Vegetable oil raw materials

Vegetable oils that are important to the chemical industry include both edible and industrial oils, which contribute 24% and 13.5%, respectively, compared to 55% for tallow, to the preparation of surfactants, coatings, plasticizers, and other products based on fats and oils. Not only the oils themselves but also the fatty acids recovered from soapstock represent a several billion pound resource. Coconut oil is imported to the extent of 700-1,000 million pounds per year. Its uses are divided about equally between edible and industrial applications. Safflower oil has a relatively small production, but 15–25% of the oil goes into industrial products. Soybean oil, the major edible oil of the world, is produced in the United States at the rate of 11,000 million pounds per year with more than 500 million pounds going into industrial uses, representing 5% of the total production. Castor oil is imported to the extent of about 100 million pounds per year. Linseed oil production has declined drastically over the last 25 years but still amounts to about 100 million pounds per year. Oiticica and tung oils are imported in lesser amounts than castor and linseed oils. New crops that have industrial potential, as well as the traditional vegetable oil crops, include seed oils from crambe,Limnanthes, Lesquerella, Dimorphotheca, Vernonia, andCuphea plants. Crambe oil contains up to 65% erucic acid. Oil fromLimnanthes contains more than 95% of fatty acids above C₁₈.Lesquerella oil contains hydroxy unsaturated acids resembling ricinoleic acid from castor oil.Dimorphotheca oil contains a conjugated dienol system.Vernonia oils contain as much as 80% epoxy acids. TheCuphea oils contain a number of short chain fatty acids. Of these, crambe,Limnanthes, andVernonia are probably the most developed agronomically. Competition between vegetable oils and petrochemicals for the traditional fats and oil markets has been marked over the past 25 years, but prices for petrochemicals have accelerated at a greater rate than those for vegetable oils; and, it is now appropriate to reexamine the old as well as the new markets for fatty acids.     

Agricultural and genetic potentials of cruciferous oilseed crops

Oilseed crops of the Cruciferae are widely adapted and are of particular importance to countries in the northern latitudes. Cruciferous seed oils from the crops, rapeseed, mustard, Camelina, oilseed radish and Crambe, enter edible or industrial markets, or both. The oil-seed meal can be used either as a high protein feed supplement or as an organic fertilizer. The spring and winter forms of the two species of rapeseed,Brassica napus andB. campestris, are commercially the most important. Advances in crop management and plant breeding have resulted in a 40% to 50% increase in seed yield over the past 25 years. In the next 10 to 15 years, application of newer plant-breeding techniques will result in varieties even higher in yield and seed with improved oil and meal quality. Some of the quality improvements will be new patterns in fatty acid composition, higher oil and protein content, lower fiber content, and removal of the undesirable glucosinolate compounds from the meal. The mustard cropsBrassica juncea andB. hirta are important condiment crops which have considerable potential as edible oil sources. Oilseed radish,Raphanus sativus, yields significantly less seed and oil than other cruciferous oil crops but its oil, which contains a low level of erucic acid (3.7%) and a relatively high content of 16-carbon fatty acids (9.3%), may be useful in blending with normal or zero erucic acid rapeseed oils.Camelina sativa or false flax has many desirable agronomic characteristics but the oil of camelina seed contains too high a level of linolenic acid (36%) to penetrate the edible oil market and too low to compete industrially with linseed oil.Crambe abyssinica andC. hispanica are potentially important producers of high erucic acid industrial oils. Factors limiting Crambe development are the high cost of seed transportation due to the high volume to weight ratio of the threshed seed and the need for extra seed processing steps to render the meal suitable as a high protein feed supplement for livestock and poultry. One of 9 papers presented at the Symposium, “Cruciferous Oilseeds,” ISF-AOCS World Congress, Chicago, September 1970. Contribution No. 425, Research Station, Canada Department of Agriculture, Saskatoon, Saskatchewan, Canada.     

Replacing fossil oil with fresh oil – with what and for what?

