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Industrial uses of vegetable oils
Editor Sevim Z. Erhan Food and Industrial Oil Unit National Center for Agricultural Utilization Research Agricultural Research Service United States Department of Agriculture Peoria, IL 61804 Champaign, Illinois Industrial Uses of Vegetable Oils IndustOils (FM)(i-vii)Final 3/23/05 6:00 PM Page 1 Copyright © 2005 AOCS Press AOCS Mission Statement To be the global forum for professionals interested in lipids and related materials through the exchange of ideas, information science, and technology. AOCS Books and Special Publications Committee M. Mossoba, Chairperson, U.S. Food and Drug Administration, College Park, Maryland R. Adlof, USDA, ARS, NCAUR, Peoria, Illinois P. Dutta, Swedish University of Agricultural Sciences, Uppsala, Sweden T. Foglia, ARS, USDA, ERRC, Wyndmoor, Pennsylvania V. Huang, Abbott Labs, Columbus, Ohio L. Johnson, Iowa State University, Ames, Iowa H. Knapp, Deanconess Billings Clinic, Billings, Montana D. Kodali, Global Agritech, Inc., Plymouth, Minnesota T. McKeon, USDA, ARS, WRRC, Albany, California R. Moreau, USDA, ARS, ERRC, Wyndoor, Pennsylvania A. Sinclair, RMIT University, Melbourne, Victoria, Australia P. White, Iowa State University, Ames, Iowa R. Wilson, USDA, REE, ARS, NPS, CPPVS, Beltsville, Maryland Copyright (c) 2005 by AOCS Press. All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means without written permission of the publisher. The paper used in this book is acid-free and falls within the guidelines established to ensure permanence and durability. Library of Congress Cataloging-in-Publication Data Industrial uses of vegetable oils / editor, Sevim Z. Erhan. p. cm. Includes index. ISBN 1-893997-84-7 1. Vegetable oils Industrial applications. I. Erhan, Sevim Z. TP680.I555 2005 665'.384 dc22 2005007927 Printed in the United States of America. 08 07 06 05 04 5 4 3 2 1 IndustOils (FM)(i-vii)Final 3/23/05 6:00 PM Page 2 Copyright © 2005 AOCS Press iii Preface Vegetable oils are used in various industrial applications such as emulsifiers, lubri- cants, plasticizers, surfactants, plastics, solvents and resins. Research and develop- ment approaches take advantage of the natural properties of these oils. Vegetable oils have superb environmental credentials, such as being inherently biodegradable, having low ecotoxicity and low toxicity towards humans, being derived from renewable resources, and contributing no volatile organic chemicals. United States agriculture produces over 25 billion pounds of vegetable oils annually. These domestic oils are extracted from the seeds of soybean, corn, cotton, sunflower, flax, and rape. Although a major part of these oils are used for food prod- ucts such as shortenings, salad and cooking oils and margarines, large quantities serve feed and industrial applications. Other vegetable oils widely used industrially include palm, palm kernel, coconut, castor, and tung. However, these are not of domestic origin. The three domestic oils most widely used industrially are soybean, linseed from flax, and rapeseed. Nonfood uses of vegetable oils have grown little during the past 40 years. Although some markets have expanded or new ones added, other markets have been lost to competitive petroleum products. Development of new industrial products or commercial processes is the objective of continued research in both public and pri- vate interests. The following selected examples illustrate progress in identifying and developing new technologies based on vegetable oils. Great progress has been made in understanding of the biochemical basis for biosynthesis of oils containing fatty acids. This biochemical information is in turn used to identify and isolate genes that are needed to make these oils. By genetical- ly engineering the introduction and expression of these genes, domesticated crops that can produce these potentially useful fatty acids have been engineered and are continuing to be developed to produce an ever wider range of novel oils. Chapter 1 explains the biochemical changes that can be introduced to alter fatty acid composition. It also discusses industrial oils that have been developed through genetic engineering, as well as some that have been developed on the laboratory scale, but have not yet been introduced commercially. Recent environmental awareness and depletion of world fossil fuel reserves have forced to look a substitute for mineral oils with the biodegradable fluids such as vegetable base oils and certain synthetic fluids in grease formulations. The non- toxic and readily biodegradable characteristics of vegetable oil based greases pose less danger to soil, water, flora, and fauna in case of accidental spillage or during disposal. Biodegradable greases are particularly useful in open lubrication systems where the lubricant is in direct contact with environment, and total loss lubricants like railroads, where immediate contact with the environment is anticipated. Chapter 2 discusses the various