Trans FA (TFA), solid fat contents (SFC), and slip melting points of 12 different tub and stick margarines marketed in Turkey were examined in this study. No trans isomers were found in four margarines, which suggests they were formulated from interesterified or blended fats and oils. The products with no TFA generally had more short‐chain saturated FA, which suggests coconut oil‐based oil components. TFA content of the other 10 products varied from 7.7 to 37.8%. Compared to the products formulated in North America, Turkish margarines contain more TFA and have higher SFC.

Soybean oil was hydrogenated using two different nickel-based commercial catalysts (Nysosel 222 and SP-10) at various ratios in 4-L reactors under constant conditions (165°C, 2 bar hydrogen pressure, and 500 rpm stirring rate). Trans isomer formation, reaction rates, selectivity (S) ratios, and melting behaviors of the samples were monitored during the reactions. When Nysosel 222 was used at 0.02, 0.03, and 0.04%, iodine values (IV) were reduced from 130.1 to 70.6, 50.9, and 44.7 and total trans isomers increased from 0 to 34.2, 43.3, and 40.5%, respectively, after 100 min of hydrogenation. However, SP-10 reduced IV from 130.1 to 77.2, 75.7, and 71.3 after 100 min when used at 0.1, 0.15, and 0.2%, respectively, whereas total trans isomers were 58.6, 70.4, and 70.7%. Reaction rates increased with catalyst ratio and time but were higher for Nysosel 222 than for SP-10 although 5-10 times less Nyosel 22 was used than SP-10. Linoleate selectivity (S 32 ) was almost constant for Nysosel 222, whereas it was higher but fell with time for SP-10. Increasing the catalyst ratio decreased the time needed to reach the highest oleate selectivity (S 21 ) ratios, and the IV values where the highest S 21 were attained were different for the catalysts. Increases in m.p. of SP-10 samples were slower after IV values of 80 were attained, where S 21 ratios reached to higher values. Solid fat contents (SFC) of these samples fell markedly above 21.1°C, and steeper SFC curves were obtained.Paper no. J11199 in JAOCS 82, 925-929 (December 2005).Hydrogenation reduces the relative unsaturation of oils and promotes geometric and positional isomerization (1). Formation of trans isomers affects the physical and chemical properties of the final products, as they have higher m.p. and greater stability than cis isomers (2). Since the late 1980s, hydrogenation has become less accepted in the formulation of food products because of the trans FA that form during the reaction. The main concern has been with trans-18:1 isomers. It has been shown that trans FA intake raises LDL cholesterol and lipoprotein (a) levels in blood, causing higher levels of coronary heart diseases and greater risks for artherosclerosis risks (3,4). Despite this, hydrogenation is still one of the most applied techniques in the fats and oils industry for producing a wide range of hardened fats with different melting properties. Hydrogenation, a catalytic reaction, involves the saturation of π-bonds of FA with hydrogen on a catalyst surface. Owing to the mechanism of the reaction, the rate of isomerization reactions is variable (5). The type of catalyst and its concentration in oil, the type of oil and its properties, the reaction temperature, hydrogen pressure, and stirring rate affect the concentration of hydrogen on the catalyst surface and thus change the course of the reaction. The choice of reactor type also can affect the reaction as a result of agitator design characteristics (6). Among these parameters, the type of catalyst and the concentrations applied are the most impo...

Experimentally determined viscosities of cottonseed, olive, hazelnut, corn, sunflower, canola and soybean oils were used in the development of an equation for simple and rapid viscosity estimation based on the fatty acid composition. The parameters A and B in the Andrade Equation were derived from the constants determined from each fatty acid using a computer program. The obtained equation was tested in the estimation of the viscosities of vegetable oils and their binary mixtures. Predicted and experimental viscosity values were then compared and average absolute deviations (AAD) calculated as 1.78% for vegetable oils and 3.48% for their mixtures. Due to the reasonable accuracy, this method could be applied to the common vegetable oils and their blends. This study also represents a model for their viscosity prediction of the oils having different fatty acid compositions.

