Vegetable oils: Effects of processing,storage and use on nutritional values

At the present time, vegetable oils are the source of most of the visible fat in the U.S. diet. They are used as salad and cooking oils, in salad dressing, margarine and shortening. Processing methods include extraction, refining, hydrogenation and interesterification. During storage and use, the products are exposed to oxygen and/or heat, particularly during frying. Processing, storage and use are related to changes in composition, nutritive value and physical characteristics of vegetable oils. Refining removes undesirable minor components present in crude oils. Refined polyunsaturated vegetable oils are the primary dietary source of tocopherols. Hydrogenation modifies physical characteristics and improves sensory and oxidative stability. This process converts some of the polyunsaturated fatty acids to new fatty acid isomers. Although the biochemical effects of these isomers are still being studied, long-term animal feeding trials and human experience have demonstrated that the partially hydrogenated oils in margarines and shortenings are wholesome foodstuffs. Abusive overheating of fat in air sharply decreases its palatability and nutritive value and may create minor amounts of carcinogenic materials. However, long-term animal feeding studies with properly used frying fats have revealed little, if any, effect on life span and incidence of pathological conditions.     

Spurennachweis von mehrfach verzweigten Fettsäuren in Fetten

Detection of Traces of Polybranched Fatty Acids in Fats A method for the detection and quantitative determination of saturated polybranched fatty acids in animal and vegetable fats is described. The method is based on gas-chromatographic determination of polybranched fatty acid methyl esters in the methyl esters which do not form urea adducts. The following amounts of polybranched fatty acids were determined in animal fats: whale oil 15 000 ppm., fish oil 6000 ppm., butter fat 4000 ppm., beef tallow 2000 ppm. and lard 110 ppm. In different vegetable oils and fats upto 200 ppm. of polybranched fatty acids were found. Not only the difference in total content of polybranched fatty acids but also differences in their percentage composition and retention volumes in gas-chromatograms were found. This method therefore offers the possibility of identification of some of the animal fats.     

Fettsäure-Spektren wichtiger Nahrungsfette

Fatty Acid Composition of Important Dietary Fats The recommendations issued by the German Nutrition Association (DGE) include both total fat quantities and the distribution of fatty acids in daily food intake. It is recommended that fats should account for 30% of the daily energy intake, comprising 10% each of saturated, mono-unsaturated and polyunsaturated fatty acids. An increasing number of scientific studies are quoted according to which the chain lengths of saturated fatty acids and the stereoisomers of unsaturated fatty acids play a part in raising the blood cholesterol level. Examples are given of both vegetable oils and fats and a animal and “hidden” fats. Recommendations from DGE for fat intake and fatty acid composition in fat in Germany are not reached yet. The fat intake has to be reduced.     

Aspekte bei der Hydrierung von Fetten und Fettsäuren

Aspects of Hydrogenation of Fats and Fatty Acids Hydrogenation of fat products is of great significance, both for human and animal nutrition as well as for technical purposes. In the area of nutrition, adequate food for the increasing world population is unthinkable without utilization of all fat resources, that can be made available as food fats only after catalytic hydrogenation. In the area of technical use, a similar development is observed owing to shortage of mineral oils. Thus, fatty alcohols derived from vegetable oils and waxes can already compete in price with fully synthetic fatty alcohols derived from mineral oils. In the past 70 years of hydrogenation of fats till the present time, catalysts based on nickel have been most commonly used. In addition, small proportions of catalysts based on copper and noble metals have also been used. Homogenous catalysts have been used very recently. The present communication deals primarily with the hydrogenation of neutral fats and fatty acids using nickel catalysts. The aspects of selectivity and isomerization in the partial hydrogenation of neutral fats are discussed. In the hydrogenation of fatty acids and their derivatives, emphasis is laid on other factors, such as activity, poisoning and acid resistance of the catalyst. These factors are discussed.     

