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Fats and Oils

 
Fats and Oils

November 1997 -- Cover Story

By: Ronald C. Deis, Ph.D.
Contributing Editor

  Countless reports concerning the negative effects of fat and oil consumption have shifted today's dietary focus toward fat elimination. This is unfortunate, because as any student of nutrition knows, fats represent an essential dietary component.

  Fats act as important energy sources, especially during growth, or at times when food intake might be restricted. Protein and carbohydrates usually provide 4 kcal/gram; fats usually provide about 9 kcal/gram. Linoleic and linolenic acids are regarded as essential fatty acids that aid in: absorption of vital nutrients; regulation of smooth muscle contraction; regulation of blood pressure; and growth of healthy cells.

  On the negative side, the U.S. Surgeon General has stated that consumption of high levels of fat is associated with obesity, certain cancers, and possibly gall bladder disease. The Surgeon General also notes that strong evidence exists for a relationship between saturated-fat intake, high blood cholesterol, and coronary disease.

  Rather than viewing all fats as "bad," most nutritionists urge consumers to control the percentage of calories as fat in their diets, and to limit levels of saturated fat and polyunsaturates. Current government guidelines state that total fat intake should be no more than 30% of total calories. Saturated fat should make up less than 10% of calories, and monounsaturates should make up 10% to 15% of calories. This presents a dilemma to food technologists: How can they follow nutritional guidelines, yet design products that adhere to these recommendations? Besides furnishing high levels of calories, fat also can provide high levels of functionality based on its composition.

Why use fats?

  U.S. fat consumption occurs primarily through ingestion of salad and cooking oils, followed by frying fats and bakery shortenings, then meat, poultry, fish and dairy products (cheese, butter, margarine). Each of these applications has different qualifying factors for the fat used.

  In fried foods, oil acts as a heat-transfer medium, but also becomes a component of the food. Because of this dual function, the oil must meet a number of requirements. It must have good thermal and oxidative stability. It also must have good flavor, good shelf life and acceptable cost. It also should offer consumer appeal.

  Fats and oils provide important textural qualities to certain foods. Much of this is due to specific melting qualities and crystal structure, and some are provided by the "shortening" effect of fats, primarily in baked goods. Fats provide baked goods with a characteristic rise, flakiness, tenderness, strength, "shortness," and cell structure that cannot be duplicated in fat-free varieties.

  Fats and oils are integral to lubrication of foods in two ways: through use as release agents as a part of the cooking process; and as a lubricant during mastication, causing a cooling and coating sensation picked up as moistness in baked goods. Fats modify flavor release and affect mouthfeel by providing viscosity and coating effects. They also possess their own characteristic flavors (animal fats, olive oil and peanut oil are classic examples) and they also serve as an important flavor carrier in foods.

  The appearance of a food product also can be affected by fat. Liquid oils tend to produce a shiny appearance, while solid fats create an opaque look.

A matter of saturation

  All of the functional factors are impacted by the type of fats used. In turn, the type and composition have health consequences. Some of the issues surrounding health and functionality are better understood if we examine the nature of fat, as well as the composition of the predominant fats and oils available for food use. Fat molecules consist of three fatty acids linked to a glycerol backbone. Native fats and oils are made up of mixtures of a wide range of fatty acids arranged in varying ratios and positions on these triglycerides. This determines the characteristics of a particular fat, and creates a wide selection of properties.

  The terms important to health and stability relate to the degree of "saturation" or "unsaturation" of an oil. If a fatty acid is "saturated," it means that the maximum number of attachment sites (four) on the carbon atom are filled by another attached carbon or a hydrogen atom, and only single bonds exist. Unsaturated fatty acids contain one or more double bonds between carbon atoms in the chain. If an unsaturated fatty acid contains one double bond, it is referred to as monounsaturated (oleic, 18:1). If more than one double bond exists, the fatty acid is polyunsaturated (linoleic, 18:2; linolenic, 18:3). If an oil contains a predominance of saturated fatty acids, such as palm oil or coconut oil, it is commonly referred to as a saturated fat. Conversely, if the fat is predominantly unsaturated, it is referred to as an unsaturated fat.

  The degree of unsaturation has a number of major effects:

  • Melting point: a number of factors, including degree of saturation and molecular weight, determine the melt point of a fatty acid and, ultimately, a fat. A number of melt points, in relation to degree of unsaturation and number of carbon atoms, are noted in the table titled "Saturation Influence on Melt Point."

