Addition of sprouted seed samples to the NIR, calibration set overcame this problem. These results suggested that sprouting did not have a highly damaging effect on the quality and composition of canola seed and oil when less than 10% of the seeds in a sample were sprouting.     

Effect of agitation on selectivity in the hydrogenation of soybean oil

Summary A total of 12 hydrogenations were conducted in the pilot plant. The conditions were such that analyses of the data would furnish information as to the effect of 6 variables on the course of the reaction. The most reliable estimates were obtained for the effect of increasing, by agitation, the dispersion of hydrogen in the oil. The dispersion was accomplished by converting from a simple turbine agitator to a gas dispersing type with easily fabricated parts. This change resulted in a more selective reaction with respect to unsaturates. The change can also result in a shorter reaction time, or in the consumption of less power. Judging from its effects on the course of hydrogenation, agitation cannot simply be defined in terms of speed. Presented at AOCS Press meeting, San Antonio, Tex., Apr. 12–14, 1954. One of the Branches of the Agricultural Research Service, U. S. Department of Agriculture.     

Effect of agitation in the hydrogenation of castor oil

Castor oil was hydrogenated to evaluate the effect of agitation during hydrogenation. The turbine and propeller impellers were evaluated during hydrogenation of castor oil at various temperatures, pressures, and catalyst concentrations. The effect of impeller position in the agitator at definite oil depth was also evaluated. Hydrogenation of castor oil at 130°C, 2.0 kg/cm² hydrogen gas pressure with 0.5% Ni catalyst for 6 h while using two turbine impellers fitted in an agitator, one close to the reactor bottom and another at a height just below the top oil layer, revolving at 350 rpm, resulted in a product of a iodine value of 4.1, hydroxyl value of 156.4, and slip point of 84°C.     

Rapid extraction of canola oil

The simultaneous size reduction and solvent extraction of canola seeds were studied using a laboratory blender and a small, pilot-scale Szego mill. The laboratory tests established that over 95% of the oil may be removed from the seed in a single contact stage. The effects of contact time and solvent-to-seed ratio were investigated. The extraction equilibrium favored the extraction of the oil at higher solvent-to-seed ratios. In all cases the extraction reached some 90% of the equilibrium value after 3 min. Runs in the Szego mill, which is a unique orbitalmill developed by one of us (O. Trass), confirmed that solvent grinding is an efficient extraction technique. In this equipment, contact times as short as 30 sec give significant extraction, with the system approaching equilibrium in one minute. The Szego mill appears to be suitable for the rapid extraction of edible oil seeds such as rapeseed.     

Scale-up of canola oil degumming

The chemical degumming of canola oil was optimized using citric acid and maleic anhydride as degumming agents. These chemicals were selected from a group of 54 degumming agents, reported previously. The effect of temperature, chemical addition level, water addition level and contact times was investigated. Best results were obtained at 40 C, using 10 min contact with the chemical, followed by the addition of 2% water and agitation for 20 min. Chemical degumming reduced the residual phosphorus level from 1049 mg/kg to 50 mg/kg using either maleic anhydride or citric acid. Refining tests gave excellent deodorized or hydrogenated products. The optimized reaction conditions were applied to 330 kg test batches of oil in the P.O.S. Pilot Plant. Results were identical to those obtained in the laboratory, indicating that the process may be scaled up readily for industrial application.     

Polymorphism of hydrogenated canola oil

The polymorphism of hydrogenated Canola oil was investigated using X-ray diffraction. The effects of hydrogenation conditions (selective: 200 C; 48 kPa hydrogen pressure, and nonselective: 160 C; 303 kPa) and degree of unsaturation on the transformation β′ → β are discussed. A densitometer was used to follow the changes in the relative density of the characteristic short spacings, in an attempt to present a semiquantitative measure of β′ « β transformation during storage. The samples studied were selectively and nonselectively hydrogenated Canola oils of iodine values (IV) 70 and 60, respectively. Among the 4 samples, the selectively hydrogenated sample with IV 70 was the most stable and the nonselectively hydrogenated sample with IV 60 the least stable.     

Effect of hydrogenation on density and viscosity of sunflowerseed oil

The densities and viscosities of unhydrogenated and hydrogenated sunflowerseed oils have been determined at temperatures ranging from 25 to 50°C at 5°C intervals. The densities of these oils vary linearly with temperature. The values of the parameters for the density equation have been calculated. Smooth curves were obtained when the changes in viscosity with temperature were plotted in the form of ln η vs. 1/T. The energy of activation, the free energy of activation, and the entropy of activation have been calculated at 25°C, and they decreased with the degree of unsaturation in the fatty acid chains of the sunflowerseed oil.     

Catalytic hydrogenation of soybean oil methyl esters and some related compounds

Mixtures of platinum complexes and tin(II) chloride are effective homogeneous catalysts for the hydrogenation of soybean oil methyl ester, reducing it to the monoene stage only. Hydrogenation and isomerization reactions have been examined under various conditions, using a solvent consisting of 60% benzene and 40% methanol. The extent of hydrogenation depends upon the temperature (90C>60C>30C) but not upon the pressure (1075 psi as compared with 525 psi). It almost stops after 3 hr, although one double bond remains in the molecule. After hydrogenation with a catalyst consisting of a mixture of dichloro-bis-triphenylphosphine-platinum(II) and tin(II) chloride, soybean oil methyl ester shows an increase in monoene, a decrease in diene and triene, and formation of conjugatedcis-trans andtrans-trans dienes, but no increase in stearate. Similarly, methyl oleate and methyl linoleate were converted to trans monoene, but not to stearate. Hydrogenations with mixtures of tetrachloroplatinum(II) ion or hexachloro-platinum(IV) ion and tin(II) chloride were similar to those described above but they form some stearate. Several other metal ions were studied as replacements for tin. None of them were effective.     

Effect of baicalein and acetone extract of Scutellaria baicalensis on canola oil oxidation

There is an increasing interest in natural antioxidants present in traditional Chinese herbal medicines. The present study examined the antioxidant activity of heane, acetone, and methanol extracts, as well as baicalein purified from the dry roots of Scutellaria baicalensis Georgi (common name: Huangqin), in heated canola oil. Oxygen consumption and decreases in linoleic acid linolenic acid content were monitored in canola oil held at 90–93°C. Among the three extracts, the acetone extract was most effective against oxidation of canola oil, followed by the methanol extract of the dry roots. The antioxidant activity of these three extracts correlated well with their content of baicalein, which provided strong protection to canola oil from oxidation. The antioxidant activity of Huangqin acetone extract was dose-dependent. The acetone extract at 100 ppm or above was even more effective than butylated hydroxytoluene at 200 ppm in protecting canola oil from oxidation. The present results suggest that the acetone extract of these roots should be further explored as a potential source of natural antioxidants for use in the processed foods.