Industrial chemicals and materials are currently derived mainly from fossil‐based raw materials, which are declining in availability, increasing in price and are a major source of undesirable greenhouse gas emissions. Plant oils have the potential to provide functionally equivalent, renewable and environmentally friendly replacements for these finite fossil‐based raw materials, provided that their composition can be matched to end‐use requirements, and that they can be produced on sufficient scale to meet current and growing industrial demands. Replacement of 40% of the fossil oil used in the chemical industry with renewable plant oils, whilst ensuring that growing demand for food oils is also met, will require a trebling of global plant oil production from current levels of around 139 MT to over 400 MT annually. Realisation of this potential will rely on application of plant biotechnology to (i) tailor plant oils to have high purity (preferably >90%) of single desirable fatty acids, (ii) introduce unusual fatty acids that have specialty end‐use functionalities and (iii) increase plant oil production capacity by increased oil content in current oil crops, and conversion of other high biomass crops into oil accumulating crops. This review outlines recent progress and future challenges in each of these areas. Practical applications: The research reviewed in this paper aims to develop metabolic engineering technologies to radically increase the yield and alter the fatty acid composition of plant oils and enable the development of new and more productive oil crops that can serve as renewable sources of industrial feedstocks currently provided by non‐renewable and polluting fossil‐based resources. As a result of recent and anticipated research developments we can expect to see significant enhancements in quality and productivity of oil crops over the coming decades. This should generate the technologies needed to support increasing plant oil production into the future, hopefully of sufficient magnitude to provide a major supply of renewable plant oils for the industrial economy without encroaching on the higher priority demand for food oils. Achievement of this goal will make a significant contribution to moving to a sustainable carbon‐neutral industrial society with lower emissions of carbon dioxide to the atmosphere and reduced environmental impact as a result.     

Component fatty acids and composition of some oils and fats

Nineteen different samples of oils and fats have been examined for their component acids and composition by gas-liquid chromatography. Under programmed-temperature operations, the temperatures at which different components start to elute bear a straight-line relationship with their respective carbon numbers. Chromatograms, under programmed-temperature conditions, of methyl esters from such oils as coconut, groundnut, mustard, etc., are used for identifying the components of an unknown oil by comparing its chromatogram taken under nearly identical conditions. For confirmatory identifications, such plots as logarithm of retention times versus carbon numbers for saturated acids (14:0 to 24:0), monoenoic acids (14:1 to 24:1), and dienoic acids (18:2 to 24:2), under isothermal conditions, have also been used. Some new fatty acids, noted for the first time in traditional oils, are 15:0 in cottonseed oil, 20:1 in sesame oil, 22:0 in soybean oil, and 24:2 in mustard oil. Odd-carbon chain acids from 11∶0 to 23:0 have been observed in such vegetable oils as peanut germ, rice bran, andMesua ferrea. Fatty acid composition by GLC for new samples like peanut lecithin, peanut germ oil,Myristica attenuata, Myristica kanarica, Myristica magnifica, Mesua ferrea, Vateria indica, Schleichera trijuga, and shark-liver stearine are presented. Industrial utilization of these new oils and fats is discussed.     

The thermal cracking of soybean/canola oils and their methyl esters

Triacyl glycerides (TGs) are naturally occurring oils produced by a significant variety of crops, microorganisms (bacteria and algae), and animals (certain fats). The diversity and prevalence of the sources of these compounds suggest that they may serve as an attractive alternative to crude oil as the feedstock for the production of transportation fuels and certain industrial chemicals — organic compounds with carbon chain lengths in the range of C₇ to C₁₅. In the present study a series of batch thermal cracking reactions was performed using soybean oil and canola oil under reaction conditions leading towards attractive yields of potentially valuable (as fuels and/or chemicals) shorter chain products. An attractive yield of alkanes and fatty acids (from oil cracking) or esters (from biodiesel) was obtained. From a parametric study reaction temperature, followed by residence time, was found to have the most significant effect. Significantly, cracking under increased pressures in a hydrogen atmosphere did not improve the yields of desirable species.     

