Fats and Oils: Oil’s Well
Fats and oils have taken a bad rap over the years. But, a diet without fat would be dull, and many favorite foods and flavors would be lost if fat was completely eliminated.
CREDIT: The Canola Council/www.canolainfo.org
In addition to their function in high-temperature processing and in providing texture and mouthfeel; shortness in baking; and body in emulsifications and other formulations, oils and fats are powerful carriers of flavor. However, oils and fats have been maligned for decades with accusations that they are primary causes of obesity and cardiovascular disease.
Nutrition science evidence has been transitioning consumers to a better understanding of fat in the diet and its role in disease. In the late 80s and 90s, recognition of healthy oils—especially omega-3 fatty acids—began to introduce more balanced reportage on fats and effectively introduced the concept of “healthy fats” into the consumer consciousness, inclusive of the differences between saturated fats, unsaturated fats (including mono- and polyunsaturated fatty acids) and, of course, trans fats.
The pendulum is swinging. Most consumers now are aware that fat and oil might just not be as bad as they thought. Fat reduction and replacement by low-energy-density carbohydrate ingredients tends to not provide a net reduction in caloric intake. As a provider of satiety and a sense of fullness when it enters the intestinal tract, fat can reduce overall daily caloric consumption.
The past year has seen a welcome upsurge in clarifying the science behind oils, fats and lipid metabolism. Research supporting a less concrete connection between dietary fat—and even saturated fats—and a negative health outcome has led to fat being presented more realistically. Evidence increasingly suggests saturated fats are not the bulk of the problem in cardiovascular disease; rather, substituting sugar and carbohydrates in fat reduction could actually be the culprit.
Saturated fats inherently are stable and less prone to oxidation within the body. It is plausible that cellular oxidation and the associated inflammation actually is more problematic in elevated disease risk.
A better understanding of the complexity of fat in the diet has been a significant boon to manufacturers who make strategic use of oils and fats in food and beverages. Food ingredient suppliers are quickly taking best approaches for delivery of innovative and healthy new products, and consumers are reaping the benefits.
Trans Fats in Transition
When artificial trans fat was added as a mandatory item on nutrition facts panels in 2006, food manufacturers took the initiative to reduce trans fat through ingredient substitution, with most artificial trans fats occurring in deep-fried foods, laminate and short dough products, and margarines. The momentum for trans fat reduction was initially swift, but according to Centers for Disease Control research, this reduction plateaued in recent years.
That’s about to change. In November last year, the FDA declared trans fats to be non-GRAS. Many processors are more than displeased with this action and anticipate increased difficulty and expenses involved in removing all vestiges of trans fat from products. Oil technologists already have developed an arsenal of technologies that effectively replace hydrogenation. They’ve created wide portfolios of fats and oils with the appropriate melting range for development of laminated and short doughs, and stabilized frying fats. So, while questions might be raised as to how strong the scientific basis for such an action was, food makers should know there’s no need to panic. Fat and oil ingredient developers have solutions in hand for future formulation needs.
Omegas by the Numbers
There is a range of different fatty acids, but in the diet, these predominantly are comprised of omega-6s, followed by omega-3s. Omega-3 fatty acids consistently show benefits for a wide range of healthful conditions, including cholesterol balance, fetal and child neural development, liver health, cognitive support and anti-inflammatory effects—as well as a score of other positive health advantages studied.
For formulators, however, there has not been consensus on what a recommended intake of these fatty acids should be. Suggested daily intake recommendations generally run between 500-2,000 mg.
There are many different omega configurations, even within omega-3 structures. The predominant omega-3s in the American diet are alpha-linolenic acid (ALA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).
ALA is predominantly found in plant sources, such as flax, chia, soybean, canola and walnuts. But, its conversion to the long-chain omega-3 fatty acids, such as EPA and DHA, is limited to about 10% (although some research has suggested it is higher than previously believed). Thus, while not technically essential, there is a strong need for EPA and DHA in the diet.
Conversely, while omega-6 fatty acids—especially 18:2 linoleic acid—are indeed essential in the diet, omega-6 fatty acids are not lacking in the North American diet. In fact, high amounts can interfere with the beneficial effects of omega-3 fats. This is why omega-3 fatty acid fortification has been a leading trend in improving nutritional quality of food for a generation. No omega-9 fatty acids are essential to the diet (other than in highly restrictive vegan diets).
Ratios of omega-6 to omega-3 in the North American diet typically are in the 15:1 range. However, the recommended ratio is closer to 4:1. Consumers consistently seek strategies for improving their health through nutrition interventions and show a preference for foods and beverages over pills.