components (base oils, thickeners and additives), functional properties, and characteristics of biodegradable greases. The base oils included syn- thetic esters, castor, rapeseed, and soybean oil. IndustOils (FM)(i-vii)Final 3/23/05 6:00 PM Page 3 Copyright © 2005 AOCS Press Chapter 3 reviews some of the advantages and disadvantages of using vegetable oil lubricants and their availability. Some of the history in the development of veg- etable-based engine oils and their current status is described. The requirements for further development and penetration of the petroleum based engine oil market are discussed. Besides transesterification to alkyl esters, three other approaches—dilution with conventional, petroleum-based diesel fuel, microemulsions (co-solvent blending), and pyrolysis—have been explored for utilizing vegetable oils as fuel. However, as the mono-alkyl esters of vegetable oils and animal fats—biodiesel—are the only approach that has found widespread use (and, accordingly, the vast majority of research papers deal with this approach), Chapter 4 focuses on such mono-alkyl esters in terms of use, properties, economies, and regulatory issues. Chapter 5 presents a background on home heating systems and highlights recent research to develop renewable biofuels for home heating applications. Petroleum- based liquid home heating oil is used to heat over 8 million homes in the U.S., pre- dominantly in the northeastern U.S. This comprises approximately 6.6 billion gal- lons of fuel oil annually. With recent rises in petroleum prices to over $50 per bar- rel and anticipated future price increases as petroleum resources become less avail- able, many applications that depend on petroleum are searching for alternatives. Additional concerns over environmental issues involving sulfur and nitrogen oxide emissions from oil-based home heating systems have sparked a search for alterna- tive fuels to supply this market. Polyurethanes are the most versatile group of polymers which can be used in the form of foams, cast resins, coatings, adhesives and sealants. Polyols used in the polyurethane industry currently exceed 2.4 million tons/year in the U.S. To use nat- ural oils as raw materials for polyurethane production, multiple hydroxyl function- ality is required. Castor oil has hydroxyl functionality naturally built in, thus it has received extensive exploration as polyurethane building blocks, such as casting resins, elastomers, urethane foams, and interpenetrating networks. Hydroxyl func- tionality can be introduced synthetically in other natural oils. This process involves a number of approaches and has been studied extensively by scientists around the world, but commercial production of oil-based polyols has been scarce. Chapter 6 discusses the four main approaches for the hydroxylation of vegetable oils. In Chapter 7, the authors summarize the type of natural composites reinforced with different fibers along with different composite molding methods. The Solid Freeform Fabrication Method and its advantages are included in the discussion. Technologies that have improved the use of oils in coatings are highlighted in Chapter 8. The petroleum shortage in the 1970s stimulated research on vegetable oil-based inks as a substitute for petroleum based products. Vegetable oils are mainly used in paste inks; therefore the role of vegetable oils in the paste ink formulations and their environmental properties are the main subject of Chapter 9. Chapter 10 explains that vegetable oils provide a renewable source of fatty acids that can serve as raw materials for the production of numerous surfactant com- pounds. Structural modification of the fatty acids can impart unique physical prop- iv Preface IndustOils (FM)(i-vii)Final 3/23/05 6:00 PM Page 4 Copyright © 2005 AOCS Press Preface v erties that alter the performance of the product in a predictable manner. Chemical functionality can be introduced at the carbonyl carbon or along the carbon chain by appropriate selection of reactants, catalysts, and reaction conditions. A tremendous diversity of products is available with these oleochemical substrates. In addition, vegetable oils provide a favorable alternative to petrochemical feedstocks. The editor of this timely publication thanks the authors and their organizations for their technical contributions in the chapters of this book. A special thanks goes to Brittney Mernick for her assistance in the preparation of chapters for publication. Sevim Z. Erhan February 14, 2005 IndustOils (FM)(i-vii)Final 3/23/05 6:00 PM Page 5 Copyright © 2005 AOCS Press Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Chapter 1 Genetic Modification of Seed Oils for Industrial Applications Thomas A. McKeon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Chapter 2 Current Developments of Biodegradable Grease Atanu Adhvaryu, Brajendra K. Sharma, and Sevim Z. Erhan . . 