Epoxidation ofLesquerella andLimnanthes (Meadowfoam) oils

Lesquerella gordonii (Gray) Wats andLimnanthes alba Benth. (Meadowfoam) are species being studied as new and alternative crops. Triglyceride oil from lesquerella contains 55–60% of the uncommon 14-hydroxy-cis-11-eicosenoic acid. Meadowfoam oil has 95% uncommon acids, includingca. 60%cis-5-eicosenoic acid. Both oils are predominantly unsaturated (3% saturated acids), and have similar iodine values (90–91), from which oxirane values of 5.7% are possible for the fully epoxidized oils. Each oil was epoxidized withm-chloro-peroxybenzoic acid, and oxirane values were 5.0% (lesquerella) and 5.2% (meadowfoam). The epoxy acid composition of each product was examined by gas chromatography of the methyl esters, which showed that epoxidizedL. gordonii oil contained 55% 11,12-epoxy-14-hydroxyeicosanoic acid, and epoxidized meadowfoam oil contained 63% 5,6-epoxyeicosanoic acid, as expected for normal complete epoxidation. Mass spectrometry of trimethylsilyloxy derivatives of polyols, prepared from the epoxidized esters, confirmed the identity of the epoxidation products and the straightforward nature of the epoxidation process. Synthesis and characterization of these interesting epoxy oils and derivatives are discussed.     

The triglyceride composition,structure, and presence of estolides in the oils ofLesquerella and related species

Members of the genusLesquerella, native to North America, have oils containing large amounts of hydroxy fatty acids and are under investigation as potential new crops. The triglyceride structure of oils from twenty-fiveLesquerella species in the seed collection at our research center has been examined after being hydrolysis-catalyzed by reverse micellar-encapsulated lipase and alcoholysis-catalyzed by immobilized lipase. These reactions, when coupled with supercritical-fluid chromatographic analysis, provide a powerful, labor-saving method for oil triglyceride analysis. A comprehensive analysis of overall fatty acid composition of these oils has been conducted as well.Lesquerella oils (along with oils from two other Brassicaceae:Physaria floribunda andHeliophilia amplexicaulis) have been grouped into five categories: densipolic acid-rich (Class I); auricolic acid-rich (Class II); lesquerolic acid-rich (Class III); an oil containing a mixture of hydroxy acids (Class IV); and lesquerolic and erucic acid-rich (Class V). The majority of Class I and II triglycerides contain one or two monoestolides at the 1- and 3-glycerol positions and a C₁₈ polyunsaturated acyl group at the 2-position. Most Class III and IV oil triglycerides contain one or two hydroxy acids at the 1- and 3-positions and C₁₈ unsaturated acid at the 2-position. A few of the Class III oils have trace amounts of estolides. The Class V oil triglycerides are mostly pentaacyl triglycerides and contain monestolide and small amounts of diestolide. Our triglyceride structure assignments were supported by¹H nuclear magnetic resonance data and mass balances.     

How can we genetically engineer oilseed crops to produce high levels of medium‐chain fatty acids?

The end products of fatty acid synthase activities are usually 16‐ and 18‐carbon fatty acids. There are however, several plant species that store 8‐ to 14‐carbon (medium‐chain) fatty acids in their oil seeds. Among the medium‐chain fatty acids (MCFA), caprylic (8:0) and capric (10:0) are minor components of coconut oil, which are used in many industrial, nutritional and pharmaceutical products. Engineering crop plants such as Brassica could provide an economical source of these oils. During the last decade many laboratories have identified, cloned and characterized both the biosynthetic and catabolic enzymes regulating the composition and levels of these unusual fatty acids in seed oil. Among the biosynthetic enzymes thioesterases (TE), β‐ketoacyl‐ACP synthases (KAS) and acyltransferases are best characterized. In fact several independent investigators have shown that combined expression of the medium‐chain specific enzymes, specifically, TE, KAS and lysophosphatidic acid acyltransferase (LPAAT) results in the production of significant levels of MCFA in seed that otherwise do not accumulate any medium‐chain fatty acid. However, any additional increase in the levels of MCFA in transgenic seeds will require further detailed studies, such as possible induction of the medium‐chain specific enzymes in β‐oxidation and the glyoxylate pathways. To examine such a possibility, a number of genes involved in the β‐oxidation cycle among them a novel enzyme now designated as ACX3, a medium‐chain specific acyl‐CoA‐oxidase, has also been cloned. This article is an attempt to summarize our current knowledge and the present status of engineering oilseed crops for production of medium‐chain fatty acids.     

