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Fats in the SpotlightFats in the Spotlight

June 1, 1999

27 Min Read
Fats in the Spotlight

Food Product Design

Fats in the Spotlight
June 1999 -- Cover Story

By: Ann Juttelstad
Associate Technical Editor
and Lynn A. Kuntz

  Fats have long been the focus of scientific study, and are recognized as one of the building blocks of foods. They're an important part of the diet, necessary for the assimilation of vitamins and the growth of cells. Despite the health benefits of fats, however, there are hazards in the consumption of too much fat and the wrong types of fats. Science has established the relationship between excessive dietary fat and heart disease, stroke and increased levels of LDL ("bad") cholesterol, and much of the current research is geared to identify the types of fat that most put health at risk.All these considerations - the good, the bad and the ugly sides of fat - affect the way designers use fats and oils in food products.Chemistry classes  Fats, commonly known as triglycerides, are referred to chemically as triacylglycerols - esters derived from glycerol and three fatty acids. They are insoluble in water, but soluble in most organic solvents, such as diethyl ether, petroleum ether, chloroform or carbon tetrachloride. Triglycerides are composed primarily of fatty acids, about 95% of the total by weight. Edible fats are composed only of carbon, hydrogen and oxygen. Fats are less dense than water, and can be either liquid or solid at room temperature, depending on their chemical structure. It's common to use "fat" to describe triglycerides that are solid at room temperature, and "oil" for those that are liquid at room temperature, but the two terms are really interchangeable.  Most of the fatty acids found in nature are made up of an even number of carbon atoms in straight chains from 4 to 24, although there are a few straight-chain acids with odd numbers of carbon atoms and some branched or cyclic chains. The longer chain lengths tend to promote a higher melt point than shorter ones.   Fats are often referred to as saturated or unsaturated. This actually refers to the fatty acid structure. Saturated fatty acids contain one or more fatty acids in which the carbons are connected to each other only by single bonds, depicted as C-C. Saturation raises the melting point of a fat, so fats with higher saturate levels are generally solid at room temperature. Unsaturated fatty acids have double bonds, depicted as C=C, in the carbon chain. Fats with higher levels of unsaturates tend to be liquid at room temperature. Monounsaturated fatty acids have one double bond. Of the monounsaturates, oleic acid is the most common. Polyunsaturated fatty acids, such as linoleic acid, found in soybean oil, have more than one double bond in the carbon chain. Because of the double bonds, a higher level of unsaturated fatty acids makes fats more prone to oxidation and polymerization.  For labeling, the fatty acids are converted to triglyceride equivalents to arrive at percent saturated fat, monounsaturated, etc. Fats with high levels of a particular type of fatty acid are commonly referred to by that name (e.g. animal fats contain high levels of saturates and so are called saturated fats).  Reacting fat with hydrogen in the presence of a catalyst, usually nickel, forms a hydrogenated fat. Naturally occurring fatty acids usually have hydrogen atoms located on the same side of a double bond, which is called a cis isomer. Hydrogenation promotes the formation of trans arrangements, where some of the hydrogen atoms move to the opposite side of the double bond. Fully hydrogenated fats have no trans fatty acids because all of the carbons are bound to a hydrogen atom, and no double bonds remain to create that type of structure.  Because of the digestive process of cattle, tallow has up to 7% trans fatty acid, and butterfat and mutton fat also have small amounts of trans, but not nearly as much as hydrogenated shortenings. The major trans fatty acid in milk, butter and beef fat is vaccenic acid. "The trans produced from partial hydrogenation reside at different positions along the fatty acid backbone compared to naturally occurring trans in ruminants," notes Robert Wainwright, manager of technical sales, C&T Refinery, LLC, Charlotte, N.C.  Eliminating double bonds and forming trans isomers raises an oil's melting point, and can make it solid at room temperature, which provides texture and mouthfeel to products. Hydrogenation also increases process and storage stability. The amount of hydrogenation can be carefully controlled in production, providing food manufacturers with a wide range of hydrogenated fats of varying hardness, solid fat index (SFI) and application. Fats don't actually have a single melt point, they melt across a curve. The solid fat index is the percentage of fat that is solid at various temperatures. The SFI helps determine the way a solid or semi-solid (plastic) fat functions during processing.Fats in foods  Most of today's fats have evolved as a compromise between functionality and health. Manufacturers are looking for fats that are stable to oxidation and chemical breakdown, and that provide certain functional characteristics such as melt profiles and texture or consistency.  