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.     

Production methods for the manufacture of crude tall oil and its subsequent processing

Summary The source of crude tall oil and methods to produce the oil have been described. These include acidulation of sulfate pulp, black liquor skimmings, and gravity settling as well as centrifugal means of separation to reduce the lignin content of the product. Subsequent processing of the crude tall oil into fractionated fatty acids and rosin has been outlined with suggestions for consideration in all stages of the distillation section of the plant.     

On the formation of degradation products from the pyrolysis of tall oil fatty acids with kraft lignin

Mixtures of tall oil fatty acids and kraft lignin from southern pine wood were pyrolyzed at 160 C and 280 C with or without exclusion of oxygen. In addition to fatty acids of various chain lengths and aromatic degradation products from lignin, a number of homologousn-alkylbenzenes were formed (ca. 1.5%) and characterized by gas chromatography-mass spectrometry. The possible ways of formation of the latter from fatty acids are discussed briefly.     

Tall oil fatty acid marketing

Once considered a low cost by-product of crude tall oil fractionation, tall oil fatty acids are now being used for their own distinctive and specific properties in special applications. Consumption of tall oil fatty acids in protective coatings, soaps, and ore flotation has declined in recent years, however, usage in chemical intermediates has increased significantly in the past 10 years. These intermediates are dimer acids, oleic and linoleic acids, epoxidized esters, amidoamines, and diacids. Static tall oil production during the mid 1970s caused by changes in paper mill operations (i.e., continuous digestion, waste recycling, increased usage of chips and hard wood) has increased the demand for higher priced oleic acid and other unsaturated fatty acids.     

Solvent extraction of fatty acids from natural oils with liquid water at elevated temperatures and pressures

The use of liquid water at elevated temperatures and pressures as an extractive solvent for separating mixtures of compounds which occur in natural oils has been studied. A southern pine tall oil and a distillate from the deodorization of soybean oil were extracted with liquid water at temperatures from 298 to 312°C and pressures between 103 and 121 bar. Results indicate that water can be used to extract fatty and resin acids from crude tall oil to obtain a product with a high acid content that produces less pitch during distillation. The process can also be used to extract fatty acids from vegetable oil deodorizer distillate.     

Distillability of extracted mixed-birch tall oil

Chemical and physical properties of tall oil made in the CSR process and distillation results of three different types of distillation plants are presented. Chemically extracted, mixed-birch, tall oil differs remarkably from the normal Scandinavian crude tall oil. The extracted oil deviates from the normal, unextracted, mixed-birch tall oil with respect to the smaller unsaponifiable amount and the fatty acid esters. The amount of resin acid is small in extracted mixed-birch tall oil. The quantity of fatty acids, especially that of saturated fatty acids, is large. Distillation of extracted mixed-birch tall oil is most successful in a distillation plant where thin film evaporators are used.     

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.     

The preparation of C19 dicarboxylic acid by the koch reaction

This paper describes the preparation of C₁₉ dicarboxylic acid by the Koch reaction with carbon monoxide and sulfuric acid of oleic, tall oil fatty, and partially hydrogenated tall oil fatty acids. The effects of changing reaction conditions upon the yield and purity of the product were examined. With the best conditions, it was possible to prepare light-colored, heat-stable C₁₉ dicarboxylic acid in 83% overall weight yield at 96% purity, containing 75% tertiary isomers and 25% secondary.     

Evaluation of peanut and cottonseed oils for deep frying

A comparative study of cottonseed and peanut oils for frying of potato chips was undertaken. Industrial scale frying was conducted for 5 days with cottonseed and 5 days with peanut oil and frying oils and chips were sampled twice a day. Frying oils and oils extracted from stored chips were analyzed for ultraviolet absorption (A₂₃₂ and A₂₆₈), peroxide and acid values. Tocopherol and tertiary butylhydroquinone levels were determined by high performance liquid chromatography. Chips stored at room temperature for 12 weeks were organoleptically evaluated. During the first 20 hr frying the A₂₃₂, free acid and peroxide values of cottonseed oil increased rapidly, exceeding that of peanut oil, which increased moderately. For both oils, constant values were attained during the next 80 hr period, followed by moderate increases during the last 23 hr. Peanut frying oil lost 55% of its tocopherols and 54% of its tertiary butylhydroquinone during frying (103 hr), whereas cottonseed frying oil retained these compounds at the original levels. Tocopherols were also better retained in chips fried in cottonseed oil than in peanut oil. The fatty acid patterns of frying oils and oils extracted from chips did not show significant changes due to frying and storage, respectively. These results, therefore, suggest that cottonseed oil is sufficiently stable to be used as a substitute for peanut oil in deep frying.     