  • Most, if not all, saturated fats have the effect of elevating blood serum cholesterol, a known health-risk factor.

  • In terms of stability, unsaturated fatty acids are more susceptible to chemical reactions, most notably oxidation, leading to rancidity.
  An oil's stability often is described in terms of iodine value (IV) or the active oxygen method (AOM). The iodine value measures the degree of unsaturation -- the iodine readily reacts at the double bond. IV is reported as the number of grams of fat under standard conditions. The higher the IV, the higher the level of unsaturation and the more unstable the oil. The relative number of monounsaturates to polyunsaturates also affects the IV.

  AOM expresses the number of hours of stability when air is bubbled through a fat sample maintained at 200(F. A frying oil needs at least 60 hours AOM, and many plastic shortenings have an AOM of 100+.

Understanding the native oils

  Categorizing fats based on their structure helps us better understand the issues presented by some of the commonly used oils. Bailey's Industrial Oil and Fat Products divides fat into 10 categories, including six vegetable-oil categories: lauric, vegetable butter, oleic-linoleic, erucic, linolenic, and conjugated acid.
  • Soybean oil is part of the linolenic group, characterized by a high linolenic level (8%), in addition to oleic and linoleic. Because it is high in polyunsaturates (61%), soybean oil is usually partially hydrogenated to prevent oxidation, which causes "fishy" and "grassy" off-notes. Because soybean oil is low in saturates (15%), it is liquid at room and refrigerated temperatures. It is commonly used in frying, salad dressings, margarine and baked goods.
  • Canola oil, a genetic modification of rapeseed with a reduced erucic acid content, belongs to the oleic-linoleic group. Canola contains the lowest level of saturated fat (6%) as well as a high level of monounsaturated fats (58%). Canola can be hydrogenated to increase stability. It is liquid at room temperature and refrigerator temperatures. Canola is used in shortenings, frying, salad dressings and margarine.

  • Cottonseed oil is commonly used in salad and cooking oils, snack foods, mayonnaise, frying and baked goods. Cottonseed contains virtually no linolenic acid, so it is generally regarded as a relatively stable frying oil. It has a characteristic buttery flavor, and often is blended with other oils for stability. (Cottonseed contains approximately 27% saturated fatty acids.) Cottonseed oil is liquid at room temperature and partially solidifies below 10° to 16°C. It is often found as a hardening agent in plastic shortenings.

  • Peanut oil, also part of the oleic-linoleic group, contains low levels of linolenic and very low levels of linoleic acid. It contains about 18% saturates, but 48% monounsaturates, providing a relatively stable, although expensive frying oil. It is liquid at room temperature, but gel-like at 2° to 4°C. Peanut oil has been used in frying, salad and cooking oils, margarine, snacks and baked goods.

  • Sunflower oil contains high levels of linoleic acid (78%), with relatively high linolenic-acid levels. Sunflower oil is high in vitamin E, another health benefit. Total saturated fats are 11%, with 20% monounsaturated and 69% polyunsaturated.

  • Corn oil also is a member of the oleic-linoleic group. Corn oil is low in saturates (13%) and relatively high in polyunsaturates (62%). Corn oil has been used in snack foods, salad oils, margarine and baked goods.

  • Palm oil contains about 50% saturated fatty acids, and is semi-solid at room temperatures. Crude palm oil also provides a rich source of carotenoids -- particularly high in retinol equivalents.

  • Coconut oil, with 92% saturated fatty acids, has the highest saturated fatty acid level of any vegetable oil. It is firmly solid at 21°C, but is liquid at 27°C. Coconut oil is commonly used as a spray oil on cookies and crackers, in whipped toppings, and in icings and glazes.
  "The source oils are still relatively important to the consumer," says Bob Wainwright, manager, technical services, C&T Quincy, Charlotte, NC. "Canola has a positive aura. Sunflower oil still tends to fall in that category and certainly olive oil has a positive image due to all the positive press it's received in recent years."

  Part of what makes these popular are relatively low levels of saturates. Since fats and oils are triglycerides, there really are no "saturated fats" or "unsaturated fats." One fat may be predominant in saturated fatty acids, but it also will typically contain monounsaturated or polyunsaturated fatty acids. Different ratios of saturated and monounsaturated or polyunsaturated fats lead to different benefits in terms of functionality, stability or health.