Shortenings, usually used as baking and frying fats, were formed in the past by blending animal fats with vegetable oils. Nowadays, most shortenings are made by hydrogenation of either a single vegetable fat, or more often, a vegetable-fat blend. Shortenings are so named because incorporating them in pastry dough makes the dough 'short,' or makes a pie crust tender. Shortenings provide structure in some products, such as cookie doughs. Creaming the shortening with sugar incorporates small air bubbles in the batter that act as nuclei for leavening gasses, providing the finished product with a fine texture. In puff pastries, plastic fat is layered onto the dough. This prevents adjacent dough layers from binding together during proofing and baking, resulting in a flaky, layered finished product. Hydrogenated shortenings also have high stability, or "kettle life," when used for frying.  Hard butters are designed to replace or extend cocoa butter or butterfat. Cocoa-butter alternatives typically are found in confectionery applications, while butterfat alternatives are used in vegetable and non-dairy products. In either case, hard butters possess steep melting profiles, clean flavor and excellent oxidative and flavor stability. They are derived from either offshore, or tropical, fats (palm kernel, coconut, palm) or domestic oils. Processing techniques for the production of hard butters include hydrogenation, interesterification and/or fractionation.  Blending fats with water, milk solids, flavoring, colorings and vitamins produces margarine. Stick margarines are designed to be solid at room temperature, and must be at least 80% fat, according to the Code of Federal Regulations. Imitation margarines must be 40% to 52% fat, while spreads contain 52% to 75% fat. The trans fatty acid content of margarines varies from 0% to about 30%, depending on consistency. Soft margarines run from 0% to up to 15% trans, since they contain more liquid vegetable oil, while stick margarines often have 15% to 30% trans, since they use hydrogenated fats to keep their shape and consistency. In Europe, some margarines are prepared from a mixture of liquid vegetable oil and saturated fats such as tropical oils, lard or beef tallow. They may contain some cholesterol and a higher level of saturated fat.  Butter, made from cow's milk, must contain not less than 80% by weight butterfat. Butterfat can contain up to 60 different fatty acids. On average the fat is comprised of 66% saturated, 30% monounsaturated and 4% polyunsaturated fatty acids, although this can vary with the season and the cow's feed. However, of the saturated fatty acids, only about two-thirds are C12 to C14, those most implicated in coronary disease.In transition  Fat consumption (of fat added to the diet, rather than consumed as part of meat or vegetable tissue) has dropped to around 65 lbs. per person per year, according to the Calorie Control Council. Along with this reduced fat consumption, consumers have developed an increased awareness of the types of fats they eat. Consumers have learned the connection between fat consumption and incidence of disease. "I'm watching my cholesterol" is a common phrase among the over-40 crowd. This has blossomed into a general move to eliminate saturated and unsaturated fats, tallow and butter from the American diet. The latest cry is to remove trans fats from the public table.  Recent studies have found that high levels of trans fats in the diet can contribute to coronary heart disease (CHD), myocardial infarction and possibly breast cancer, much as do saturated fats. Volumes of studies have been conducted in recent years on the effects of this fat in the diet, but until recently, their results made it difficult to determine what effect could be attributed to trans fats. However, current results do suggest that they have a negative effect on heart health. According to the American Heart Association, trans fatty acids tend to raise total blood cholesterol levels, but not to as high a degree as more saturated fatty acids. Trans fatty acids appear to raise LDL cholesterol and lower HDL ("good") cholesterol when used in place of cis fatty acids or oils. The Nurses' Health Study, which covered 14 years and over 80,000 women, linked trans fatty acids with CHD. After looking at actual food intake, the study suggested that trans fatty acids from partially hydrogenated vegetable oils used in margarine, cookies, cakes and white bread promoted an increased risk of CHD.  