Single-Cell Oils as a Source of Omega-3 Fatty Acids: An Overview of Recent Advances

Omega-3 fatty acids, namely docosahexaenoic acid and eicosapentaenoic acid, have been linked to several beneficial health effects (i.e. mitigation effects of hypertension, stroke, diabetes, osteoporosis, depression, schizophrenia, asthma, macular degeneration, rheumatoid arthritis, etc.). The main source of omega-3 fatty acids is fish oil; lately however, fish oil market prices have increased significantly. This has prompted a significant amount of research on the use of single-cell oils as a source of omega-3 fatty acids. Some of the microbes reported to produce edible oil that contains omega-3 fatty acids are from the genus Schizochytrium, Thraustochytrium and Ulkenia. An advantage of a single cell oil is that it usually contains a significant amount of natural antioxidants (i.e. carotenoids and tocopherols), which can protect omega-3 fatty acids from oxidation, hence making this oil less prone to oxidation than oils derived from plants and marine animals. Production yields of single cell oils and of omega-3 fatty acids vary with the microbe used, with the fermentative growing conditions, and extractive procedures employed to recover the oil. This paper presents an overview of recent advances, reported within the last 10 years, in the production of single cell oils rich in omega-3 fatty acids.     

Whole-plant oils,potential new industrial raw materials

In an extensive screening program, 14 plant species have been identified which have good potential as hydrocarbon- and rubber-producing crops. These plants contain from 5 to 10% oil plus polymeric hydrocarbon on a dry weight basis. Since their dry matter yield should be 11,200 to 22,400 kg/ha/year, they would produce several times as much oil as conventional oilseed crops. In these plants, the oil is not concentrated in storage organs, i.e., seed or fruit tissue, but is distributed throughout the whole plant. Several species are lactiferous, with oil as a major component of the latex. A few which are of primary interest as potential new sources of natural rubber produce an equal yield of by-product oil. A prominent feature of most whole-plant oils is their large component of nonglyceride esters. Such oils could become valuable new feedstocks for production of plasticizers for rubber and plastics and new sources of waxes, long chain alcohols, sterols, terpenes, fatty acids, and other products. A petroleum refinery could be operated on whole-plant oils, and some species are being referred to as potential “gasoline trees.” Presented at the AOCS Meeting, St. Louis, May 1978.     

Fatty acid composition of seed oils of some members of the meliaceae and combretaceae families

Seed oils of some members of the Meliceae (six) and Combretaceae (three) were analyzed for their fatty acid composition. In oils of members of both families palmitic acid was the most abundant saturated acid. Trace amounts of short chain (C12–C14) and long chain (C20–C22) saturated acids were detected in some members of the two families. Oleic acid was the most abundant unsaturated acids in the oils of four members of the Meliaceae. However, in the oils ofCedrella odorata andLovoa trichilloides, dienoic acid (C18:2) was the major unsaturated acid. Strikingly high levels of trienoic (C18:3) and monoenoic (C16:1) acids were detected in the seed oils ofC. odorata andEnthandrophragma angolense, respectively. Oleic acid also was the most abundant unsaturated acid in the Combretaceae. The nutritional value and industrial potentials of these oils are given.     