  Levels of oleic, linoleic and linolenic acids are relatively important. As noted previously, oleic acid (18:1) is a monounsaturated fatty acid. Linoleic (18:2) and linolenic acid (18:3) are polyunsaturated. Since linolenic acid has fewer saturated sites, it is more prone to oxidation. From a functional standpoint, its level should be minimized to enhance stability; from a health standpoint, polyunsaturates are recommended at less than 10% of calories.

  While saturates are still considered to be "unhealthy" by most consumers, there is evidence that not all saturates have a negative impact on health. Stearic acid, for example, is considered to be neutral in its effect on blood cholesterol levels.

  "All the science isn't in, but there are some strong indicators that stearate, for example, is probably not a problem, at least not to the extent of things like palmatate and myristate," points out Wainwright. "There's also the fact that the long-chain saturates, especially the C22s are poorly absorbed and therefore have less caloric density."

Fixing the problem

  When source oils high in saturates became a major health issue in the 1980s, vegetable oils -- with the aid of hydrogenation -- were able to fill the gap. In hydrogenation, hydrogen is added to saturate the double bonds occurring in the fatty acids. This process hardens oils into fats, and also increases the oxidative stability of oils. Hydrogenation, developed in the early 1900s, became the standard method to stabilize soybean oil during the 1950s. Soybean oil has always been a commercially important oil, but maintains one serious deficiency -- relatively high linolenic-acid content. Linolenic is very easily oxidized, causing a green, rancid flavor to develop.

  The simplest and least expensive solution to increase oil stability is to hydrogenate. But as it turns out, hydrogenation generates another potential red flag in terms of health -- trans fatty acids -- so biological methods (transgenic methods, cross-breeding) and processes, such as interesterification, that increase stability are being developed. Still, what often happens is that in order to increase stability and provide functionality, a native oil with a relatively low level of saturates is transformed into a product with increased levels of fatty acids that may promote health problems.

  "Time and time again, people, even technical people, are surprised that what it amounts to is essentially a trade-off," Wainwright says. "Basically, there are two ways to get the body and the structure that you need -- that's either by hydrogenation, and you get trans fatty acids or you have to increase the saturated fat content. Without either of those, you have soup -- something without any structure. So, if you want to build body just with things that are purely triglyceride in nature, you're really at the end of the road. Unless you move into a structured lipid kind of system where you begin to take advantage of the body provided by things like the short-chains, coupled with the long-chain fatty acids."

  In regard to biotechnology, Wainwright notes that "basically what's happening is that we're encouraging Mother Nature to do the structuring for us. But again, what we see are elevated levels of palmitate or stearate, relative to the traditional varieties. The bottom line is that we're still elevating the saturates, whether we're manipulating the genetic factory in the cell or bringing the fats into a hydrogenater or oil-processing facility. It does allow you to get away from the trans problem however."

  Interesterification, a catalytic (chemical or enzymatic) method of redistributing the fatty acids on the glycerol portion, is another method that can increase functionality without negatively affecting healthfulness. This process can create a random distribution, or it may be directed to a degree that actually modifies the shortening properties, without increasing saturation or creating trans isomers.

  "The randomization of the fatty acids makes the molecules more alike," notes Willie Loh, market development, vegetable oils, Cargill Foods, Minneapolis. "There are multiple-step processes where you can take off specific fatty acids and then put them back on. But that's very, very expensive." Because of the high cost of the process, the products are primarily targeted toward high-value applications, such as confectionery fats.

  "You primarily see things like palm kernel, coconut or palm," Wainwright says. "(Manufacturers) are primarily subjecting them to random interesterification to get cocoa-butter substitutes. In Europe, they are starting to utilize it because there is clearly a big push to get trans reduced, especially in margarine. But the advantage there is that palm and palm kernel don't have the negative connotation. Also, in the last three or four years, they have directed interesterification up-and-running commercially. Unilever commissioned a plant, based on enzymatic interesterification, in the Netherlands to make cocoa butter alternatives by combining palm for the palmitate and stearate with high-oleic sunflower oil for the oleate, and forming s-o-s- or s-u-s-type triglycerides."

The configuration controversy

  Hydrogenation is one method of increasing oil stability and changing functional properties, such as melt characteristics. However, during the process, variable amounts of the unsaturated fatty acids that are not hydrogenated are converted from the cis to the trans configuration.