While many experts claim that the average amount of trans fatty acids in the American diet (the American Society for Clinical Nutrition and the American Institute of Nutrition estimate it to be between 2% and 4%) is not a concern, others are not so sure. In a letter published in The New England Journal of Medicine in December 23, 1993, researchers Lisa Litin, R.D., and Frank Sacks, M.D., from the Harvard School of Public Health, Boston, gave a hypothetical scenario that came to a total of 9.6 g of trans fatty acids consumed in a day. This was nearly 5% of the total energy intake of an 1800-calorie diet. This included a doughnut (3.19 g of trans fatty acids), a small order of french fries (3.43 g), two teaspoons of stick margarine (1.24 g), and two cookies (1.72 g). The authors wrote that: "This intake of trans fatty acids would be predicted to negate the serum cholesterol-lowering effect of a decrease in saturated fat of 10% of total energy intake." David Allison, Ph.D., and coworkers reported in the February, 1999 issue of Journal of the American Dietetic Association that "on average, the U.S. population consumes a mean of 5.3 g of trans fatty acids per day - about 2.6% of their total energy and 7.4% of their fat energy."  Manufacturers of shortening-dependent products, such as cookies, pastries and fried foods, are seeing the "signs on the wall" from all this trans talk. Trans fat labeling is coming, and it is coming soon, and along with it comes research, reformulating, redevelopment and redesigning of labels. Since the beginning of the trans controversy, activists in the food and medical communities have been petitioning to get processors to label these fats on their products. In fact, according to the April 26, 1999 Federal Register, the FDA "is proposing to amend its regulations to provide for the declaration of trans fatty acids in nutrition labeling, to add a requirement that prevents foods from bearing nutrient content claims for saturated fat (i.e., saturated fatty acids) and cholesterol if they contain trans fatty acids above a specified level, and to define a 'trans fatty acids free' nutrient content claim." The action date for this proposal is August of 1999.  "The industry is holding its' breath on trans labeling," says Willie Loh, marketing development for Cargill Foods, Vegetable Oil Division, Minneapolis. "But is it imminent." When news does come out, "it's going to be a reaction story," he says, with media jumping on it as is has with other health-related stories in recent years.Formulating without trans   In response to the trans tempest, suppliers have taken a lead position in developing replacement fats. Research continues to make these ingredients easier to use, more cost-effective and more functional. The good news, says Loh, is that the oil industry has started to develop reduced-trans technology, while getting their customers ready for the change. "Life is difficult enough as it is without having to reformulate," he says.  An example is how many foodservice operators have worked closely with their suppliers to improve the nutritional quality of their products, says Wainwright. When animal fats, with their high cholesterol and saturated-fat contents, were first implicated as causative factors in heart disease, fast-food providers began frying foods in hydrogenated vegetable oils.  "Animal fats were singled out as bad actors," says Wainwright, "and additional focus was brought to bear on saturates. Many went from animal or animal/vegetable blends to heavy-duty, all-vegetable plastic products. Robust fluid frying shortenings were developed and successfully replaced many of the more highly hydrogenated plastic shortenings. This development also significantly reduced the trans content, often in the neighborhood of 50% or more, since fluid frying systems are more unsaturated (less hydrogenated)."  Over the last century, manufacturers have used hydrogenated fats to produce specific functionalities. "When you take that away," says Mary Thomas, marketing manager, North America, Loders Croklaan, Glen Ellyn, IL, "you lose anything from shelf-life stability - which is probably the easiest to overcome - to solid-fat compositions that are used in specific applications like baking."  Shelf life can be extended through the addition of tocopherols and other antioxidants, Thomas says. "Or look for high-oleic oils. These solutions often come with costs and labeling implications," she warns.  High-oleic oils are also an option that can significantly reduce trans, and for some applications require no hydrogenation. For example, Cargill manufactures a trans-free solid shortening, a high-oleic liquid oil and high-stability liquid soybean oil, as well as other oils, that can take the place of hydrogenated fats in bakery and snack food applications.  