Coulometrische Schnellmethode zur Bestimmung der Hydrierjodzahl

A Rapid Coulometric Method for the Determination of Iodine Value by Hydrogen Uptake A rapid method for the determination of degree of unsaturation of oils and fats is of importance for the oil and fat industry. In addition to the common methods for the determination of iodine value, alternative methods, based on hydrogenation, are available. In the methods involving hydrogenation of the oil or fat, as described in the literature, hydrogen is either externally added to the system or generated internally by chemical means, such as, by the addition of a standardized sodium boronate solution to the reaction mixture. The authors have mechanized the hydrogenation by generating hydrogen chemically using an electrolytic method in a special coulometric system which excludes the titration step. The iodine value of an oil or fat can be calculated from the current consumed according to Faraday's law. The sample, without prior treatment, is injected and hydrogenated within 2-3 minutes. More than 100 samples can be injected into the same reaction mixture. This method is more exact than the common procedures, because only an addition of hydrogen to the double bonds but no substitution occurs. The iodine values, determined for fats and oils within a range of values between 10 to 190, agree well with the values determined according to Wijs' method. The standard deviation is less than 1%.     

Measurement of the consistency of plastic vegetable fats

Summary 1. An improved micropenetrometer is described, by means of which it is possible to measure the consistency of fats with a high degree of precision. 2. The intelligent use of a micropenetration method requires some consideration of the theory of plasticity in fats. This theory is briefly discussed. 3. The influence of various factors on the consistency of solidified fats has been investigated, and as a result of this investigation a standard technique for making micropenetration tests is proposed. 4. Micropenetration data are recorded on cottonseed, peanut, and soybean oils hydrogenated to different degrees, on cottonseed oil blended with various proportions of highly hydrogenated oil, and on various commercial samples of shortening and margarine. 5. A quick micropenetration method, applicable as a control in the hydrogenation of fat products, is described.     

Selektive Härtung von Fetten und Fettsäuren mit Sulfiden der Übergangsmetalle als Katalysatoren

Selective Hydrogenation of Fats and Fatty Acids with Sulfides of Transition Metals as Catalysts Sulfides of some transition metals are suitable as catalysts for the selective hydrogenation of fats and fatty acids. Ni₃S₂, a stoichiometrically, thermally and crystallographically defined compound is especially active. Also mixed catalysts containing tungsten sulfide and molybdenum sulfide besides Ni₃S₂ are sufficiently active. The same is true for cobalt sulfide catalysts, whereas molybdenum sulfide and tungsten sulfide exhibit considerably lower activities. The conditions of hydrogenation are essentially the same as customary: temperature range 180° to 210°C for fats, 200° to 220°C for fatty acids, hydrogen pressure 2–25 kg/cm², catalyst concentration 0.05 to 2 parts by weight of metal sulfide per 100 parts of fat or 0.5–5 parts by weight of metal sulfide per 100 parts of fatty acids. Using the above catalysts, the selectivity of S₃₁ or S₂₁ attained in the steps triene (polyene → monoene or diene → monoene is over 75. The remaining double bonds in the hydrogenated product possess almost exclusively the trans configuration. The above catalysts are resistant to sulfur compounds and they exhibit exceptional longevity. The regeneration can be performed with ease. Consequently, the pretreatment of the material to be hydrogenated can be limited to washing and drying.     

Hydrogenation of fatty acids

Catalytic hydrogenation is a vital process for both the edible fats and oil and the industrial fatty chemical industries. The similarities and differences between the fat and oil and fatty acid hydrogenations in equipment, processing conditions, and catalysts employed are of some importance since both are used in the various operations. Generally, the catalytic hydrogenation of fatty acids is carried out in corrosion-resistant equipment (316SS), whereas for fats and oils while 316SS is desirable, 304SS or even black iron surffice. The speed of hydrogenation varies radically with the content of impurities in both fat and oil and fatty acid feedstocks. Especially detrimental for both hydrogenations are soap and sulfur contaminants, proteinaceous materials left in the oils from poor refining, etc. Fatty acids from vegetable oil soapstocks are especially difficult to hydrogenate. Soybean-acidulated soapstock must usually be double-distilled for good results; cottonseed soapstocks frequently triple-distilled in order that they can be hydrogenated below iodine values of 1. Fatty acid hydrogenation effectiveness is measured by achieveing a low iodine value as fast and as economically as possible. Variables that influence hydrogenation effectiveness are reactor design, hydrogen purity, feedstock quality, catalyst activity and operating conditions.     