Tierische Fette in der Tierernährung

Animal Fats in Animal Nutrition Intensive feeding of several types of farm animals is unthinkable without the use of fats in feed formulations. Animal fats are, however, considered inferior to plant oils with respect to quality and energy utilization. In the practical application, only mixed fat formulations are used. Therefore, there is little chance that the absorption of fat from the gastro-intestinal tract is inhibited by the presence of relatively high proportions of saturated C₁₆ and C₁₈ fatty acids. Large proportions of fat are used in feeds for broilers and calves. Moreover, from nutritional viewpoint, the fat content of feeds for swine and laying hen could be increased, if technical devices for restricted feeding are used, which prevent excessive intake of energy. A higher content of fat in ruminant feed is also to be recommended. Since in monogastric animals the consistency of fatty tissues is influenced by unsaturated fatty acids of dietary fat, the use of animal fats having low content of unsaturated fatty acids is favorable for the quality of slaughtered products.     

Einfluß von Futterfetten auf die Qualität tierischer Veredlungsprodukte

Effects of Feed Fats on Quality of Animal Product At the same level of energy supply intake of fats/oils do not lead to a higher fat deposition in the carcass. Additionally, fats are carrier of fat soluble vitamins A, D, E, K and improve their absorption from the intestinal tract. The fatty acid profile of fat deposited in the organism, as for example in egg yolk is influenced by the intake of fatty acids provided by feed. This especially concerns linoleic- and linolenic acid as well as lauric- and myristic acid, High contents of polyunsaturated fatty acids negatively influence oxidative stability as well as consistency of body fat and therefore quality of animal products. An improved oxidation protection can be carried out by supplementation of antioxidants. Medium-chain, saturated fatty acids reveal positive effects on both criteria.     

Untersuchungen über die Fettverwertung der Regenbogenforelle (Salmo gairdnerii,R.) VI: Vergleichender Einsatz von 18 unterschiedlichen Futterfetten in einer gereinigten Diät

Investigations about Fat Utilization of the Rainbow Trout (Salmo gairdnerii, R.) VI: Comparative Use of 18 Different Feeding Fats in a Purified Diet In the submitted work the usability of different feeding fats as source of energy in rations for rainbow trouts is reported. In comparison to 10% of sunflower oil in a standard diet the same amount of examined fats (maize germ oil, rice oil, lard, Novitol-30) with a share of less than 3% of essential linolenic acid (18:3, n-3) produced a just so good utilization. Only olive oil with an unbalanced high content of oleic acid decreased significantly. If a share of 6–7% in 18:3, n-3, fatty acids was contained in the feeding fat (rape seed oil poor in erucic acid and rich in erucic acid, raw and refined soya bean oil, refined soya fatty acids) the utilization increased significantly. The best result was achieved by addition of refined soya fatty acids with 15% 18:3, n-3, or red perch oil with a share of 17% 20:5, n-3 and 22:6, n-3. If beef tallow and especially micronized hardened fatty acids were used whose melting point was far beyond 40°C, a significant decrease in utilization was noticed. These fats proved to be less suitable as source of energy in rations for rainbow trouts. The same good characteristics of utilizations as with soya bean oil and rape seed oil were found in case of use of mixed animal fats, though no essential fatty acids were contained. An explanation could not be found. Linseed oil came off badly, though a surplus of essential fatty acids 18:3, n-3 was contained. The high rate of oxidations of the three fold unsaturated linolenic acid and as result a lacking absorption might be the cause.     

Fat in today’s food supply—Level of use and sources

Nutrient fat—food fats and oils, as well as fat from meat, milk, and other fat containing foods—in the U.S. food supply has increased ca. one-fourth over the past 60 years or so on a per person/day basis. Ca. two-fifths of the fat currently comes from fats and oils, including butter; over a third comes from meat (including fat pork cuts), poultry, and fish; and ca. one-eight comes from dairy products. This large increase in nutrient fat is due mainly to the use of more vegetable fats—margarine, shortening, and salad and cooking oils. The per capita amount provided by animal fats actually has decreased, because the large decreases in consumption of butter and lard are only partly offset by increases in fat associated with greater consumption of meats. Despite the decrease in consumption of animal fats, they continue to provide ca. one-fourth of the total calories. Although the proportion of calories from vegetable fats has increased, animal products still account for the largest share of the calories provided by fat. Shifts in sources of fat and the increased amount of fat have changed the fatty acid content of the food supply. One of five papers presented at the symposium, “Status of Fat in Food and Nutrition,” AOCS Fall Meeting, Chicago, September 1973. ARS, USDA.     