The bakery and confection industries rely on the structure of fats to give their products body, texture and stability, says Wainwright. Fluidized shortenings may be able to replace plasticized shortenings in cakes, breads and muffins where the plasticity is not needed for structure. Functional ingredients (emulsifiers) are added and suspended by the crystalline matrix established by the introduction of a few percentage points of completely hydrogenated fat. Such systems are rich in unsaturates and contain little or no trans fats. Bakery icings and pastry are good candidates for the use of animal fats in their formulation. "Crackers are generally fairly lean formulations prior to the application of any surface sprays - that is where the fat comes in," Wainwright says. "Today most (spray oils) are high-stability oils that tend to be at least 20%, and often much higher, trans. Alternative options might include such things as coconut or high oleics."  When the switch was made away from the use of tropical oils in favor of hydrogenated fats, the confection industry continued to use tropical oils to maintain product quality. These minimally processed oils may again be the fat of choice for manufacturers of pastries and other bakery items, as they have less trans fat than their hydrogenated counterparts. "Many majors are reconsidering the use of tropical oils as an ingredient in some form. They may be a valuable tool, either by themselves or in combination with other fats. These offshore oils definitely have an application as surface spray oils," says Wainwright.  "We may end up going back to where we were," he says, as consumers are faced with choices of palm and palm kernel or coconut oils in their foods versus trans fatty acids. However, there will have to be a re-education of the consumer if processors are to go back to using tropical oils that have, for the past decade, been off limits to most shoppers.Fats on the cutting edge  Biotechnology can play an important role in manipulating the fatty-acid content in oilseeds. Traditional plant-breeding methods have produced plants with greater oil content, and oils that are high in oleic acids. Genetic modification can speed the process along, producing oils with a high oleic content that have oxidative stability and many other features important to processors. Genetic engineering introduces genes from selected plants into existing crops and allows the development of new crops to produce oils previously available only in limited quantities. Genetic engineering has also been used to control the length of fatty-acid chains, the amount of unsaturation and the triglyceride structure (by allowing specific placement of fatty acids on the molecule). Future possibilities include bioengineered oilseeds with reduced calorie content, bioavailability or specific functional characteristics.  High-oleic oils have good stability and can be used in place of many types of hydrogenated oils. Average soybeans contain around 20% oleic acid. High-oleic soybean oils can contain 60% to 85% oleic acids. High-oleic canola and sunflower oils are also available; many have been developed by traditional plant-breeding techniques, although some have used genetic modification.   Standard sunflower oil contains approximately 20% oleic, but AC HUMKO offers a series of high-oleic oils extracted from traditionally cross-bred sunflowers under the Trisun brand name. These range from 80% to about 90% oleic, which, along with decreased levels of the polyunsaturated linoleic acid, results in higher stability than regular sunflower oil, with OSI (oil stability index) values ranging from 10 to over 30 hours (35 to 80 hours AOM stability). Addition of tocopherols can lengthen shelf life, and light hydrogenation can increase the stability for frying applications, as well as lengthen shelf life.  Soybean oil developed with a low-linolenic fatty-acid profile requires less hydrogenation to achieve the desired manufacturing qualities, and thus contributes less trans fat to the diet. Soy oils high in stearate and palmitic acids can be used in margarines to reduce the need for hydrogenation, since these are more solid at room temperatures. Stearic acid has also been found to have little effect on elevating cholesterol levels, and is under study for a variety of food applications.   LoSatSoy, a vegetable oil manufactured by Optimum Quality Grains, LLC, West Des Moines, IA, is a reduced-saturated-fat soybean oil that has only 4% palmitic acid, compared to traditional soybean oil, which has 10% palmitic acid. Stearic acid content is 3% and 4%, respectively. This highly stable oil can be used in frying or salad dressing applications.  