14 Chapter 3 Vegetable Oil-Based Engine Oils: Are They Practical? Joseph M. Perez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Chapter 4 Biodiesel: An Alternative Diesel Fuel from Vegetable Oils or Animal Fats Gerhard Knothe and Robert O. Dunn . . . . . . . . . . . . . . . . . . . 42 Chapter 5 Biofuels for Home Heating Oils Bernard Y. Tao . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Chapter 6 Vegetable Oils-Based Polyols Andrew Guo and Zoran Petrovic . . . . . . . . . . . . . . . . . . . . . . . . 110 Chapter 7 Development of Soy Composites by Direct Deposition Zengshe S. Liu and Sevim Z. Erhan . . . . . . . . . . . . . . . . . . . . . 131 Chapter 8 Vegetable Oils in Paint and Coatings Michael R. Van De Mark and Kathryn Sandefur . . . . . . . . . . . 143 Chapter 9 Printing Inks Sevim Z. Erhan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 Chapter 10 Synthesis of Surfactants from Vegetable Oil Feedstocks Ronald A. Holser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 Contents vii vii IndustOils (FM)(i-vii)Final 3/23/05 6:00 PM Page 7 Copyright © 2005 AOCS Press 1 Chapter 1 Genetic Modification of Seed Oils for Industrial Applications Thomas A. McKeon USDA, ARS, WRRC, Albany, CA 94710 Introduction While most vegetable oils are produced for food and feed uses, up to 15% of soy (as well as other food oils) and up to 100% of certain commodity oils are used for industrial purposes. Most food oils, such as soybean or canola, are composed pri- marily of five fatty acids (FA): palmitic, stearic, oleic, linoleic, and linolenic; these oils are used to produce surfactants, lubricants, inks, coatings, and polymers. Commodity oils containing uncommon FA, such as castor (90% 12-hydroxy- oleate) and tung (up to 80% conjugated FA), have no nutritive value, but due to the unusual properties of the FA, they prove very useful for industrial applications. It is the chemical functionality of a vegetable oil that can make it useful to industry; chemical functionality can alter physical properties or allow chemical precursors or useful derivatives to be made. For example, ricinoleate, the FA from castor oil, has a mid-chain hydroxyl group that enhances its viscous properties for use as grease and also enables production of an extensive range of chemical derivatives (1). Coconut oil contains laurate (12:0) which has excellent foaming properties and is used to make anionic surfactants. Hydroformylation of petroleum provides an equivalent surfactant (2). The possibility of replacing such petroleum products with plant-derived FA is a major goal of seed oil utilization research. There are hundreds of FA with unusual functionalities, at least some of which would have immediate application if readily available from a suitable crop. To the extent that uncommon FA are produced in a given plant, these are a result of evolu- tion, perhaps providing selective advantage as a result of toxic or other protective effects of the FA on pathogens. Though it operates on a long time scale, evolution has provided an unusual array of genetic material for production of useful FA. However, many of these FA are produced in plants that are unsuitable as crops. Traditional breeding techniques can alter levels of FA present in the oil and, with suitable germ plasm, can reduce or eliminate one or more of the FA normally present, as was the case in the development of canola (low-erucic acid rapeseed) (3,4). Breeding has been used to develop plant selections with a high proportion of a single component, e.g., such as high oleic safflower. High enrichment of a single component such as oleate represents another industrially useful feature, as it Ch1(IndOils)(1-13)Final 3/23/05 6:12 PM Page 1 Copyright © 2005 AOCS Press 2 T.A. McKeon reduces the expense of purifying the desired component. But breeding cannot be used to introduce a FA not already present in one of the crossed plants. Random mutagene- sis using chemical or radiation agents to alter the genome followed by screening and breeding has also produced varieties with altered FA composition in oil (5). Genetic identification and chemical characterization of FA biosynthetic mutants in mutated Arabidopsis thaliana has provided an extensive genetic map of FA and lipid biosyn- thetic steps during plant growth and development (6), in many cases providing null mutants lacking a specific enzymatic activity. Since the mutagenic approach is geared toward eliminating genes, this approach has been used as part of breeding programs to reduce levels of undesirable FA components such as high polyunsatu- rates from linseed oil (7) or to increase levels of a desired FA, e.g., oleate in sun- flower by eliminating the enzyme that normally converts it to linoleate (8). A recent innovation in this approach is TILLING (Targeting Induced Local Lesions IN Genomes), which uses a mutagenic approach, but introduces high-throughput screening of the M 2 generation (the second generation of self-pollinated, mutated lines) in order to identify specific genes that have been altered or inactivated by mutagenic events (9). Plant selections carrying these mutated genes can then be screened directly