Prüfung verschiedener Rückstände aus der industriellen Fettsäurengewinnung an Broilern

Examination of Various Residues from the Industrial Fatty Acid Production on Broilers During industrial fatty acid production residues from various starting materials (as fish, rape seed, soya oils, tallow and stearin) occur. As according to the decree for feed there is no permission for these by-products, tests with broilers should show whether they are suitable for feeding. Altogether six tests with various types of residues were carried out; their composition (among others fatty acid pattern, amounts of polymer and oxidized fatty acids, contents of various elements) was determined. Feed take up, increase in weight and feed exploitation were the basic criteria for feeding tests. Beyond that various organs of the slaughtered bodies were investigated by chemical methods for minerals, trace elements, vitamins, fats and fatty acid pattern as well as by microscope. Because of the very extensive best results it can be stated that the pure residues, added with 10% to the same basic feed partly led to lower increase and worse feed exploitation. Its reason is probably the missing exploitation of the amounts of polymer and oxidized fatty acids. It was not possible to detect a toxicological effect of the residues.     

Fettsäurenaufnahme des Menschen und Möglichkeiten der Beeinflussung durch die Tierernährung

Fatty acid intake of men and possibilities to influence the intake by animal nutrition. About 70% of total fat intake (≈ 100 g per person per day) are from fat of animal origin in Germany. Animal nutrition may influence fat content and fatty acid pattern in animal products. This paper summarizes the influence of feeding on fatty acid pattern of meat (pork, beef, poultry, rabbit, fish), milk and eggs. Fatty acid intake is demonstrated under consideration of fat intake of men and variation of fatty acid pattern of various fats of animal origin. Daily fat intake of men amounted to 43 g saturated, 37 g monoen and 13 g polyen fatty acids. It may vary between 38 and 46 g saturated, 33 and 45 g monoen and 11 and 17 g polyen fatty acids if variation of fatty acid pattern of animal fats is considered. By combination of lower fat intake and changed fatty acid pattern of animal products fatty acid intake may be changed to more monoen and polyen fatty acids.     

What correlation is appropriate to evaluate biodiesels and vegetable oils higher heating value (HHV)?

The heating value is one of the most important properties of animal fats, vegetable oils and biodiesels for their use as fuels in stead of petroleum.There are lots of formulae or correlations encountered in the literature to evaluate biomass fuels’ higher heating value (HHV). Lots of them are not specially established for vegetable oils, animal fats and their derivatives. In this paper, some correlations previously published and based on ultimate analysis or fatty acid composition are applied to some bio oils samples collected from the literature. The aim of this article is to investigate what of them can be used to estimate animal fats, biodiesels, vegetable oils and their derivatives HHV with a high accuracy. With an absolute average error inferior to 4%, the results show that the formulae of : Channiwala and Parikh, Boie and Vondracek, Boie, Vondracek, Fassinou et al. Milne, IGT, Demirbas and Dulong can be used at this purpose with a high accuracy by comparison to the bomb calorimetric method.     

Die Zusammensetzung tierischer Organ- und Depotfette in Abhängigkeit von der Fütterung III: Gas-chromatographische Analyse von Kälberfetten nach definierter Fütterung

The Composition of Animal Organ and Depot Fats in Relation to Feed III: Gas-chromatographic Analysis of Fats from Calves after Definite Feed Within the scope of the feeding experiments, which had been carried out for explaining the accumulation of trans fatty acids in animal organs, we studied the composition of mixed fatty acids of heart, kidney and liver as well as that of the corresponding depot fats with the help of gas-chromatography. The fatty acid composition of the separated neutral fat and phosphatide fractions of the organ fats are discussed.     