High-laurate canola oil has been developed as a tropical fat alternative. Laurical®, a genetically modified canola made by Calgene, Davis, CA, is a structured triglyceride that is cocoa-butter compatible. The genetic modification results in a triglyceride that essentially takes the form of C12/C14-C18-C12/C14 (lauric/myristic-stearic/oleic/linoleic-lauric/myristic) rather than the more random and virtually lauric-free structure of standard canola. Hydrogenation increases stability by shifting the makeup toward stearic and oleic. High-laurate canola can be used in confectionery manufacturing as a whole or partial substitute for cocoa butter. It is non-tempering, resistant to bloom, and has a good mouthfeel and a bland flavor. Optimum also offers high-oleic sunflower oils and low-linolenic oils. "High-oleic soybean oil has the same benefits biologically as olive oil - lots of monounsaturates," says Judi Eilertson, marketing manager, oil, for Optimum. "In frying operations, it doesn't produce off-odors or flavors as does high oleic canola oil. This is the healthiest fat you can have."  Plants developed through traditional crossbreeding techniques might have some advantages over genetically modified organisms (GMOs), especially to exporters. The European Union, in particular, is skeptical of the genetic modification process, and many nations have banned products containing genetically modified ingredients. "We ship a lot of this (high-oleic sunflower) product to Europe," says Shockley. "They want to avoid genetically modified crops, and about 30% of the soybeans grown are Round Up Ready® soybeans. Since that's genetically modified they don't want soybean oil from the U.S. Ditto for cottonseed, canola and corn." Transgenic crops such as Round Up Ready soybeans and Bollgard® cotton are commingled throughout storage and processing with non-GMO varieties.  The other question in Europe is the type of labeling that might be required for manufacturers who use GMOs, Thomas notes. "There are two proposals for Europe that have different implications. One will have products labeled as GMO-free and the other, in essence, says that the product doesn't come into contact with any GMO materials. The latter will be more stringent in interpretation than the former."   Furthermore, genetically altered crops that are destined for use as identity-preserved oils must be handled in a way that ensures their separation from other crops from harvest through processing, says Wainwright. This means dedicated silos and processing equipment in order to preserve the integrity of the crop and of the final ingredient.   Additionally, some U.S. activists are demanding labeling of genetically modified ingredients. So far the FDA has refused to consider such a proposal on the grounds that all plant breeding involves the genetic manipulation of plants, and they do not consider breeding techniques material information subject to labeling, according to Henry Miller, Ph.D., senior research fellow, Stanford University, Stanford, CT.Processing options  Oil-processing methods may be one of the best ways to reduce the amount of trans fats in processed foods. Oil scientists are looking at old and new ways to process oils that will deliver the qualities manufacturers need while providing the trans-free ingredients that consumers will soon demand.  Interesterification, which is also called rearrangement, uses catalysts to rearrange or redistribute fatty acids on the glycerol backbone. By altering the starting oils and modifying the process and catalysts, reductions in the trans content can be achieved. This process can improve the melting and crystallization properties of oils, making them suitable for the production of table spreads and shortenings. Interesterification of oils with high oleic oils would improve their shelf life. Interesterification has recently been used in the production of trans-free margarines.   "Interesterification is old technology," says Wainwright. Commercially practiced for nearly 50 years, it was originally used to improve the creaming properties of lard. In the 1950s, interesterification was proven valuable in the development of cocoa butter alternatives. "As vegetable-based shortenings replaced lard and the enthusiasm for hard butters grew, interesterification was directed almost exclusively toward hard butters in this country," he points out.  Depending on the process and the catalyst, the rearrangement achieved by interesterification might be random or directed. A directed rearrangement can allow further modification of shortening properties. Proper selection of fully hydrogenated fats enhances the development of beta-prime crystal structure. This raises the melting point of the finished product and gives it structure. "You can make a pretty good shortening with this process," says David Shockley, group leader, technology, AC HUMKO, Memphis, TN.  Interesterification is also being looked at for mixing vegetable and animal fats, such as lard. "People are becoming interested in using animal fats again in products," says Shockley, largely because of their stability, lack of trans and low cost. Interesterified lard was formerly called rearranged lard, and had better production qualities than plain lard, he says. Now, as a no-trans alternative, people are looking to lard, and even mutton tallow, again. The problem with interesterified technology, Shockley says, is because it is so old, many processors no longer have the proper equipment available.  