  In a trans double bond, the two hydrogen atoms adjoining the double bond are located on opposite sides of the carbon chain. As opposed to the cis conformation -- in which the hydrogen atoms are on the same side of the carbon chain -- the double bond's angle is smaller. This results in a more linear, rigid molecule with a higher melting point. To illustrate, consider oleic acid (18:1, cis) vs. elaidic acid (18:1, trans). The melting point of oleic acid is 13°C, while the melting point of elaidic acid is 44°C. Typical hydrogenated fats that are solid at room temperature may contain up to 15% to 25% trans fatty acids, while the level in partially hydrogenated fats is lower depending upon degree of hydrogenation.

  The trans forms occur naturally in the body fat of cattle and sheep, with concentrations from 4% to 11%, as well as in milk and butter. In 1996, the American Society for Clinical Nutrition (ASCN)/American Institute of Nutrition (AIN) Task Force on Trans Fatty Acids stated that "the estimated per capita consumption of dietary trans fatty acids from vegetable and animal sources is 8.1 to 12.8 grams/day," which is 2% to 4% of energy intake. Hydrogenated vegetable oil makes up 80% to 90% of total trans fatty acids in the diet. Consumption of trans fatty acids escalated in the mid-1980s, when major fast-food chains switched from beef tallow to heavily hydrogenated vegetable oils containing high levels of trans fatty acids. Despite this peak in the previous decade, the average overall consumption of trans fatty acids has remained fairly stable during the last 25 years: As their level in margarines and shortenings has decreased, the level of trans fatty acids in fried foods has increased.

  Trans fatty acids have remained a controversial subject for many years, a situation that has continued because of conflicting data regarding their effect on blood serum cholesterol. In 1995, an International Life Sciences Institute (ILSI) expert panel reviewed studies on trans fats, and concluded that evidence did not support a clear link between this isomer and coronary heart disease. They noted that a hydrogenated vegetable oil would raise plasma cholesterol concentrations when substituted for native oil. The panel recommended additional research to clear controversies surrounding trans fatty acids and their effect on plasma lipoproteins.

  The level of activity in this research area can be expected to escalate in response to major changes expected in the fats and oils industry. One of the changes relates to expected new regulation for food labels.

  On Feb. 14, 1994, the Center for Science in the Public Interest (CSPI) petitioned the U.S. Food and Drug Administration (FDA) to require that trans fat be combined and labeled along with saturated fat. They acknowledged that FDA, within the Nutrional Labeling and Education Act, had placed a 0.5 gram limit on the amount of trans fat allowed in foods claiming to be "saturated fat free." CSPI has suggested that "saturated fat free" foods should contain less than 0.5 gram total of saturated and trans fatty acids combined, per reference amount and per labeled serving. "Low in saturated fat" and "contains a small amount of saturated fat" would be designated for foods with 1 gram or less total saturated plus trans fatty acids per reference amount, and not more than 15% of calories from saturated plus trans fatty acids. "Reduced saturated fat" or "less saturated fat" would be reserved for foods containing at least 25% less saturated plus trans fatty acids.

  FDA has not responded to the CSPI petition, since the agency is awaiting the results of an Agricultural Research Service (ARS) clinical study. This study, funded by ILSI, examined several dietary fatty acids, including trans, and their effects on cardiovascular disease. The study, led by ARS researcher Joseph Judd, was completed last year and is now undergoing peer review. This report is expected to be issued early next year. Clinical data to date have been inconclusive, but many organizations have acknowledged that trans fatty acids raise plasma cholesterol to some degree above native oils.

  The ASCN/AIN Special Task Force report recommended that diets should be controlled to less than 30% total fat and less than10% total energy as saturated fat. Meeting these goals would have the effect of decreasing trans fatty acid intake.

  Whatever the FDA decision may be, the food industry should consider options for control of these isomers, especially considering the prevalent attitude toward them in Europe. "In Europe, it's a big issue," says Loh. "We often are asked if a product contains trans, and if it does, they're not interested. They have taken a much stronger position than the North Americans. I think the Europeans are much less concerned about the cardiovascular issues; they're concerned about the nutrition as well as cancer. Across the ocean, there's a different perception about the importance of the issues."