Nickel/Silber-Hydrierkatalysatoren und ihre Verwendung zur selektiven Härtung von Fetten

Nickel/Silver Catalysts and Their Application in Selective Hydrogenation of Fats Catalysts used for the hardening of fats are critically evaluated from the view-point of reaction mechanisms and kine-tics. Carrier catalysts composed of nickel and silver exhibit high selectivities, low rates of isomerization and unusual longevity. They can be removed completely from the hydrogenated fat by the usual operations. These catalysts, which do not have the drawbacks of copper-containing catalysts, can be used instead of the latter. Hydrogenation characteristics of the new catalysts depend upon their composition and mode of preparation. Two types of nickel/silver catalysts have been found suitable; Ni/Ag-carrier catalyst TR containing at least 10 parts of silver per 100 parts of nickel, which is reduced at 220°–290°C, and Ni/Ag-carrier catalyst HS containing 7 to 8 parts of silver per 100 parts of nickel, which is reduced at 350°–450°C. Both catalysts TR and HS are suitable for the production of stable edible fats, for example, from soybean oil or rapeseed oils derived from the new varieties of rape. Using the type TR catalyst, the linolenic acid content of an oil can be reduced to a level of less than 2% without an appreciable reduction in the content of linoleic acid. Thus, from soybean oil, after removing small amounts of solid glycerides, a cold-stable salad oil can be obtained which does not tend to flavour reversion. The second type of catalyst, HS, reduces also the content of linoleic acid thus yielding heat-stable products that are suitable as frying oils and liquid shortenings. Experimental conditions and results of commercial testing are described. Methods for the preparation and handling of the new catalysts as well as the composition and the properties of hydrogenated products are presented.     

直馏柴油气-液相催化氧化脱硫研究

由于柴油加氢脱硫技术投资大、操作条件苛刻及污染严重等问题,氧化脱硫技术已成为研究热点。针对柴油H2O2氧化脱硫技术存在氧化剂价格高、柴油收率低和有含硫污水排放等技术经济问题,采用专用的柴油均相催化氧化脱硫催化剂TS-1和纯O₂氧化剂,在高压反应釜中对直馏柴油进行催化氧化脱硫,可达到很好的脱硫效果且耗氧量少。实验结果表明,在150 ℃、08 MPa、反应时间60 min和m(催化剂)∶m(柴油)=1 500 μg·g^-1的条件下,可将柴油硫含量从2 217.2 μg·g^-1降到265 μg·g^-1,脱硫柴油硫含量符合欧洲Ⅱ类柴油标准(≤300 μg·g^-1),柴油收率达到95.2%。     

Modification of karanja oil (Pongamia glabra) by fractionation,blending, and transesterification

In the present study the modification of detoxified and completely refined karanja oil (Pongamia glabra) was studied by physical and chemical means. Karanja oil was fractionated by the detergent fractionation process at low temperature (3 °C). Astearin fraction was obtained with a yield of 11.0 %. The stearin fraction as such or after bioacidolysis, was found to be suitable as margarine fat bases. Karanja oil was also blended with fats like palm stearin, vanaspati, hydrogenated rice bran oil, and hydrogenated soybean oil in various proportions. The blended products as such or after interesterification were found to be suitable as shortenings, margarine fat bases, or vanaspati substitute.     

柴油电催化加氢与氧化脱硫的系统集成

柴油中硫和多环芳烃含量要求越来越严,由于二苯并噻吩类硫化物的空间位阻导致传统的催化加氢难以实现以上目标。本文以泡沫铅为阴极,以石墨为阳极,在CH₃CN+EtOH+H₂O+Bu₄NBr电解体系中可以将柴油中多环芳烃的电解加氢和含硫化合物的电解氧化脱除集成。在该电解体系中泡沫铅电极上柴油电解加氢主要是温和的加氢,电解加氢后氢含量增加了1.1%,三环芳烃蒽类和菲类减少3.3%,但是总芳烃含量变化不大,十六烷值增加3.9。在石墨阳极上柴油中硫化物容易电解氧化,氧化产物砜类不能完全由电解体系萃取脱除,进一步通过活性炭吸附可以将柴油硫含量由884 μg·g^-1降低至44 μg·g^-1。     

Dilatometric investigations of fats II. Dilatometric behavior of some plastic fats between 0° C. and their melting points