Effect of PUFA at sn‐2 position in dietary triacylglycerols on the fatty acid composition of adipose tissues in non‐ruminant farm animals

The influence of the distribution of polyunsaturated fatty acids on the glycerol backbone of dietary triacylglycerols on the fatty acid profile of adipose tissue and muscle phospholipids was investigated in growing‐finishing pigs (48) and broiler chicken (84). The animals were fattened on barley/soybean meal diets supplemented with a blend of soybean oil and beef tallow, either in the ratio 3:1 w/w (high‐PUFA) or 1:3 w/w (low‐ PUFA). Part of the high‐ and low‐PUFA blends was chemically interesterified to randomly distribute all fatty acids over the three positions of the glycerol. Thus, two sets of diets of identical overall fatty acid composition, but differing in the distribution of fatty acids in the triacylglycerols, were fed. Growth performance and carcass composition were neither affected by fatty acid composition nor by randomisation of dietary fats in either animal species. Apparent digestibility of energy was slightly lower in pigs fed the low‐PUFA blends. Fatty acid profile of subcutaneous fat of pigs and broilers as well as of internal body fat (lamina subserosa) and muscle phospholipids of pigs varied according to the dietary fatty acid composition but was not affected by randomisation of dietary fats. These findings are explained in terms of the hydrolysis of TAG during transport of lipids from enterocytes to adipose tissue cells and the continuous lipolysis and re‐esterification of fatty acids that take place in adipose tissue cells.     

Fats and oils as feedstocks for oleochemicals

The approximate quantity of 3 million tons estimated to be required at present for the production of oleochemicals is to be covered from a total production of more than 60 million tons of vegetable and animal fats. While the quantity of eleochemicals produced has nearly doubled in recent years, vegetable oil production alone has increased from 25 to 40 million tons in the same period. More than half the feedstocks required for oleochemicals are acid oils and other fats and oils which are unsuitable for human food. The demand for fats and oils for oleochemicals will certainly grow for price and technological reasons, but only the use of large quantities of oils and fats for diesel engines could shift this balance drastically and endanger the world supply of edible fats. A bottleneck may arise in the supply of fatty acids of medium chain length, although the use of coconut and palm kernel oil by the food industry in the highly developed countries has been on the decline. The green revolution goes on and the fat supply grows faster than the population. In addition, new approaches to plant breeding and agriculture, and biochemical processes as well, might help circumvent any conceivable shortage in the supply of oils and fats in general, and in the supply of special fatty acids in particular.     

Biodiesel processing and production

Biodiesel is an alternative diesel fuel that is produced from vegetable oils and animal fats. It consists of the monoalkyl esters formed by a catalyzed reaction of the triglycerides in the oil or fat with a simple monohydric alcohol. The reaction conditions generally involve a trade-off between reaction time and temperature as reaction completeness is the most critical fuel quality parameter. Much of the process complexity originates from contaminants in the feedstock, such as water and free fatty acids, or impurities in the final product, such as methanol, free glycerol, and soap. Processes have been developed to produce biodiesel from high free fatty acid feedstocks, such as recycled restaurant grease, animal fats, and soapstock.     

Investigations on physical refining of animal fats and vegetable oils

Alcohols, polyethyleneglycols, supercritical fluids, and some of their mixtures have been investigated as to their usefulness to purify animal fats and vegetable oils by extraction. The main impurities are free fatty acids. Phase equilibrium was measured as function of temperature and pressure. As primary substances abattoir fat and palm oil were used. Carbon dioxide, dimethylether, and mixtures thereof, likewise methanol and ethanol were tested as extractants for free fatty acids by counter-current extraction in a pilot plant including a high-pressure column and by cross-flow extraction on laboratory scale. With experiments and process simulations including the recovery of the extractants the deacidification of animal fats and vegetable oils was found to be possible. Polyethyleneglycols extract carotenes together with free fatty acids. With the physical refining methods investigated, the formation of waste materials was avoided.     