  Naturally saturated oils, such as cottonseed, may find more use. Or, manufacturers may blend saturated (no trans fatty acids) fats or hard butter fractions with highly unsaturated oils to provide low or trans-free blends with the required functionality. "The advantage to blending with a hard fat is, in some cases, that if you use a very hard fat, where you hydrogenate down to very low IVs, the trans is effectively gone," Loh says. "But that's where you need a high-stability oil. If you use a standard soybean salad oil with a hard stock, you get solids but no stability, so you may be worse off. If you want stability without hydrogenation today, that means you need to start out with one of the high-oleic oils."

  Another alternative may be to consider high-saturated transgenic oils, using stearic acid, generally regarded as a "neutral" saturated fatty acid.

Biotech bonuses

  Genetic engineering, whether standard cross-breeding or transgenic techniques, has been used to modify oil properties and composition. Much of the work in the "property-enhanced oil" area has been directed at frying applications, since this is a high-volume application.

  For a number of years, sunflower oil has been a high-interest oil -- it is naturally low in linolenic acid, and it received early attention with the development of a high-oleic version. Its main drawback has been price, but it is still available through several sources.

  Other vegetable oils also are being improved through these techniques. In November 1996, ARS announced two new soybean varieties. "These two varieties, N94-2575 and C1945, each have a total saturated fat content of about 7%," says geneticist Joseph W. Burton, ARS, Raleigh, NC. Burton and James Wilcox, ARS, West Lafayette, IN, reduced the palmitic acid content, replacing it with oleic acid. Seeds for growers should be ready in about three years, according to Burton.

  Meanwhile, E.I. DuPont de Nemours & Co., Wilmington, DE, has developed a genetically modified 80%-to-85% oleic acid soybean variety. Levels of linoleic and linolenic are 2% and 3%, respectively. The AOM induction time (the higher the number, the greater the stability) for the high oleic version exceeds 140 hours, compared to 15 hours for normal soybean oil. DuPont is working toward commercialization of this product, and continues research on other genetic varieties, including a low saturated fatty acid soybean (3.5% to 4.0% saturates), and high-methionine and high lysine varieties.

  In mid-September, DuPont and Pioneer Hi-Bred International, Des Moines, IA, announced the completion of an agreement for DuPont to invest $1.7 billion in Pioneer as part of a research alliance and a separate joint venture company to discover, develop and market new crops. These two companies plan to collectively invest $400 million in agricultural research next year, particularly in the genetic modification of corn, soybeans and other oilseeds to improve oil, protein and carbohydrate composition. The name of the joint venture company is Optimum Quality Grains, and it is expected to start up by the end of this year. Products will include high-oil corn and high-oleic acid soybeans, as well as the low linolenic soybeans, high-oil corn, and high-oil sunflowers.

  Laurical®, a high-laurate canola oil (approximately 40% lauric acid, C12), in 1995, received FDA approval for food and nonfood uses in the United States and Canada. This transgenic canola oil is "designed to function as a cocoa butter replacer in confectionery coatings and as the principal fat used in simulated dairy systems," according to Tony DelVecchio, vice president, commercialization, Calgene, Inc., Davis, CA. DelVecchio notes that the totally structured nature of the oil leads to unique properties. Since it becomes more efficient than a random fat, less can be used in a compound coating, while still obtaining the same texture and smoothness. The laurate ester is positioned only at the 1- and 3- positions only, with a C18 at the 2- position. Calgene continues to work on higher-laurate canolas (54%, 70%), as well as high stearate canola (in field trials) and canola oils high in medium-chain fatty acids.

  Several years ago, Cargill Foods, Minneapolis, MN, began a program toward developing more functional, healthy oils. As a part of this effort, the company developed Clear Valley(r) high-oleic canola oils and Odyssey™ 200 high stability oil. Cargill also will be launching a high-oleic sunflower oil this fall.

  Odyssey 200 is a partially hydrogenated high-oleic canola with 200 hours AOM for one to two years shelf life. A lighter hydrogenation produces less trans fatty acids and a neutral taste and a light, clear color. The low saturated-fat levels provide consumer-friendly label statements.

  "The Odyssey oils are not really positioned as healthy or non-healthy," points out Loh. "The reason is that the high stability oil category has such dramatic and extreme requirements. They are healthier. But most people use high-stability oils with the understanding that they do have trans due to hydrogenation, so that's not really an issue for them."