Summary 1. Dilatometric curves between 0°C. and their melting points have been obtained for the following fats: lard, butterfat, cottonseed oil, peanut oil, a commercial margarine oil, a commercial all-hydrogenated vegetable shortening, three samples of soybean oil hydrogenated to different degrees, a hard butter fractionally crystallized from hydrogenated peanut oil, a mixture of tristearin and soybean oil, and a synthetic fat containing equal molar proportions of stearic and oleic acids. 2. The dilatometric curves, of volume change in the fat against temperature, were in every case composed of a series of straight lines, separated by sharp breaks or transition points. 3. The number of linear sections in the dilatometric curves corresponded in a general way with the known degree of complexity in the glycerides of the fats, and varied from two in the case of the relatively simple stearic-oleic glyceride mixture, to at least seven in the case of the all-hydrogenated shortening. Since each break in the curve must correspond to the disappearance of a distinct class of solid glycerides or glyceride complexes, the application of dilatometry to the qualitative and quantitative determination of glyceride composition in fats is suggested. 4. Only two of the fats examined, the mixture of tristearin and soybean oil, and the synthetic stearicoleic glyceride mixture, exhibited polymorphism, even after rapid solidification in ice water. Presented before the American Oil Chemists’ Society Meeting, New Orleans, Louisiana, May 10 to 12, 1944. This is one of four regional research laboratories operated by the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Detection of interesterified fat in hydrogenated fat by lipase hydrolysis and by cooling curve analysis

Porcine pancreatic lipase hydrolysis and Jensen’s cooling curve methods can be adopted for detecting interesterified fat products in a mixture with hydrogenated fats. Lipolysis of interesterified fats shows a relatively greater amount of saturated fatty acids in the 2-monoglycerides in comparison with hydrogenated fats. A similar trend of the distribution pattern of fatty acids also can be noted in a mixture. Interesterified fats do not show any rise in temperature in Jensen’s cooling curve experiment, whereas hydrogenated fats show a distinct rise in temperature. A gradual increase in temperature is obtained for an interesterified fat when it is mixed with increasing content of a hydrogenated fat. On the other hand, hydrogenated fat shows a lowering in the rise of temperature when it is mixed with an interesterified fat. Simultaneous determination of the fatty acid profiles of the 2-monoglycerides and Jensen’s cooling curve characteritics can be utilized in detecting the occurrence of one modified fat in another.     

Biological evaluation of hydrogenated rapeseed oil

A 91-day feeding study evaluated soybean oil, rapeseed oil, fully hydrogenated soybean oil, fully hydrogenated rapeseed oil, fully hydrogenated superglycerinated soybean oil and fully hydrogenated superglycerinated rapeseed oil at 7.5% of the diet in rats; a 16-wk feeding study evaluated soybean oil and the three rapeseed oils or fats at 15% of the diet. Each fat was fed to 40 rats as a mixture with soybean oil making up 20% of a semi-synthetic diet. No significant differences in body weight gains or diet-related pathology were seen in the 91-day study although the rats fed liquid rapeseed oil had slightly heavier hearts, kidneys and testes than the others. The rats fed the four fully hydrogenated fats ate more feed and had lower feed efficiencies than those fed oils but no differences were seen among the four hydrogenated fats. In the 16-wk feeding study, no pronounced pathology related to the diet was seen although the rats fed liquid rapeseed oil had a slightly higher incidence of histiocytic infiltration of cardiac muscle than the rats in the other groups. The female rats fed the three rapeseed oil fats gained significantly less weight and the females fed liquid rapeseed oil had enlarged hearts compared to the other groups. The absorbabilities of the six fats were measured in the 91-day study when fed as a mixture with soybean oil and as the sole source of dietary fat in a separate 15-day balance study. The four fully hydrogenated fats were poorly absorbed and the absorption of behenic acid from the two hydrogenated rapeseed oils was found to be 12% and 17% in the balance study and 8-40% in the feeding study. The adverse biological effects of unhydrogenated rapeseed oil containing erucic acid as reported in the literature do not occur with fully hydrogenated rapeseed oil. In addition, the low absorbability of the fully hydrogenated rapeseed oil is an added factor in its biological inertness.     

Detection of interesterified fats in hydrogenated fats

Interesterification of fats is being used increasingly as an alternative to hydrogenation in preparing shortening and margarine bases. The detection of interesterified fats in vanaspati (a hydrogenated fat) is relevant because of possible adulteration problems. Either palmitic acid-rich or stearic acid-rich interesterified fats were blended with 13 market samples of hydrogenated fat (vanaspati) and examined by on-plate lipase hydrolysis of glycerides, gas chromatographic determination of fatty acids of the isolated 2-monoglycerides and calculation of two emperical indices. These were R₁, the ratio of the amounts of palmitic acid present in the 2-position to that in the total glyceride, and R₂, the ratio of saturated acid present in the 2-position to total saturated fatty acid in the fat. The vanaspati, R₁ was always below 10 and R₂ was always below 20. The presence of 5–10% interesterified fat raised both figures and offered a suitable basis for the detection of interesterified fats in hydrogenated fats.     