Über den Zusammenhang von Fleisch- und Fettbildung bei wachsenden Tieren

Relationship Between the Formation of Meat and Fat in Growing Animals Production of slaughter animals as human food means, primarily, the production of protein and fat. The production of protein is by far the most important objective. In contrast, the animal fat is generally considered as an undesirable component of foods. Although the arguments against the use of animal fats compared to vegetable fats are only to some extent justified, efforts have been made since many years to reduce the fat content and increase the proportion of meat by various means, such as breeding, special feeding and other techniques for raising animals. However, considerable amounts of fat are still produced besides meat in the production of slaughter animals. In swine and cattle the extent of formation of meat and fat during various stages of growth, the distribution of fat in various parts of the animals, the differences in fatty acid composition and means to alter them are discussed.     

The effect of dietary fat on the glyceride structure of rat carcass fat

Carcass fats were obtained from weanling rats fed a complete diet for 8 weeks, which consisted of 2% cottonseed oil and 10% of the following fats: (1) corn oil; (2) the fatty acids of corn oil; (3) triricinolein; (4) ricinoleic acid; (5) the hydrogenated fatty acids of castor oil ; and (6) commercial hydrogenated shortening. The fats were subjected to both pancreatic lipase and nonspecific hydrolysis ; the resulting acids converted into methyl esters by conventional methods, and subjected to gas Chromatographie analysis. From these data, the positional distri-bution of the component fatty acids, glyceride types, and isomeric forms were calculated. The results indicated a preferential placement of un-saturated acids in the 2- position of the carcass triglycerides and that the carcass fat composition in terms of unsaturated (U) and saturated (S) fatty acid composition is not greatly influenced by the S and U compositions of the dietary fat. It was found that hydroxy acids or their tri-esters are metabolized much the same as are normal triglycerides and exert no particular in-fluence upon the fat structure of the rat. Some type of relationship between the dietary U and the U₃ in the carcass fat appears to be present. The glycerides of the carcass fats examined here are essentially a random mixture of the major glyceride types, but the isomeric forms (SUS, S SU, USU and UUS) are a definite non-random mixture. Carried out at the Food Res. Div., Armour & Co., and at The Burnsides Research Laboratory under research grant No. EF 225 from the National Institutes of Health, U. S. Public Health Service, and Deparmtent of Health, Education, and Welfare.     

Detection of Adulterated Milk Fat by Fatty Acid an Triglyceride Analysis

On the basis of variation ranges of fatty acids (83 milk fats) and triglycerides (763 milk fats) the limits of detection of foreign fats (13 different types) in milk fat are determined. In this respect, on the basis of certain ratios of triglycerides only for soybean oil, sunflower oil, and olive oil and also fo ratios of fatty acides only for soybean oil, sunflower oil, coconut oil and palm kernel oil low limits of detection of <5% were established. On the other hand triglyceride formulae with up to 8 individual triglycerides permit a sensitive qualitative (2–5%) and quantitative detection of all vegetable and also animal non-milk fats in milk fat, even with special feeding conditions of the cows (e.g. fats, Ca-soaps).     

Die Weiterentwicklung der Codex Alimentarius Standards für Öle und Fette

Further Development of Codex Alimentarius Standards for Oils and Fats A report is given on the further development of Codex Alimentarius Standards for oils and fats, which was discussed in the 9th meeting of the Codex Committee on Fats and Oils from 28th November to 2nd December 1977 in London. Topics discussed were a collaborative report by FAO and WHO on the role of fats in human nutrition, the general standard for oils and fats, and standards for reduced fat margarine, low erucic acid rapeseed oil, coconut oil, palm oil, palm kernel oil, babassu oil, grape seed oil as well as marine oils. Furthermore, the limits of fatty acid composition as criteria for identification of specific oils and fats were discussed.