Other modified animal fats may have a place in a trans reduction scheme. Appetize®, a cholesterol-free shortening made from cholesterol-removed meat fat and vegetable oil is being offered by Bunge Foods, Bradley, IL. The product provides "classic" meat-fat flavor to formulations for both the baking and frying industries. Because the ingredient blends solid meat fat with liquid vegetable oil, it contains no trans fatty acids. The product has a high heat stability and extended shelf life. In a human clinical study of Appetize cholesterol-free fat, conducted by the University of Minnesota, Minneapolis, subjects experienced a 9% drop in LDL cholesterol, and a 7% drop in overall levels of cholesterol when consuming the cholesterol-free ingredient over a four-week period.  Fractionation can be useful for both offshore and domestic oils. In fractionation, crystallization of triglycerides is done over carefully moderated temperature and time conditions; the solids are then removed at selected temperatures. This process produces a firm or plasticized component that can be used as a structuring fat. Fractionation can also be used to improve functionality by removing the higher melting components, thereby improving mouthfeel.  By changing the catalysts in the hydrogenation process, oil manufacturers can reduce the amount of trans in a shortening-type product. However, says Wainwright, this is an insignificant trade-off, as the alternative catalysts (copper and platinum) are too expensive to use and the amount of trans reduction is small. In addition, the level of saturates formed is generally significantly higher.  Electrochemical technology, pioneered by scientists at Tulane University, New Orleans, has not yet been proven commercially viable. This process depends on mild hydrogenation conditions to reduce the trans-isomer content of a hydrogenated oil by at least 50%. The rationale behind this method is that trans isomers are produced because of the rigorous conditions it takes to hydrogenate an oil by the current method. If processing conditions were less severe, the reaction (production of trans) would be less severe as well.  Researchers at the USDA's Agricultural Research Service are looking at supercritical and subcritical extractions for selective hydrogenation. Hydrogenation performed under supercritical carbon dioxide has a much faster reaction rate and allows for better control over the ratio of cis to trans isomers.Healthful options  Fats are in the news and on processors' minds not only for their functionality and labeling issues, but in some cases, for their health benefits as well. "Anything that falls under the category of nutraceuticals is a very big trend," says Thomas, "and I believe it's a long-term one. The idea of eating something to look better, to feel better, is more appealing than having to give something up."  Evidence is emerging that we may need to increase our intake of certain types of fat. Humans do not synthesize two of the fatty acids essential for health - linoleic acid (LA) and alpha-linolenic acid (ALA). Therefore, these essential fatty acids must be obtained from the diet. With LA, the body produces gamma-linolenic acid (GLA) and arachidonic acid (AA), known as the omega-6 polyunsaturated fatty acids (PUFAs). ALA produces eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), known as the omega-3 PUFAs. The omega numbers indicate the position of the first double bond occurring from the methyl end of the fatty acids.  Infant and fetus development depends on AA, GLA, EPA and DHA, which are present in mothers' milk. Very strong scientific evidence links omega-3s to lower plasma triglycerides. Excessive triglycerides are a risk factor for heart disease. Further studies indicate that omega-3 PUFAs help reduce, or work to treat, cardiovascular disease, inflammatory bowel disease, rheumatoid arthritis, menstrual discomfort, asthma, breast and colon cancer, and some skin conditions. A recent study by Applied Biometrics, Burnsville, MN, says that 82% of Americans are aware of fish oil as a potentially beneficial nutrient and 53% are especially aware of omega-3s.  