煤基石脑油加氢研究

采用三段加氢工艺对煤基石脑油进行了加氢处理,重点研究了反应温度、压力、空速对一段加氢效果的影响,并对该段催化剂的使用寿命进行了考查,初步探讨了三段加氢反应温度对加氢性能的影响。研究结果表明经过三段加氢后的产品溴值小于1.0 g Br/100 g,总硫小于0.5μg/g,可用于汽油调和组分、芳烃抽提或环保溶剂油。     

Nutritional effects of hydrogenated soya oil

Soybean oil is the leading edible vegetable oil in the world in terms of volume, and considerable amounts are consumed in partially hydrogenated forms. Early recognition that commercial hydrogenation of vegetable fats produces isomeric forms of monoenes and polyunsaturates has prompted much research and speculation on the nutritional properties of hydrogenated fats, including soya oil. Past results of studies with animals and humans will be reviewed and key findings will be summarized and discussed. Particular attention will be devoted to questions recently raised concerning the relationships of health and hydrogenated fats and an attempt will be made to put these matters into factual perspective in light of current knowledge.     

The Polymorphism of Low Erucic Rapeseed Oil with High Content of Palmitic Acid

A new type of low erucic acid rapeseed oil containing high amount (11%) of palmitic acid (C₁₆-LOBRA) was studied, both in labscale and in pilot-plant equipment. The polymorphic behaviour of fat blends and margarine emulsions consisting of C₁₆-LOBRA, LOBRA and soybean oil and their hydrogenated fats were examined. The results clearly show the potential in the hydrogenated C₁₆-LOBRA. The time before the stable ß-form is developed is much longer for the hydrogenated C₁₆-LOBRA compared with the hydrogenated LOBRA and in fact similar to a hydrogenated soybean oil. The hydrogenated C₁₆-LOBRA is therefore well suited to be used in e.g. margarine systems.     

水热处理对体相加氢催化剂活性的影响

体相催化剂经水热处理后,催化剂孔结构发生了改变,孔容、孔径和比表面积增加。采用小型加氢装置加工处理不同超深度脱硫难度的柴油原料,对水热处理后的催化剂进行超深度加氢脱硫活性评价。评价结果表明,体相催化剂经水热处理后,提高体相催化剂的超深度加氢脱硫活性和芳烃饱和性能,加工处理超深度脱硫难度大的劣质柴油时,加氢活性提高更加明显。以直馏柴油为原料,在相同工艺条件下,精制油中硫含量小于10μg/g时,对比没经水热处理的催化剂,水热处理后催化剂的反应温度降低了5℃。而以催化柴油为原料,在相同工艺条件下,精制油中硫含量小于10μg/g时,水热处理后催化剂的反应温度比水热处理前的反应温度降低了13℃。水热处理后的体相催化剂具有良好的活性稳定性。     

Electrochemical hydrogenation of edible oils in a solid polymer electrolyte reactor. Sensory and compositional characteristics of low Trans soybean oils

Soybean oils were hydrogenated either electrochemically with Pd at 50 or 60°C to iodine values (IV) of 104 and 90 or commercially with Ni to iodine values of 94 and 68. To determine the composition and sensory characteristics, oils were evaluated for triacylglycerol (TAG) structure, stereospecific analysis, fatty acids, solid fat index, and odor attributes in room odor tests. Trans fatty acid contents were 17 and 43.5% for the commercially hydrogenated oils and 9.8% for both electrochemically hydrogenated products. Compositional analysis of the oils showed higher levels of stearic and linoleic acids in the electrochemically hydrogenated oils and higher oleic acid levels in the chemically hydrogenated products. TAG analysis confirmed these findings. Monoenes were the predominant species in the commercial oils, whereas dienes and saturates were predominant components of the electrochemically processed samples. Free fatty acid values and peroxide values were low in electrochemically hydrogenated oils, indicating no problems from hydrolysis or oxidation during hydrogenation. The solid fat index profile of a 15∶85 blend of electrochemically hydrogenated soybean oil (IV=90) with a liquid soybean oil was equivalent to that of a commercial stick margarine. In room odor evaluations of oils heated at frying temperature (190°C), chemically hydrogenated soybean oils showed strong intensities of an undesirable characteristic hydrogenation aroma (waxy, sweet, flowery, fruity, and/or crayon-like odors). However, the electrochemically hydrogenated samples showed only weak intensities of this odor, indicating that the hydrogenation aroma/flavor would be much less detectable in foods fried in the electrochemically hydrogenated soybean oils than in chemically hydrogenated soybean oils. Electrochemical hydrogenation produced deodorized oils with lower levels of trans fatty acids, compositions suitable for margarines, and lower intensity levels of off-odors, including hydrogenation aroma, when heated to 190°C than did commercially hydrogenated oil.     