Effect of extraction systems on the quality of virgin olive oil

Research has been carried out to ascertai the effects of different processing systems on olive oil quality. Tests were performed in industrial oil mills that were equipped with both pressure and centrifugation systems. Results show that oils extracted from good-quality olives do not differ in free fatty acids, peroxide value, ultraviolet absorption and organoleptic properties. Polyphenols ando-diphenols contents and induction times are higher in oils obtained from good-quality olives by the pressure system because it does not require addition of water to the olive paste. The centrifugation system requires the addition of warm water to the olive paste and helps to obtain oils with a lower content of natural antioxidants. Oils obtained from poorquality or from ripe olives in continuous centrifugal plants are lower in free fatty acids than those obtained by the pressure system. Dr. Mario Solinas is deceased—May 23, 1993.     

Process optimization for biodiesel production from Jatropha, Karanja and Polanga oils

Petroleum sourced fuels is now widely known as non-renewable due to fossil fuel depletion and environmental degradation. Renewable, carbon neutral, transport fuels are necessary for environmental and economic sustainability. Biodiesel derived from oil crops is a potential renewable and carbon neutral alternative to petroleum fuels. Chemically, biodiesel is monoalkyl esters of long chain fatty acids derived from renewable feed stock like vegetable oils and animal fats. It is produced by transesterification in which, oil or fat is reacted with a monohydric alcohol in presence of a catalyst. The process of transesterification is affected by the mode of reaction condition, molar ratio of alcohol to oil, type of alcohol, type and amount of catalysts, reaction time and temperature and purity of reactants. In the present paper various methods of preparation of biodiesel from non-edible filtered Jatropha (Jatropha curcas), Karanja (Pongamia pinnata) and Polanga (Calophyllum inophyllum) oil have been described. Mono esters (biodiesel) produced and blended with diesel were evaluated. The technical tools and processes for monitoring the transesterification reactions like TLC, GC and HPLC have also been used.     

Acylglycerol structure of genetic varieties of peanut oils of varying atherogenic potential

Detailed investigation was made of the triacylglycerol structure of three varieties of peanut oils of varying atherogenic activity. By means of chromatographic and stereospecific analyses, it was shown that all the oils had markedly nonrandom enantiomeric structures with the long chain saturated fatty acids (C₂₀−C₂₄) confined exclusively to thesn-3-position, whereas the palmitic and oleic acids were distributed about equally between thesn-1-andsn-3-positions, with the linoleic acid being found preferentially in thesn-2-position. On the basis of detailed studies of the molecular species of the separatesn-1,2-,sn-2,3- andsn-1,3-diacylglycerol moieties, it was concluded that the fatty acids in the three positions of the glycerol molecule are combined with each other solely on the basis of their relative molar concentrations. As a result, it was possible to calculate the composition of the molecular species of the peanut oil triacylglycerols (including the content of the enantiomers and the reverse isomers) by means of the 1-random 2-random 3-random distribution. In general, the three peanut oils possessed triacylglycerol structures which where closely similar to that derived earlier for a commercial peanut oil of North American origin. Since their oil has exhibited a high degree of atherogenic potential, it was anticipated that the present oils would likewise be atherogenic, which has been confirmed by biological testing. However, there are certain differences in the triacylglycerol structures among these oils, which can be correlated with the variations in their atherogenic activity. The major differences reside in the linoleic/oleic acid ratios in the triacylglycerols, especially in thesn-2-position, and in the proportions in which these acids are combined with the long chain fatty acids. On the basis of the characteristic structures identified in the earlier analyzed atherogenic peanut oil, the peanut oil of South American origin would be judged to possess the greatest atherogenic potential and this has been borne out by biological testing.     

The production of fish oils enriched in polyunsaturated fatty acid-containing triglycerides

A simple concentration technique was developed and used for the production of fish oils highly enriched with respect to the polyunsaturated triglycerides. The method involves the rapid solidification of fish oil droplets in liquid nitrogen followed by extraction with acetone at −60°C. The combined percentage ofcis-5,8,11,14,17-eicosapentaenoic acid (20:5) andcis-4,7,10,13,16,19-docosahexaenoic acid (22:6) after enrichment of a crude South African Anchovy (Engraulis capensis) oil was 57.4. A maximum percentage of 66.0 was attained for n-3 fatty acids after enrichment of a crude Chilean fish oil. A maximum yield of 26.0% was achieved for a crude sardine (Sardina pilchardus) oil. Triglycerides containing only saturated fatty acids or a combination of saturated and monoenoic acids were totally removed by the process, as assessed by silver-ion high-performance liquid chromatography of the triglyceride oils. This process permits the production of significant quantities of highly unsaturated triglycerides, which may be used in physiological and oxidative studies or for structural analysis of these triglycerides, many of which are present at extremely low concentrations in the original oils.     