Omega fatty acid content (including omegas-6 and -9) often is promoted on labels. But, when deciding to formulate a product, it is important to differentiate between marketing strategy and evidence-based science.
One potential challenge is that the comparatively large doses of omega-3 fatty acids necessary for health impact mean strong potential for noticeable sensory defects in the fortified product, and according to the type of omega-3 used. As product developers take advantage of the opportunities for adding omega-3 fatty acids to foods for promoting health through their products, the challenge of increased oxidative rancidity and fishy aromas arises.
These issues, of course, lead to negative taste and organoleptic impact and curtail the use of omega-3 as fortification in foods and beverages. Microencapsulated omega-3 fats were developed to counteract this negative impact, by using either gelatin-based beadlets, or beadlets composed of a saturated fat or carbohydrate base, depending on the application.
Traditionally, omega-3-rich fish oil was derived as a byproduct of fish processing, especially from salmon. But, given the explosive growth in global demand for omega-3 supplementation and fortification, fisheries are now dedicated to the production of omega-3, focusing on small pelagic fish, such as anchovies, herring and sardines. Krill has been utilized for omega-3 oil production and has a unique, high phospholipid and carotenoid content which has additional nutritional benefit.
Given that marine-sourced products are harvested predominantly from the ocean, a variety of concerns have been raised about the sustainability of these stocks due to the current and critical stresses on nearly all aquatic life, worldwide. Emphasis on algae- and vegetable-based omega-3 oils has therefore increased considerably, and a number of algae-based DHA/EPA products have been launched into the market in recent years.
One manufacturer recently opened a major facility in the south Texas desert, taking advantage of algae’s tendency to thrive in otherwise undesirable locations noted for hot weather and brackish water. Add the fact that algal oil production relies predominantly on solar energy, and the sustainability of algae-derived DHA/EPA ranks as superior.
When considering use of omega-3 fortification in foods, the microencapsulation material used and its stability under processing methods are critical to the stability of the product. Certain encapsulation materials are more stable in conjunction with acid (fat), while others are more stable to heat (e.g., carbohydrate). The latter is especially important with omegas, as they are particularly unsuited to high-heat applications. All of these oils have emulsification considerations if targeting use in beverages or other liquid applications.
Also, products encapsulated with gelatin might not necessarily meet kosher or halal standards unless certified. Currently, only algal omega-3 fortificants can deliver vegetarian sourced DHA and EPA. Interesting developments coming up include modified canola sources that produce their own high levels of omega-3s, as DHA and EPA, for a completely vegetarian-derived DHA/EPA.
A Hex on Hexane
The common use of solvents, such as hexane in vegetable oil extraction, has posed a challenge for food makers seeking clean label options to serve the rapidly growing consumer demand for chemical-free products. This also extends to the side products of oilseed extraction, such as defatted flours and proteins. Manufacturers of mainstream oils, such as soy and canola, have been able to make that accommodation through acquisition of large, high-shear extrusion and mechanical extraction systems.
A convergence of technology and economy is allowing smaller producers into the game. Small, yet highly efficient and completely state-of-the-art systems for refined expeller-pressed vegetable oils are now available for those niche oil producers, and the timing could not be better: While the prices of hexane and other chemical solvents are rising, the cost of producing expeller-pressed oils is declining.
The oilseed processing industry uses hexane to process over 90% of all soybeans processed in North America. In North America, expeller-pressed soybeans, canola, cottonseed, sunflower and camelina (false flax) are growing rapidly within the human food and animal feed industries. Consumers concerned about health, safety and the environment are naturally attracted to meat, milk and egg products produced by animals that were fed diets naturally processed without chemicals.
Refined, expeller-pressed vegetable oils command premiums within the foodservice, specialty health food stores and the oils’ sections of most grocery stores. To refine expeller-pressed oils without caustic chemicals (known as “physically refining“) is another positive action that continues to attract more users of these vegetable oils.
Another practical reason small-medium oilseed processors like mechanical processing is the much larger capital costs to build an oilseed plant using hexane. Increased capital costs for a hexane oilseed extraction plant can exceed four times the costs of mechanical processing.
This is adapted from a column by Duncan Nesbitt, published by Insta-Pro Inc. November 2013. Reprinted by permission.
With reduction of trans fat now an even more critical goal for processors and foodservice, (see “Trans Fats in Transition,” page 80), oil and shortening developers have employed two main strategies for deep-frying, baking and other high-heat applications: improved stability through reduction of polyunsaturated fatty acids (in particular linolenic acid) and increased content of stable fatty acids, or use of non-hydrogenated solid fats or fully hydrogenated oils. Low-linolenic and high-oleic acid oils have been developed using crop-breeding and genetics.