  "The natural foods people are faced with a conundrum," says Loh. "They want to have minimal processing, so certainly hydrogenation is not acceptable. Some also consider natural to mean co-pressed or expeller-pressed oil. What they face with these requirements is the lack of shelf-stability." This is one market for high-stability oils made without hydrogenation. For example, Clear Valley 65 (65% oleic, 10% linoleic, 5% linolenic) was developed for long-shelf-life spray-coatings, such as those used on granola bars.

  Corn oil has always represented a problem in terms of the amount of oil expressed -- only approximately 4% of the kernel weight. Several companies are in the process of developing higher oil varieties -- from 6% up to 20% oil. Both DuPont and Mycogen are working on high-oleic (approximately 65% to 70%), high-oil varieties.

  AC HUMKO Corporation, Memphis, TN, with Pioneer Hi-Bred International, has developed and commercialized a low-linolenic (23% oleic, 3% linolenic) soybean and a high-oleic/low-linolenic canola oil through cross-breeding techniques.

  Most work to date has focused on increased oil stability. However, "one of the areas that bio-modification holds promise in is structuring fats," says Wainwright. "Clearly, there are a lot of advantages to site specificity, whether it's for functionality in the case of chocolate-type fats or for metabolic considerations."

Lighten up

  Another issue was raised by a December 1994 petition to FDA from Nabisco Foods, Hanover, NJ. The developer of salatrim (which is sold by Cultor Food Science, Ardsley, NY, as Benefat(r)), requested that FDA allow declarations of fat on the nutritional label to reflect the amount of digestible fat in a product. Nabisco claimed that 5/9 of the fat is available in salatrim, so a "food factor" of 5/9 should be applied. FDA has proposed the use of a "digestibility coefficient" to refer to the portion of a fat substitute that is absorbed.

  Salatrim's structure is based on short-chain fatty acids (acetic, propionic, butyric), together with stearic acid, on a glycerol backbone. Industry groups have strongly urged FDA to consider exclusion of short-chain fatty acids from the definition of total fat. Short-chain organic acids do not contribute the same caloric energy, and do not behave chemically or physiologically like fats. Industry groups, such as the Grocery Manufacturers of America and Calorie Control Council, make the argument that: short-chain organic acids are completely miscible in water; are more readily digested and absorbed than fatty acids; are not associated with chronic diseases; and are not completely detected by AOAC methods for determination of total fat.

  Several products containing salatrim have appeared on the market, including Hershey's Great Escapes, Snackwell's Fudge-Dipped Granola Bars, and Hershey's Reduced Fat Baking Chips. Snackwell's, as an example, advertises "only 1.5g available fat per bar" on the front of the package. On the Nutrition Facts panel, total fat is listed as 3 grams, but a double asterisk directs attention to a statement below the panel, stating "contains 2.5g of salatrim per serving, only 55% of which is used by the body. Therefore, this product contains 1.5g (3% DV) of available total fat of which 1.5g (3% DV) is available as saturated fat."

  When these labels were introduced, FDA decided not to sanction the companies involved. Since the use of food factors is a new area, the government agency decided to consider its next steps before issuing a rule. On Dec. 20, 1996, FDA proposed a rule to amend nutrition labeling to provide for claims regarding reduced availability of fat. The comment period ended April 21, 1997. FDA received comments supporting both sides of the issue, and has yet to issue the rule.

Fishing for health

  One group of fatty acids becoming more prevalent in the media is omega-3 polyunsaturated fatty acids, also called omega-3 PUFAs. Many vegetable oils, such as corn, sunflower and safflower, are rich in omega-6 PUFAs. In these, the first double bond is between the sixth and seventh carbon atoms. In omega-3, the first double bond is between the third and fourth carbons. Some vegetable oils, such as canola and soybean, contain an omega-3 PUFA called alpha-linolenic acid. This PUFA is an omega-3, but is very different from omega-3 PUFAs in marine oils. Alpha-linolenic is 18 carbons long, with three double bonds.

  "The theory is, what you need is an ideal ratio between the omega-3s and the omega-6s -- somewhere between 1:3 and 1:5," explains Loh. "Sunflower has no omega-3, so they're out of the picture. A regular salad oil, both soybean and canola are pretty good in this regard."

  The omega-3 PUFAs in marine oils are longer, with more double bonds. The most prominent omega-3 PUFAs in marine oils are eicosapentaenoic acid (EPA), which is 20 carbons long, with five double bonds (20:5). Docosahexaenoic acid (DHA) is 20:6. Good sources of EPA and DHA are mackerel, herring and salmon.