Found primarily in cold-water fatty fish, these PUFAs have recently been developed for industrial use - deodorized and in convenient form. Menhaden fish oils are neutralized and bleached using diatomaceous earth. Peroxides, aldehydes and ketones are also removed, which are implicated in the development of off-flavors. Adding tocopherols or synthetic antioxidants extends the shelf life of these polyunsaturates, which would otherwise succumb to rapid oxidation. The oils can be microencapsulated for a dry powder form. These stabilized fish oils are finding their way into infant formulas, food supplements, and food-enrichment ingredients. The FDA has recently approved the addition of menhaden fish oils in a wide range of food products including margarine, salad dressing and many dairy products, to name a few of the options. Pasta and breads have also been formulated using fish-oil derivatives. Technologists at Omega Protein, Barrington, IL, have added refined menhaden fish oil to ice cream and summer sausage. "Anything that is refrigerated or frozen is a good delivery system from a stability standpoint," recommends Richard Schoenfeld, vice president, oil marketing, Omega Protein, Barrington, IL.  Linoleic acid is predominant in most vegetable oils, but some plants contain significant levels of alpha-linolenic acid. After consumption, about 15% of ALA is converted to EPA and about 5% is converted to DHA in humans. This conversion is affected by various dietary factors; consuming high levels of linoleic acid, for example, has been shown to reduce the rate by as much as 40%, and saturated and trans fatty acids may also have a negative effect. Soybean and canola oils contain some ALA, but flaxseed contains a level of about 57% of the total fatty acids. With about 16% omega-6 fatty acids, flax has an omega-6:omega-3 ratio of 0.3:1.1.  The typical Western diet is high in linoleic acid and low in omega-3 fatty acids, and some nutritionists recommend replacing omega-6 fatty acids with omega-3s. The British Nutrition Foundation, Health Canada and NATO recommend that 1% of dietary intake come from omega-3s. There is currently no official U.S. dietary guidelines for omega-3s, says Schoenfeld, although many nutritionists suggest that 3 grams of these fatty acids should be consumed daily. However, he notes, "there is an initiative in progress to develop a Daily Value" for omega-3s.  Many researchers also believe that substituting monounsaturated fatty acids for saturates also produces a significant decrease in the incidence of heart disease. This is one aspect popularized in the Mediterranean diet. There, much of the fat consumed is olive oil, whose predominant fatty acid is the monounsaturate, oleic acid. In the Mediterranean, monounsaturates typically provide over 15% of energy in the diet, and the primary source is olive oil. This is believed to be a factor in the low incidence of heart disease in the region, as compared to areas that consume the higher levels of saturates found in the typical Western diet. Nuts are also high in monounsaturates and, while nut oils are available, from a price perspective they fall into the gourmet food range.  Omega-6 PUFAs are found in borage seeds and evening primrose seeds. They are processed by extraction of the raw material, removal of the free fatty acids, elimination of contaminants, removal of taste and smell compounds, and stabilization into a refined oil. The fatty acid of interest is gamma-linoleic acid (GLA), which the body converts to an anti-inflammatory eicosanoid. It is believed to have several health benefits, including a positive effect on skin diseases such as eczema, and may protect against heart disease and cancer.  Conjugated linoleic acid might be another fatty acid that is poised to take the health or functional food spotlight. This isomer of linoleic acid is found in dairy foods and red meat.  Pharmaceutical uses for rice-bran oil have increased in recent years as well. An enzymatic extraction of the oil from the rice bran yields only 2% of the weight of the rice. However, its use as a supplement makes it of interest to the food processor. Tocopherols and tocotrienols in rice-bran oil have been found to be anticarcinogens and antioxidants. Several studies show that rice-bran oil appears to be effective in reducing cholesterol.  Structured lipids can be formed by combining glycerol and fatty acids into a triglyceride using esterification. Attaching medium-chain fatty acids onto a glycerin molecule forms medium-chain triglycerides (MCTs). The metabolic pathway of MCTs is quicker than that of typical fats and oils, resulting in a fat that has seven calories per gram, rather than the typical nine calories per gram. "Our MCTs, although fully saturated, are a pourable liquid at room temperature," says Shockley. They're primarily used in nutritional beverage and bar formulation and although the usage level is very low, the process is very expensive, he says, so application outside of the supplement market is limited.  There's a lot to consider when working with fats, and more innovation is sure to follow, as industry continues to juxtapose the health considerations of fats and oils with their functionalities in food products. The options for fats and oils manufacturers will only continue to expand, as food scientists and oil chemists build on their knowledge of these most critical ingredients.Back to top

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