Isovaleroyl triglycerides from the blubber and melon oils of the beluga whale (Delphinapterus leucas)

The fatty acid compositions of the blubber and melon oils from the beluga whale (Delphinapterus leucas) have been determined by gas liquid chromatography (GLC). The melon oil contains a high level (60.1 mole %) of isovaleric acid, substantial amounts of long chain branched acids (16.9%), and very little polyunsaturated material (0.5%). The blubber oil contains less isovaleric (13.2%), fewer long chain branched acids (2.7%), and appreciable amounts (10.9%) of the polyunsaturated acids typical of marine oils. The blubber and melon oils were also examined for lipid class composition by thin layer chromatography on silicic acid, direct GLC of the hydrogenated oil, and gel permeation chromatography. Both oils are composed almost entirely of triglycerides, which can be separated chromatographically into molecules containing 0, 1 and 2 isovaleric acid moieties. No triisovalerin could be detected. The blubber oil contains 68.9 mole % normal triacyl-, 24.2% diacyl-monoisovaleroyl-, and 7.0% monoacyl-diisovaleroyl-triglycerides (acyl=long chain acid). Monoacyl-diisovalerin constitutes 86.7 mole % of the melon oil. This unusual compound may play a role in the echolocation system of the beluga whale.     

Selection for Some Olive Oil Quality Components Through the Analysis of Fruit Flesh

Selection for oil quality is commonly conducted at the latest stages of olive breeding programs, as oil quality traits are measured in extracted oils. At the initial stages of breeding, the number of genotypes is high and fruit production is low, which makes it difficult to conduct oil extraction. The objective of this research was to evaluate the feasibility of conducting selection for some important oil quality traits in olive by analyzing fruit flesh instead of extracted oils. Fatty acids, tocopherols, phytosterols, and squalene were measured in fruit flesh and extracted oils from 22 individual olive trees showing variability for oil quality traits. Correlation coefficients between analyses conducted on fruit flesh and extracted oils were r = 0.98 for the main fatty acids palmitic, oleic, and linoleic acid, r = 0.96 for tocopherol content, r = 0.89 for phytosterol content, r = 0.97 for squalene content, and r = 0.91 and 0.94 for the concentrations of the two main sterols β-sitosterol and Δ⁵-avenasterol, respectively. The results revealed that selection for the mentioned oil quality traits can be efficiently conducted through the analysis of fruit flesh instead of extracted oil, which facilitates selection on larger numbers of genotypes at the initial stages of olive breeding programs.     

Engineering Oilseed Plants for a Sustainable,Land-Based Source of Long Chain Polyunsaturated Fatty Acids

Numerous clinical studies have demonstrated the cardiovascular and mental health benefits of including very long chain omega-3 polyunsaturated fatty acids, namely eicospentaenoic acid (EPA) and docosohexaenoic acid (DHA) in the human diet. Certain fish oils can be a rich source of omega-3 long chain polyunsaturated fatty acids although processed marine oils are generally undesirable as food ingredients because of the associated objectionable flavors and contaminants that are difficult and cost-prohibitive to remove. Oilseed plants rich in omega-3 fatty acids, such as flax and walnut oils, contain only the 18-carbon omega-3 polyunsaturated fatty acid alpha-linolenic acid, which is poorly converted by the human body to EPA and DHA. It is now possible to engineer common omega-6 rich oilseeds such as soybean and canola to produce EPA and DHA and this has been the focus of a number of academic and industrial research groups. Recent advances and future prospects in the production of EPA and DHA in oilseed crops are discussed here.