Tall oil fatty acids

About 1949, with the advent of effective fractional distillation, the tall oil industry came of age, and tall oil fatty acids (TOFA), generally any product containing 90% or more fatty acids and 10% or less of rosin, have grown in annual volume ever since, until they amount to 398.8 million pounds annual production in the U.S. in 1978. Crude tall oil is a byproduct of the Kraft process for producing wood pulp from pine wood. Crude tall oil is about 50% fatty acids and 40% rosin acids, the remainder unsaps and residues; actually, a national average recovery of about 1–2% of tall oil is obtained from wood. On a pulp basis, each ton of pulp affords 140–220 pounds black liquor soaps, which yields 70–110 pounds crude tall oil, yielding 30–50 pounds of TOFA. Separative and upgrading technology involves: (a) recovery of the tall oil; (b) acid refining; (c) fractionation of tall oil; and occasionally (d) conversion to derivatives. TOFA of good quality and color of Gardner 2 corresponds to above 97% fatty acids with the composition of 1.6% palmitic & stearic acid, 49.3% oleic acid, 45.1% linoleic acid, 1.1% miscellaneous acids, 1.2% rosin acids, and 1.7% unsaponifiables.     

The behavior of resin acids during tall oil distillation

The behavior of resin acids during tall oil distillation was studied by analyzing samples from six industrial-scale processes. The same artifact resin acids were formed in all processes. However, the proportion of artifact resin acids in tall oil rosins varied from 8.3 to 18.3% of the resin acids. The lowest values were found for two processes utilizing thin-film evaporators. The yield of resin acids in the tall oil rosin fraction varied from 62 to 80% of the resin acids in the crude tall oil feeds. Dehydroabietic acid was formed in all processes, the amount in rosin being 14-44% more than in the crude tall oil feed. Of the abietic acid, only 45-82% was recovered in the tall oil rosin fraction. The distribution of various resin acids and their reaction products during distillation was determined. Major resin acid impurities in tall oil fatty acids were 8,15-pimaradien-18-oic acid and 8,15-isoprimaradien-18-oic acid, both formed chiefly during distillation, and two secodehydroabietic acid isomers common in crude tall oils. The reactions of resin acids leading to new isomers or non-acidic products are discussed. Some results of this work were presented at the 173rd American Chemical Society Meeting, New Orleans, March 1977.     

Destillationsprobleme der Tallölaufbereitung

Problems of Distillation in the Processing of Tall Oil Large scale distillation of tall oil for the separation of the major components, fatty acids and rosin acids, involves difficulties owing to the presence of numerous other components, which, under the conditions of distillation, react with the active groups of the acids and the double bonds. The present communication shows the conditions which minimize such undesirable side reactions and additional thermal and oxidative decompositions, that reduce the yield of fatty acids and rosin acids. According to process, developed by the author, a countercurrent degasing and dewatering treatment with stripping steam is carried out before the separation of pitch, in order to remove rapidly at low temperatures the volatile substances, which negatively affect the odour, colour and colour stability. A vacuum of 100 torr enables the condensation of fairly large amounts of the stripping steam used by means of cooling water. Thus, the vacuum system is not affected. The distillative separation of pitch is carried out in two stages. The temperature of tall oil reaches a maximum of 230°C for the recovery of 90% of the distillate. In the second stage of film evaporation, the temperature of the product reaches 255°C for a short period. In the final distillation of the mixture of fatty acids and rosin acids, free of pitch, ACV-trickle columns and specially constructed falling film evaporators are used, which ensure that the temperature of the still does not exceed 260°C and the excess temperature of the heating medium is not more than 20°C. In case the temperature of the product exceeds 250°C in the falling film evaporator, addition of a few percent of stripping steam at their heads prevents the undesirable formation of anhydride.     

Spectrophotometric analysis of tall oil rosin acids

Summary About half of the rosin acids in whole and distilled tall oil consist of abietic and neoabietic acids, as distinguished from hydroabietic acids, dehydroabietic acid, and the pimaric acids. In this respect the tall oil rosin acids are similar to those from gum or wood rosin. This was established by spectrophotometric analysis of the rosin acids from whole tall oil, double distilled tall oil, rosin acids crystallized from tall oil, and rosin acids separated from tall oil by fractional distillation. The rosin acids crystallized from tall oil contained the highest percentage of abietic acid, but the sum of abietic and neoabietic acids was only slightly higher. The rosin acids from acid refined tall oil contained appreciably less abietic and neoabietic acid than the others. Before spectrophotometric analysis the rosin acids were isolated from the tall oils in about 95% yield by cyclohexylamine precipitation.     