  In the 1970s and 1980s, omega-3 PUFAs were widely promoted for their health benefits, due to some observations that populations with a high level of seafood in their diets had lower rates of cardiovascular disease. This spawned a bevy of other claims -- most not scientifically proven. Cardiovascular disease prevention has maintained a high level of interest, while other studies have looked into the effect of these fatty acids on arthritis, inflammation, brain development, vision, cancer, skin disorders and diabetes. The omega-6 PUFAs (linoleic, arachidonic, gamma-linoleic) are essential components of phospholipids in cell membranes. They are precursors for the synthesis of prostaglandins and other eicosanoids, which could contribute negatively to cardiovascular disease, allergic disorders and inflammation. The omega-3 PUFAs, especially EPA, also are precursors of eicosanoids, and actually compete with omega-6 PUFAs for critical enzymes. The omega-3s, however, have been identified as reducing risk factors for cardiovascular disease, and inflammatory and immune disorders.

  A large body of evidence points to an association between omega-3 PUFAs -- the long-chain variety, now referred to as LCPUFAs -- and reduction of cardiovascular disease. As a result, some governmental bodies have established recommended intakes. The British Nutrition Foundation recommended in 1992 that individuals consume 1.25 grams of LCPUFA daily. Estimates for the United States for current, per capita consumption point to less than 200 mg; this means Americans should consume at least slightly more than one additional gram per day. The Japanese food industry currently DHA-fortifies many products, including milk, cheese, yogurt, soft drinks, and confectionery and baked goods. High-LCPUFA eggs, developed through high-LCPUFA hen feed, also exist.

  On June 5, FDA announced that menhaden fish oil is GRAS for use in foods. Several forms of this now are available, including a microencapsulated form, which is suitable for use in baked goods, cereal, pasta, nutritional bars, beverages and soups.

  Earlier this year, FDA contracted the Life Sciences Research Office (LSRO) of the Federation of American Sciences for Experimental Biology (FASEB) to consider whether FDA should mandate the inclusion of DHA and arachidonic acid in premature infant formula. LSRO/FASEB held a general meeting in March to gather consensus, and its report is expected to be issued this year. Animal and human studies have indicated that LCPUFAs may be essential for visual functional development of the retina and visual cortex in early infant development. Currently, U.S. infant formula contains linoleic and linolenic acids (precursors of LCPUFAs), but not DHA.

  Research has suggested that infants are able to form the LCPUFAs from precursors, but not in sufficient quantity. Also, it has been noted that babies born prematurely do not receive adequate DHA and arachidonic acid because most of it is accumulated during the third trimester. Mothers of premature infants often are not able to provide breast milk. WHO/FAO and the British Nutrition Foundation have issued recommendations that infant formula contain DHA and arachidonic acid levels equivalent to the levels in human breast milk. This subject is somewhat controversial, since formula manufacturers maintain that adequate studies have not been completed to fully support addition to infant formula. Some studies have indicated that LCPUFAs may even retard growth in preterm infants.

One certainty: change

  Based on the amount of news and regulatory activity surrounding fats and oils, one thing is certain: change. During the coming year, new regulations regarding trans fatty acids, food factors and LCPUFAs are probable. These changes will influence activity within the arena of property-enhanced oils. If 1997 was any indication, mergers and acquisitions will continue to change the companies involved in oil sources and fortification of PUFAs. Ingredient cost will continue to be a factor. This definitely inhibited the success of sunflower oil, and could inhibit development of other oils if the benefit supplied by the ingredient does not justify the cost.

  "One of the trends in the food industry is that U.S. food companies are going global," says Loh. "Therefore, there will be a greater emphasis on oil stability. As global markets open up for American food companies -- who are at the same time striving to be low-cost producers -- many products are going to be produced locally for global distribution. This places a premium on stability."

  Several questions remain. Will trans fats become a major consumer issue? How will this affect the fats on the market and the required tests? Will we see new, lower-calorie fats on the market? Will the use of DHA and arachidonic acid be mandated in preterm infant and/or full-term infant formulas? What role will biotechnology play in providing healthier, more functional fats and oils? Stay tuned -- change is certain to occur.


© 1997 by Weeks Publishing Company

Weeks Publishing Co.

3400 Dundee Rd. Suite #100
Northbrook, IL 60062
Phone: 847-559-0385
Fax: 847-559-0389
E-mail: [email protected]
Website: www.foodproductdesign.com



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