Linolenic acid, while a “healthier fat,” is a negative for deep-frying, as it is one of the first lipids to oxidize and subsequently cause flavor defects, polymerization byproducts and reduction of smoke point. However, reducing linolenic acid enhances the lifespan of the frying oil and reduces rancidity in the stored product.
When solid fats are preferred, partially hydrogenated fats—the previous mainstay of deep frying—have been replaced with vegetable oil blended with fully hydrogenated vegetable oils or tropical plant-derived saturated fats, specifically from palm or coconut. A similar replacement strategy has occurred for substitution of shortening or partially hydrogenated margarine for baked goods and laminate doughs.
To achieve the appropriate melting temperature for fats, a number of technologies are performed by fat and oil manufacturers to accurately target the melting temperature to the application. Fractionation, for example, uses the variable melting temperatures of the different triglycerides within the fat or oil source. By carefully adjusting the temperature of the fat, the liquid and solid fats can be separated by filtration or centrifugation, allowing for tailoring of melting point to very specific ranges.
Another process, interesterification, can be used to “even out” the melting points of certain fats. Typically, interesterification takes a hard fat and liquid oil; then, using enzymatic or chemical methods, it removes the fatty acids from the glycerol backbone and randomizes the order and replacement of the fatty acids into the triglyceride molecules. Interesterification smooths out the sharp, defined melting points of different fat stocks, allowing for improved functionality and melting points more in line with the targeted application.
There has never been a more diverse time in the oil sector. Olive oil use continues its strong growth trend. Although some applications are unsuited to the extra virgin form, with its low smoke point (see chart, “Culinary Oil Smoke Points”), it’s not often recognized that standard olive oil has a smoke point almost as high as other oils used in high-temperature processing. More so, oil manufacturers have been developing blends that provide the technical abilities needed for processing with the health benefits of olive oil, maintaining the natural antioxidants which protect the oil’s stability. These compare quite favorably to soy and palm oils.
Culinary applications for finishing and dressing oils introduced offerings such as oils from avocado, grapeseed, argan, hazelnut, pumpkin seed, macadamia nut and others. Some, such as avocado oil, have a high enough smoke point to allow them to transition to high-temperature processing. Many of these specialty oils—and even traditional oils, such as canola, sunflower and soybean—have gained unique applications by processors using expeller-pressed, natural oils without further stabilization, decolorizing and deodorizing.
Expeller-pressed oils typically have a depth of flavor that is typical to the plant source and can contribute unique flavor attributes to the product application. Expeller oils that have not been stabilized tend to have a shorter shelflife, as impurities that can accelerate oxidation have not been removed.
Tropical oils have regained a strong following for their unique high saturation and are major components in non-hydrogenated solid fat replacements for shortening and lard. Coconut oil technically has a very high saturated fat content, but it also has a unique fatty acid profile, comprising a high percentage of medium-chain fatty acids.
Medium- and short-chain fatty acids are absorbed directly into the intestine and carried to the liver for metabolism to energy, whereas long-chain fatty acids enter the body through transport into the lymph system. This means coconut oil is considered a healthful saturated fat. It has a strong following in the health food sector because of the perceived benefit on metabolism, and consumers substitute coconut oil for traditional vegetable oils.
Palm oil has its followers in the health food sector, as well. Traditional red palm oil, or palm mesocarp oil, has extensive traditional use in Africa, South America and South Asia. Red palm oil, as its name suggests, is a vibrant red color from carotenoids from the mesocarp tissue of the palm seed. Red palm oil has traditionally been used as a source of vitamin A precursors and has extensive use in traditional medicine. It also is a primary source of vitamin E as tocotrienol, a form that is receiving attention for healthful benefits apart from those related to the tocopherol form.
However, the use of tropical oils has been controversial, aside from the saturated fat controversy. Global palm and coconut oil production has caused deforestation of key tropical forests. Sustainability strategies for production have been developed, and audit and certification schemes are in place for coconut and palm oils. However, some critics point to the need for producers to do more than simply compensate with extensive planting of more oil trees, noting the negative impact of the loss of diverse species. To address this, some manufacturers of African palm oil have focused on approaches that preserve diversity, as well as sustainability, fair trade and traditional farming methods.
Although obesity continues to be a major challenge in today’s society, fat apparently plays a more nuanced role in obesity and cardiovascular heath than many have assumed. Oil and fat in foods, when used strategically, can have a beneficial role in a healthy diet and delivers irreplaceable textural and flavor in foods. New ingredient technologies provide the flavors and benefits of traditional fats, while delivering a healthy benefit to consumers.