Changes in the Composition of Tocopherols and Fatty Acids in Postdeodorisation Condensates during Refining of Various Oils

For refining of different plant oils the same industrial installations are used and the last stage is the process of deodorisation. The waste product obtained during the deodorisation process is the postdeodorisation condensate (oil scum). Oil scum contains several valuable components, such as polyunsaturated free fatty acids and tocopherols. Qualitative and quantitative composition of tocochromanols and free fatty acids depend on the kind of the refined oil. Postdeodorisation condensates from the refining of rape, sunflower and soybean oils were investigated. Prevailing acid in all postdeodorisation condensates was the oleic acid the quantity of which ranged from 50% to 58.7%. Second was the linoleic acid, which was found in quantity amounting to 20% during the refining of rape and soybean oils, but in the condensate coming from sunflower oil its content was by 10% greater. The results obtained during quantitative determination of tocochromanols correlated with their quantity in oils, but we observed greater distillation of γ-T and α-T than of δ-T. The reason for this is smaller quantity of δ-T in the oil which is undergoing the process of deodorisation.     

Characterization of palm acid oil

Palm acid oil (PAO) is a by-product obtained from the alka-line refining of palm oil. It is used for making laundry soaps and for producing calcium soaps for animal feed formulations. The properties and composition of PAO may differ according to variations in the palm oil feedstock and the alkaline refining process. Because information on the characteristics of PAO is limited, this investigation aims to establish the properties of this product. Quality and oxidative parameters of 27 samples of PAO were determined. The six parameters analyzed were moisture and free fatty acid content, peroxide value, iodine value, saponification value and unsaponifiable matter. Headspace-gas-chromatographic (HSGC) analysis and gas-chromatographic analysis of the extract from Likens-Nickerson steam distillation of the samples were also carried out. Mean moisture content was 0.98%, free fatty acids 62.6% (palmitic acid), peroxide value 4.1 meq/kg, iodine value 50.2, saponification value 186 and unsaponifiable matter 0.53 HSGC profiles of a few samples showed the presence of one to three peaks, while the steam distillation extract showed the presence of aldehydes, ketones, furans and acids.     

Production and utilization of palm fatty acid distillate (PFAD)

PFAD (palm fatty acid distillate) is a by‐product of physical refining of crude palm oil products and is composed of free fatty acids (81.7%), glycerides (14.4%), squalene (0.8%), vitamin E (0.5%), sterols (0.4%) and other substances (2.2%). PFAD is used in the animal feed and laundry soap industries as well as a raw material for the oleochemicals industry. Vitamin E, squalene and phytosterols are value‐added products which could be extracted from PFAD and are of potential value for the nutraceutical and cosmetic industries.     

Fractional distillation

While practically all the fatty acids produced in the fatty acid industry are distilled products, these materials are all, at least to some degree, fractionated fatty acids. Rarely indeed are today’s fatty acids suited for any of the many applications to which they are put without the quality and homolog distribution improvements which only fractional distillation can guarantee. Thus, this separation is of vital importance within the fatty acid and derivative industries. Fractional distillation is industrially a practical separative method for: (a) 16:0 and 18:0 fatty acids, such as those derived from hydrogenated fats and oils like tallow, soybean, cottonseed soapstocks, palm oil and others; (b) 18:0, 20:0, 22:0, and 24:0 fatty acids from hydrogenated fish oils or high erucic rapeseed oil; and (c) 8:0, 10:0, 12:0, and 14:0 fatty acids from the hydrogenated fatty acids from the lauric oils group (coconut, palm kernel, babassu, etc.). While theoretically possible under idealized conditions in the laboratory, it is not practical to separate palmitic, oleic, heptadecanoic, and stearic acids by means of fractional distillation     

Studies in soap crystallization processes. Part III. Acid soap crystallization in the segregation of tall oil fatty acids

Tall oil fatty acids have been fractionated into 80–90% oleic acid, and 60–80% linoleic acid fractions, by precipitation of the oleic acid as acid soap from polar solvents. Sodium and potassium acid soaps are equally effective, but ammonium acid soaps require lower operating temperatures. The choice of solvent is not critical as regards degree of separation, but technically attractive filtration rates have been obtained only with methanol and acetone. Acidulation gives colorless oleic acid of very low rosin acid and unsaponifiable content, but with 5–10% of conjugated linoleic acid.     