Soybean oil was hydrogenated using two different palladium-based catalysts, 5% palladium on carbon (Pd/C) and 10% palladium on alumina (Pd/A), at various ratios in a 4-L reactor under constant conditions (165°C, 2 bar H 2 , and 500 rpm stirring rate). Reaction rate, trans isomer formation, selectivity ratios, and melting behaviors of the samples were monitored. Activity of Pd/C was about 10 times higher than that of Pd/A, and the reaction rate showed a strong dependency on the support material. Increases in the concentrations of both Pd catalysts did not have considerable effect on trans formation, which is slightly dependent on support material. Oleate selectivity (S 21 ) for all runs varied between 2.48 and 30.34, and type of support material did not have an effect on selectivity. Melting behaviors of the samples were mainly dependent on reaction rates.Industrial hydrogenation of fats and oils is usually catalyzed by nickel catalysts. The use of palladium catalysts is limited by their higher costs. Early reviews showed that palladium catalysts have greater selectivity and activity compared with nickel (1,2).Ahmad et al.(3) reported that catalyst with very high surface area (5% Pd/C) is less active than others at low temperatures, owing to metal deposition within catalyst pores that prevents easy access of molecules. This resistance is decreased at higher temperatures. They also reported that palladium produces more trans isomers than nickel at higher temperatures.Most of papers on the catalysis of oil hydrogenation consider studies based on Pd-catalyzed hydrogenations at lowered temperatures and elevated pressures to obtain less trans isomer content. Zajcew (4) hydrogenated a soybean oil/cottonseed oil mixture with 5% Pd/C catalyst at 120°C, under 45 psig H 2 pressure, at a reaction time of 100 min, the hydrogenated sample contained 35% trans FA at an iodine value (IV) of 71. Lowering the temperature decreased the trans fat content (5). The researcher also tested deactivated Pd/C catalyst for vegetable oil hydrogenation (6).Hsu et al. (7) examined four different Pd catalysts for canola oil hydrogenation at 50 ppm metal concentration, 70 and 90°C, and under 750 psig H 2 pressure. Pd/C was less active despite having the highest surface area. When this catalyst was used at 70°C, the trans isomer content of the sample with a 78.5 IV was 13%. The lowest trans content at the same conditions was achieved with an alumina-supported Pd catalyst.Ray (8) hydrogenated soybean oil at three different temperatures (27.6, 60, and 93°C) and pressures (5, 27.5, and 50 psig) using various metal concentrations of 5% Pd/C catalyst. Depending on the conditions, trans FA contents of the samples having about 65 IV varied from 38.0 to 57.7%. There was no advantage in using palladium with respect to trans formation or selectivity. Berben et al. (9) also reported that Pd catalyst did not give any benefits in reducing trans fat content when they examined 50 or 65 ppm palladium catalyst at 60°C and 102 psi for hydrogenation of soybean oil....

Effects of hydrogenation conditions (temperature, hydrogen pressure, stirring rate) on trans fatty acid formation, selectivity and melting behavior of fat were investigated. To this aim, soybean oil was hydrogenated under various conditions and fatty acid composition, trans isomer formation, slip melting point (SMP), solid fat content (SFC) and iodine number (IV) of the samples withdrawn at certain intervals of the reactions were monitored. A constant ratio (0.03%) of Nysosel 222 was used in the various combinations of temperature (150, 165 and 180 7C), stirring speed (500, 750 and 1000 rpm) and hydrogen pressure (1, 2 and 3 bar). Raising the temperature increased the formation of fatty acid isomers, whereas higher stirring rates decreased this formation, while changes in hydrogen pressure had no effect or slightly reduced it, depending on other parameters. Results also indicated that the trans fatty acid ratio increased with IV reduction, reached the highest value when the IV was about 70 and decreased at IV , 70 due to saturation. Selectivity values (S 21 ) at that point ranged between 5.78 and 11.59. Lower temperatures and higher stirring rates decreased not only the trans isomer content but also the S 21 values at significant levels. However, same effects were not observed with the changes in hydrogen pressure. It was determined that a high SMP does not necessarily mean a high SFC. Selective conditions produced samples with higher SFC but lower SMP, which is possibly because of higher trans isomer formation as well as lower saturation.