for desired characteristics. The TILLING process thus moves most of the screening effort into the laboratory, considerably reducing the popula- tion that would otherwise have to be grown in the field for phenotypic screening. With the advent of genetic engineering, the technology needed to introduce novel traits became available to breeders. A driving force behind development of genetically engineered oils is the perennial surplus of oils produced. The unused inventory of soy- bean oil may reach nearly two billion pounds in any year. Crops with altered oil com- position hold the promise of reducing or preventing annual inventory carryover, thus stabilizing or improving farm income. This chapter will explain the biochemistry underlying the alteration of FA composition, briefly describe some oils that have been developed through genetic engineering and mention some of the “target” FA of inter- est for production in transgenic oilseed crops. FA Biosynthesis FA biosynthesis in plants proceeds from acetylCoA, which initiates a set of condensa- tion reactions with malonyl-ACP through six or seven additional condensations with malonyl-ACP. This yields the saturated FA palmitate or stearate, respectively, as depicted in Figure 1.1, which depicts the pathway of FA biosynthesis to linoleic acid, with the reactions leading to palmitate, stearate, and oleate occurring in the plastid, separate from reactions leading to oil biosynthesis. Given the dependence of FA pro- duction on malonyl-CoA production (to provide malonyl-ACP), the acetyl-CoA car- boxylase (ACCase) is generally thought to play a regulatory role in FA production and oil biosynthesis (10). This hypothesis is supported by research in which ACCase from Arabidopsis was overexpressed in potato, leading to an increase in FA produc- tion and a fivefold increase in triacylglycerol levels in the tuber (11). Ch1(IndOils)(1-13)Final 3/23/05 6:12 PM Page 2 Copyright © 2005 AOCS Press Genetic Modification of Seed Oils 3 Fig. 1.1. The pathway of fatty acid biosynthesis to linoleic acid. Ch1(IndOils)(1-13)Final 3/23/05 6:12 PM Page 3 Copyright © 2005 AOCS Press 4 T.A. McKeon Medium Chain-Length FA Biosynthesis In seeds of certain plants such as coconut, palm kernel, bay laurel, and cuphea, the flow of carbon to the long-chain saturated FA is disrupted, and this occurs as the result of an acyl-ACP thioesterase (product of the FAT B gene), which removes the ACP from the elongating FA chain prior to achieving full length. This produces a medium chain-length FA which is transported from the plastid and enters the oil biosynthetic pathway. This approach copied from nature led to the development of the first transgenic oilseed modified to produce an industrial oil product, namely Laurate Canola (12). By inserting into Canola the cDNA for a medium-chain spe- cific acyl-ACP thioesterase (13) from California bay laurel, a plant which produces seeds containing >60% laurate(dodecanoate) in its oil, plastidial FA synthesis was diverted to the production of laurate, which was incorporated into the seed oil (14). Although this achievement was a key early success in the contribution of genetic engineering to agriculture, the underlying science also pointed to a number of tech- nical problems that have since been widely recognized. The production of a FA not normally produced by the seed may trigger a “counter-reaction.” In the case of lau- rate, considerable amounts of the laurate were β-oxidized, since the cytoplasmic lauroyl-CoA used to acylate glycerolipid is also an intermediate in β-oxidation (15,16). While increased carbon flux through the FA biosynthetic pathway enhanced laurate production, the overall outcome was a canola cultivar with reduced oil yield, since some of the carbon incorporated into laurate production was oxidized through the futile cycle. The laurate canola oil produced also lacked laurate in the sn-2 position of the triacylglycerol (TAG) (17). The canola seed lacked a lyso-phosphatidic acid acyl- transferase (LPAAT) that could use lauroyl-CoA as an acyl donor for the sn-2 position of glycerolipid. Researchers at Calgene solved this problem by crossing a canola plant containing an LPAAT gene from coconut (17), with a laurate canola plant (18). The resulting plant produced an oilseed in which laurate is distributed among all three positions of the TG. The resulting “High-Laurate Canola” had a laurate content of up to 70%. The successful design of a novel, temperate-climate industrial crop provided a great impetus to follow this approach for other industri- ally useful products, especially oils. It also provided a foreshadowing of the diffi- culties to be encountered in engineering production of uncommon FA in oilseeds. Monounsaturated FA Biosynthesis In general, once saturated FA are released from acyl-ACP, they are incorporated into oil without any apparent modification except, to a minor extent, elongation. In the plastid, though, the saturated fatty acyl-ACP can be desaturated by the ∆9- desaturase, a class of soluble enzymes (as opposed to membrane-bound) formerly identified as the stearoyl-ACP desaturase, which is the type present in most oilseeds. These enzymes share a considerable degree of amino acid sequence homology and the same type of active site in which the desaturation is carried out. Ch1(IndOils)(1-13)Final 3/23/05 6:12 PM Page 4 Copyright © 2005 AOCS Press [...]