Capillary gas chromatography-mass spectrometry of resin acids in tall oil rosin

The resin acid composition of Finnish tall oil rosin was investigated by gas chromatography and mass spectrometry employing open tubular capillary columns. On a column coated with 1,4-butanediol succinate, 16 resin acids found in tall oil rosin samples were well resolved, and mass spectra could be recorded. All resin acids were confirmed to be of the pimaric and abietic types by gas chromatographymass spectrometry. Eight of the acids were not detected in the corresponding crude tall oils and evidently had been formed during the technical distillation process. The presence of 8,15-pimaradien-18-oic and 8,15-isopimaradien-18-oic acids in the rosin, but not in the crude tall oil, indicates that the pimaric type acids also undergo extensive isomerization during tall oil distillation. Additionally, three dihydroabietic acids and two acids with identical mass spectra, tentatively stereoisomers of 7,9(11)-abietadien-18-oic acid, were formed during the distillation process.     

Möglichkeiten des Umweltschutzes bei der physikalischen Raffination und Fettsäuredestillation

Feasibilities of Environmental Protection Concerning Physical Refining and Fatty Acid Distillation In the present work the accomplishment of the statutory decrees of today concerning waste water and waste air in the field of physical refining, of edible oil deodorization, of straight distillation and the fatty acid fractionation with respect to the necessary need of working stock and devices is investigated. The resulting environmental loads depend beside the tightness of the plant which can be influenced by the apparatus, on the composition and the physical properties of the components of the occurring vapour which is finally exhausted by the vacuum aggregate. In this context the content of inertgas and water on the one hand and their condensation behaviour on the other hand are of special importance. Their correlations are explained by examples of physical refining and deodorization of oils as well as straight distillation and fractionation of fatty acids. As saturated pure products of the higher fatty acids have the highest solidification points, they tolerate the slightest inert gas load in form of carrier steam and should be distilled - if possible - without open steam. The properties of crystallization as well as solubilities in water of the occurring distillates of physical refining, oil deodorization and straight distillation of fatty acids determine the lowest waste gas temperature after condensation which is still allowed, and by that the quantity of light parts which come into the vacuum system by the inert gases inclusive the used carrier steam to condensate there together with the water vapour.     

Preparation of Medium Chain Triglycerides with the Use of Physical Refining

The application of medium chain triglycerides (MCTs) of fatty acids, mainly with C₈ and C₁₀ carbon atoms, has extended in recent years from their original clinical use for patients with deficient lipid metabolism to their utilization in infant and parenteral feedings. They may be useful in treating obesity and various other ailments. The medium chain fatty acids are prepared by fractional distillation of coconut and palmkernel oil fatty acids and the industrial synthesis of MCTs is much more complicated than the preparation of common edible oils. The esterification of medium chain fatty acids with glycerol must lead to an almost complete elimination of monoglycerides because of their bitter taste. The free fatty acid content of the end product has to be very low and the deodorization step creates problems owing to the hydrolysing action of the steam. The necessity of using a large excess of fatty acids in the esterification step to eliminate the monoglycerides, results in considerable refining losses, which increase the cost of MCTs manufacture. The present investigation was carried out with the object of replacing the alkali treatment of the esterified product by physical refining, i.e. by the removal of free fatty acids by distillation. This was achived by dispensing with the use of a catalyst during the esterification and by using nitrogen or preferably carbon dioxide instead of steam during the deacidification-deodorization step. This permitted a substantial increase in the temperature of the precess and the formation of a satisfactory product in a reasonable working time.     

Production of biodiesel fuel from tall oil fatty acids via high temperature methanol reaction

Tall oil fatty acids are a byproduct of the paper industry and consist predominantly of free-fatty acids (FFAs). Although this feedstock is ideal for biodiesel production, there has been relatively little study of its conversion to biodiesel. Thus, the purpose of this study was to investigate the high temperature reaction of methanol with tall oil at subcritical and supercritical pressures to produce fatty acid methyl esters. This study investigates the effects of mixing, pressure, temperature, and methanol to oil molecular ratio in order to determine the potential use of tall oil as a biodiesel feedstock. In this work, tall oil fatty acids were successfully reacted with supercritical and subcritical methanol in a continuous tubular reactor, resulting in a reaction that is primarily temperature dependent. Conversions at subcritical pressures of 4.2 MPa and 6.6 MPa were 81% and 75%, respectively. Pressure seemed to have little correlation to conversion in both regimes, and conversions were comparable between the two. Additionally, it was found that tall oil fatty acids react well with methanol to give comparable conversions at the relatively low molecular flow ratio of 5:1 methanol to tall oil. Both of these observations suggest that hydrolyzed triglycerides or free fatty acid feedstocks would make the primary high temperature biodiesel reaction and the subsequent separation and purification operations less expensive than was previously believed.     