Effect of Storage Conditions on the Oil Quality of Chinese Tallow Tree Seeds

The Chinese tallow tree (TT) has been widely considered to be an invasive species in the US without potential benefits. However, the literature on TT seeds is scarce and the effect of storage conditions on seed oil quality in particular has not been published to our knowledge. Prior research revealed that TT has a very high yield of seeds containing large percentages of long and short chain fatty acids (mainly palmitic fatty acid, along with some oleic, linoleic and linolenic fatty acids), which can be base transesterified into biodiesel. This study aims to address the issue of the quality of the kernel oil of TT seeds stored at different temperatures (4 °C and room temperature) and under controlled atmosphere storage conditions (3% CO₂, 6% CO₂, vacuum, normal headspace). The total storage time was 3 months with the oil quality being analyzed weekly. Extracted oil was analyzed by titratable acidity, peroxide value, oxidative stability index and fatty acid composition. These experiments provided evidence that, after 12 weeks of storage, a controlled atmosphere did not produce any remarkable advantage over low cost air storage. The results validate the belief that no elaborate storage conditions are required to store this economically promising high oil content biofuel feedstock.     

The rate of development of acidity in stored tung seeds and kernels

Summary Whole tung seeds, whole kernels, and chopped kernels of high, medium, and low moisture contents were sealed in tin cans and stored in incubators maintained at 25°, 31°, and 38°C. At intervals samples were removed and the acid value of the oil determined. The different temperatures used had slight effect on the rate of development of free fatty acids in the oil of the whole seeds and kernels, but the higher temperatures greatly increased the rate of development of free acid in the chopped kernels. Whole seeds containing 7% and 12% moisture were stored for 4 weeks and seeds containing 17% moisture were stored for 2 weeks, during which periods the oils developed free fatty acids equivalent to acid values of 2.0 or less. Under none of the conditions used did the acid values of the oils exceed 8.0 after storage for 13 weeks. Whole kernels developed even less free fatty acids than seeds stored under similar conditions. Kernels containing 4% and 6% moisture were stored for 12 weeks during which period the acid value of the oil never exceeded 1.5. Even in kernels containing 12% moisture the acid value of the oil did not exceed 6.0 at the end of 12 weeks. Chopped kernels with moisture contents of 5% and 7% could be stored for 12 days without developing an acid value in the oil of more than 8.0. However chopped-kernels with a moisture content of 12% developed an acid value in the oil in excess of 8.0 in less than a week. Whole seeds with as much as 15% moisture could probably be stored for several weeks without developing an objectionable amount of free fatty acids. Since commercial hulled “nuts” practically always contain some broken kernels, to avoid development of free fatty acids in storage they should be dried to 10% or less moisture before storage. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Origin of bicyclic fatty acids in tall oil

It was shown that two bicyclic fatty acids present in Finnish tall oil were formed from (5Z, 9Z, 12Z)-5, 9, 12-octadecatrienoic acid, pinolenic acid (I). Under the alkaline conditions of sulfate pulping, pinolenic acid forms conjugated isomers which undergo Diels-Alder cyclization during the heating in the tall oil distillation. The cyclization products, here called cyclopinolenic acids, are bicyclic fatty acids and stereoisomers of 4-(5-pentyl-3a, 4,5,7a-tetrahydro-4-indanyl) butanoic acid (IV and V).     

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.     