... The use of oils from genetically modified seeds has opened up several possibilities in the field of nonfood uses of vegetable oils DuPont has developed a genetically modified soybean that would produce soy oil with enhanced stability for a variety of industrial uses including application in grease making (21) Soap Thickeners Vegetable oil-based greases are semi-solid colloidal dispersions of a thickening... linoleic acid and linolenic acid or mixtures thereof Vegetable oils are a potential source of environmentally friendly base oils that have the additional advantage of not disturbing the global carbon dioxide equilibrium They exhibit excellent lubrication properties due to unbalanced electrical charges which make them attach to metal surfaces Vegetable oils that are extensively used for biodegradable... in the United States The farm value of soybean production in the crop year 2000 was $13 billion The 3.1 billion gallons of soybean oil produced in the United States is half of the 6.2 billion gallons produced worldwide Soy oil (typically 18% of the weight of the soybean) can be used in its raw or refined form in a variety of industrial products (fuels, inks, paints, industrial fluids, etc.) This oil... and development of new technologies for production of lubricants according to the most advanced, “ecological” trends The best approach seems to focus on alternative, renewable, widely available, natural resources, such as vegetable oils They are naturally occurring triacylglycerols that are formed by the reaction of one mole of glycerol with three moles of fatty acids or a mixture of fatty acids (Fig... structure of the soap phase in grease consists of crystallites, which take the form of fibers, this does not clearly explain why a small amount of a solid (soap) could immobilize a large volume of the base oil in grease These fiber structures form a complex network that traps the base oil molecules in two ways: (i) by direct sorption of the oil by polar ends of soap molecule, and (ii) penetration of base... primary goal of agricultural chemical producers that have initiated programs to produce GM crops Currently, the four genetically engineered crops that have been adopted are all oilseed crops: soy, corn, cotton and canola They account for 99% of transgenic crops planted Copyright © 2005 AOCS Press Ch1(IndOils)(1-13)Final 3/23/05 6:12 PM Page 9 Genetic Modification of Seed Oils 9 TABLE 1.1 Industrially... characterization, and cloning of unusual enzyme activities from plants that produce uncommon, industrially useful FA Hundreds of uncommon FA, with unusual chemical functionalities, are produced by one or more oilseed plants A considerable amount of research has gone into elucidating the biosynthetic process by which such FA are made; much of the enzymology underlying the introduction of unsaturation, conjugated... Dwivedi et al described the preparation of total vegetable oil-based grease using castor oil (9) Florea et al have studied the effect of different base fluids on the properties of biodegradable greases (10) A suitable composition of grease is desired with good performance properties capable of use in multifunctional products Despite the overwhelming importance of biodegradable greases, very little is... and Improved Crops The production of industrially useful FA in transgenic crops is complicated by the need for greater understanding of how such FA are efficiently made in the plants that make them, and how their incorporation into oil is directed Table 1.1 lists a number of FA and related products that are of interest to researchers seeking to expand the role of seed oils in the “hydrocarbon economy.”... interlacing structure of soap fiber The oil-retaining property of grease may be due to the attractive influence of soap fibers extending through many layers of the base oil molecule and not to the swelling of the fibers (25) Therefore, the physical and chemical behavior of grease is largely controlled by the consistency or hardness, which is dependent upon the microstructure of soap fibers Thus, a . durability. Library of Congress Cataloging-in-Publication Data Industrial uses of vegetable oils / editor, Sevim Z. Erhan. p. cm. Includes index. ISBN 1-893997-84-7 1. Vegetable oils Industrial applications most vegetable oils are produced for food and feed uses, up to 15% of soy (as well as other food oils) and up to 100% of certain commodity oils are used for industrial purposes. Most food oils, . However, these are not of domestic origin. The three domestic oils most widely used industrially are soybean, linseed from flax, and rapeseed. Nonfood uses of vegetable oils have grown little