Improving the economics of biodiesel production through the use of low value lipids as feedstocks: vegetable oil soapstock

Semirefined and refined vegetable oils are the predominant feedstocks for the production of biodiesel. However, their relatively high costs render the resulting fuels unable to compete with petroleum-derived fuel. We have investigated the production of fatty acid methyl esters (FAME; biodiesel) from soapstock (SS), a byproduct of edible oil refining that is substantially less expensive than edible-grade refined oils. Multiple approaches were taken in search of a route to the production of fatty acid methyl esters from soybean soapstock. The most effective method involved the complete saponification of the soapstock followed by acidulation using methods similar to those presently employed in industry. This resulted in an acid oil with a free fatty acid (FFA) content greater than 90%. These fatty acids were efficiently converted to methyl esters by acid-catalyzed esterification. The fatty acid composition of the resulting ester product reflected that of soy soapstock and was largely similar to that of soybean oil. Following a simple washing protocol, this preparation met the established specifications for biodiesel of the American Society for Testing and Materials. Engine emissions and performance during operation on soy soapstock biodiesel were comparable to those on biodiesel from soy oil. An economic analysis suggested that the production cost of soapstock biodiesel would be approximately US$ 0.41/l, a 25% reduction relative to the estimated cost of biodiesel produced from soy oil.     

Improved method for rosin and fatty acids in tall oil

Journal of the American Oil Chemists' Society - An analytical procedure is presented for determination of the rosin and fatty acid contents of tall oil products. Rosin acids are determined by...     

HPLC determination of long chain saturated fatty acids in tall oil rosin

A method was developed for the analysis of long chain saturated fatty acids or their esters from tall oil or tall oil rosin. The method is specific for 18 through 28 even carbon number acids with a detection limit for each at 0.05% based on rosin. Ultraviolet detection is achieved through phenacyl derivatization. Omission of the saponification step allows selective determination of the free fatty acids.     

Physikalische Raffination von Palmöl

Physical Refining of Palm Oil In contrast to the conventional neutralization which consists of several steps, physical refining is composed of two main processing steps, namely continous desliming-prebleathing and deodorization integrated with distillation of the free fatty acids. The use of minimum amounts of chemicals under vacuum ensures no pollution of waste water. Moreover, the direct recovery of fatty acids by distillation eliminates the cumber some process of splitting the soapstock. Other advantages of this process are the reduction of refining loss and a higher purity of the recovered fatty acids. The results obtained in a new physical refining plant having a capacity of 200 t per day are given.     

Physical refining of edible oil

Physical refining of edible oils has received renewed interest since the early 1970s when the process was reintroduced on a large scale to refine palm oil in Malaysia. Subsequent laboratory and field tests have also shown that physical refining can be used as a substitute for caustic or chemical refining, not only for high free fatty acid (FFA) oils such as palm, but also on low FFA oils such as soybean oil. In either case, the physical refining system results in lower oil loss than chemical refining and also eliminates pollution problems associated with soapstock acidulation. In physical refining, however, the oil pretreatment and efficiency of the distillation are two very important factors that must be considered to guarantee continuous production of high quality products. This paper reviews the physical refining system as it is today and how it can be used on two different edible oils. An actual case study showing the effects of the pretreatment in a commercial operation is also presented. Presented at the 73rd AOCS annual meeting, Toronto, 1982.     

Lipase catalyzed synthesis of neutral glycerides rich in micronutrients from rice bran oil fatty acid distillate

Neutral glycerides with micronutrients like sterols, tocopherols and squalene may be prepared from cheap raw material like rice bran oil fatty acid distillate (RBO FAD). RBO FAD is an important byproduct of vegetable oil refining industries in the physical refining process. Glycerides like triacylglycerols (TAG), diacylglycerols (DAG) and monoacylglycerols (MAG) containing significant amounts of unsaponifiable matter like sterols, tocopherols and hydrocarbons (mainly squalene) may certainly be considered as novel functional food ingredients. Fatty acids present in RBO FAD were esterified with glycerol of varying amount (1:0.33, 1:0.5, 1:1 and 1:1.5 of FAD : glycerol ratio) for 8 h using non-specific enzyme NS 40013 (Candida antartica). After esterification the product mixture containing mono, di- and triglycerides was purified by molecular distillation to remove excess free fatty acids and also other volatile undesirable components. The purified product containing sterols, tocopherols and squalene can be utilized in various food formulations.