Tempering triglycerides by mechanical working

The tempering of fat products to convert their components to stable polymorphs is an important and a sometimes troublesome problem in the manufacture of these products, particularly chocolate and chocolate-type confections. It has been found that a solid-to-solid transformation to the stable polymorphs can be effected by mechanical working consisting of extrusion under pressure. With a fat of relatively few components, such as cocoa butter, evidence of the transformation can be obtained from X-ray diffraction patterns. For more complex fats, hardness and melting characteristics must be considered. There is evidence that mechanical working is also effective in the transformation of a cocoa butter-like fat made from hydrogenated cottonseed oil and olive oil, and in the transformation of highly hydrogenated cottonseed oil. Mechanical working to effect polymorphic transformation is also effective with products containing the fats mentioned. Presented at the 35th Fall Meeting of the American Oil Chemists' Society, Chicago, Illinois, October 30–November 1, 1961. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Palm oil and palm kernel oil in food products

Cocoa butter equivalent (CBE) formulation, especially the compatibility of palm oil based CBE with cocoa butter, is of special interest to chocolate manufacturers. Traditionally palm oil is fractionated to obtain high-melting stearin and olein with a clear point of around 25 C, the latter serving as cooking oil. Recently, palm oil has been fractionated to recover an intermediate fraction known as palm mid-fraction (PMF), which is suitable for CBE formulations. Generally, production of PMF is based on a three-step procedure. However, a dry fractionation system, which includes selective crystallization and removal of liquid olein by means of a hydraulic press, has been developed. Iodine value, solid content (SFI) at different temperatures, cooling curves (Shukoff 0°) and triglyceride/fatty acid composition determination confirmed effectiveness of the procedure followed. A direct relationship between yield, quality of PMF and crystallization temperature during fractionation has been achieved. Yield of 60% for olein of IV 64–67 has been achieved. Yield of 30% for PMF of IV 36–38 and 10% for high melting stearin of IV of 20–22 are also being achieved. High-melting stearin may be used in oleochemical applications, soaps, food emulsifiers and other industrial applications such as lubricating oil. Olein fraction, especially after flash hydrogenation thereby reducing the IV to 62/64, has excellent frying and cooking oil characteristics. Palm olein is also suitable as dietary fat and in infant formulation. Studies on interesterification of high-melting stearin with olein showed possibilities to formulate hardstocks for margarine and spread formulations, even without using hydrogenated fat components. Palm kernel and coconut fats or fractions or derived products are used for confectionery products as partial CB replacers and as ice cream fats and coatings. Coconut oil also serves as a starting material for the production of medium-chain triglycerides.     

Stationary catalysts for the continuous hydrogenation of fats

Hydrogenation characteristics of a wide variety of stationary catalysts were studied with an aim to explore their possible use in the continuous hydrogenation of fats. Refined soybean oil was hydrogenated continuously in a vertical flow-through reactor over a fixed bed of catalyst. Catalysts investigated were pelleted products containing Raney nickel, reduced nickel, reduced palladium, and copper chromite, as well as granulated alloys of the Raney type, such as Ni-Al, Cu-Al, Pd-Al, and Cu-Cr-Al, which were activated with alkali. These catalysts offered a wide choice of activity, selectivity, and ability to form geometrical isomers. Pelleted copper chromite and granular Raney copper-chromium were found to be highly selective toward the linolenate moiety of soybean oil, whereas pelleted palladium on carrier, as well as granular Raney nickel, Raney copper, and Raney palladium, though moderately selective, exhibited very high activity even at relatively low temperatures. A unique feature of most of the stationary catalysts was the remarkably high rate of hydrogenation. With most catalysts, the iodine value of soybean oil was reduced by 40–60 units within a reaction period of 2–4 min. The hydrogenated fat was practically free of catalyst particles.