Sunflowers: America’s neglected crop

The sunflower,Helianthus annuus, is a crop which has been neglected in American agriculture. Sunflower oil from seed grown in the northern U.S. typically contains 70% linoleic acid and has a high ratio of polyunsaturated to saturated fatty acids. This makes it desirable as an edible oil in light of evidence linking saturated fats to high blood cholesterol and incidence of heart disease. In contrast sunflower oil from seed produced in the South generally contains 40–50% linoleic acid. Preliminary studies indicate that southern oil with a lower content of linoleic acid is slightly more stable than northern oil. The effect of planting dates, location and environmental temperatures on the fatty acid composition of northern and southern sunflower oils is reported. Studies also show that potato chips fried in sunflower oil are more flavorful after storage for four weeks than similarly treated chips fried in cottonseed-corn oil mixtures. Sunflower protein is highly digestible (90%) and possesses a high biological value (60%). Protein isolates prepared by the conventional method of extraction are greenish in color due to oxidation of chlorogenic acid. However research underway indicates that development of a nearly white isolate is possible. Analysis of chemical, physical and organoleptic properties indicate that dehulled sunflower kernels can be used in various food products. Defatted meal also can be used as a partial wheat substitute in bread and other bakery products. Presented at the AOCS Meeting, Atlantic City, October 1971.     

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.     

Processing of byproducts from carbonisation of non-caking coals: recovery of tar acids

Recovery of tar acids from ammoniacal liquor and middle oil fraction (170–270°C) of tar produced in the Woodall–Duckham type carboniser of Dankuni Coal Complex (DCC), using non-caking coals, has been investigated. About 99.5% of the phenols contained in ammoniacal liquor can be extracted with isobutyl acetate in five stages of extraction using a feed:solvent ratio of 8:1 (v/v) and the phenols content of the liquor can be reduced from about 6000 to 30 ppm. A comparison of products obtained from tar distillation under laboratory conditions to those under actual plant operation has been made. The optimum yields of the middle oil, under standard laboratory distillation and tar distillation plant, were 27.12% and 22.5%, respectively, on dry tar and the content of the refined tar acids in these oil fractions were found to be 9.35% and 7.6% (on dry tar), respectively. However, in actual plant practice, this level of yield has not been achieved yet, due to loss of substantial quantity of tar acids in processing units. With a view to optimising the yield, various aspects of plant operation and process streams were investigated. The yields of tar acids and the other processing streams of DCC have been compared with those of metallurgical coke plants and variations in composition of tar acids discussed. The dihydric phenols (ca. 16% of tar acids) obtainable from DCC, have been shown to offer an attractive potential. The environmental aspects related to discharge of waste streams have been dealt with.     

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.     

Thermochemical Conversion of Black Liquor in the Liquid Phase

Abstract

Black liquor from kraft pulping of pine wood was pressure heated (about 20 MPa) for 45 minutes at both 300 °c and 350 °c and in both the presence and absence of a reducing atmosphere. Variable amounts of organic-phase (40–64 % of the black liquor organics), water-soluble (14–70 %), and volatile (12–55 %) products were formed. The organic-phase product originates mainly from the lignin fraction of black liquor, whereas, during the treatments, the corresponding hydroxy acid fraction was primarily degraded into lower acid intermediates and volatile components. The effects of temperature and gas atmosphere (carbon monoxide, hydrogen or nitrogen) on the conversion of black liquor are discussed.     

Effects of Lupin Oil on Carp Lipids during Chilling 2. Changes in Fatty Acid Composition

Rearing carp for 6 weeks on diets containing 5% lupin oil slightly affected the composition of the component fatty acids in various lipid classes of the fillets. On the other hand, the incorporation of lupin oil in the diet did not affect the trend in the changes occurring in the component fatty acids of the different lipid classes during chilling storage of the carp fillets. Thus, the percentage of saturated and monounsaturated fatty acids increased whereas the percentages of polyunsaturated fatty acids decreased during storage.     

Isolation and identification oftrans-3,5-dimethoxystilbene from high quality tall oil fatty acids by liquid chromatography and mass spectrometry

trans-3,5-Dimethoxystilbene has been isolated from high quality tall oil fatty acids (unsaponifiables 1.5% maximum, rosin acids 1.5% maximum), using liquid column chromatography and low temperature solvent fractional crystallization. The structure of this compound was determined with the aid of IR, mass and NMR spectrometry. Thetrans-3,5-dimethyoxystilbene was found to be responsible for the development of a red color during the epoxidation of the tall oil fatty acids.