Fat and Oil Fundamentals
It was a few more years before the gap between healthy fats and non-healthy fats filled in (by increased research coupled with consumer education) to the point where a clearer understanding emerged. For the most part, nearly all the lipid sources in human foodstuffs are, or at least can be, a positive contribution to well-being.
All organic fats and oils are chemically similar, composed of triglycerides in a solid or liquid form that depends largely on the structure of each of the molecular components. Those components are a glycerol backbone with three fatty acids attached. The chemical structures also determine how healthful (or not) an oil will be, once ingested.
Rudimentarily speaking, the healthfulness of an oil is considered in terms of how it affects the balance of lipoproteins—essentially the transport form of lipid (oil) in which it is “captured” in a microscopic blob (and now termed “cholesterol”) surrounded by protein molecules—through the bloodstream. Research into diet and disease, especially cardiovascular disease, has indicated that the amount of high-density (HDL) versions of these blobs (more protein than oil) vs. low-density lipoproteins (LDL) correlates with risk for disease. More LDLs than HDLs, higher disease risk, and vice versa.
To that end, when more attention was being paid to what people ate that affected those rations, it was initially noticed that saturated fats, in which all three fatty acids are as full of hydrogen molecules as possible, seemed to push the percentage of LDL cholesterol in the blood higher. The rush was on to remove saturated fats. But, there were a couple of flaws with this approach, one industrial and the other physical.
From the food processing side, saturated fats were more convenient to many formulations, especially baking formulations. They performed better in recipes and added flakiness to crusts and creaminess to mouthfeel; plus, they are more stable and easy to ship, store, measure and include in processing. Saturated fats, predominantly from animal sources (think lard, beef tallow, butter), as well as certain plant sources (specifically, the tropical ones palm and coconut), are hard at room temperature.
To Saturate, or Not to Saturate
On the health side, later research suggested that, contrary to previous belief, naturally saturated tropical plant fats do not have the same impact on blood cholesterol levels and ratios as those from animal sources. Other vegetable fats (from corn, soy, cottonseed, sunflower, safflower, peanuts and, by the 1980s, olives) were liquid at room temperature—their fatty acids not completely saturated with hydrogen. Being unsaturated fats, the looser structure kept them from solidifying.
Luckily, vegetable fats could be turned into hard fats—that is, shortening—by saturating those unsaturated fatty acids with hydrogen. Hydrogenation, however, was not thought to affect the health profile of the vegetable oil. The tide shifted to the use of hydrogenated oils. Another way to create a solid oil was to borrow a trick from nature. In unsaturated fats, the gaps where a hydrogen atom is missing are predominantly on one side of the fatty acid, causing it to bend and make the structure loose, keeping the lipids from solidifying. But, small amounts of unsaturated fats in nature have the empty spaces on alternating sides of the fatty acid, which keeps it straight, allowing it to condense and resemble a saturated one. The result is a trans fatty acid.
Partial hydrogenation took advantage of this to create trans fatty acid products that seemingly kept the processing benefits of a solid fat and the health benefits of an unsaturated one. However, research dating back to the 1940s showed that trans fats were not only worse for the body, when it comes to heart disease risk, but also quite possibly could increase the risk of cancer.
By 2002, enough controversy surrounded the presence of trans fatty acids to warrant the National Academy of Sciences, in their Dietary Reference Intakes recommendations, to declare them “more deleterious with respect to coronary heart disease” than saturated fats. The following year, the FDA legislated mandatory labeling of trans fatty acid content; it became law in 2008. This was all but the kiss of death; since the ingredient received so much negative publicity, processors rushed to get trans fats out of formulations.
Trans in, Trans out
“The move to reduce or eliminate trans fatty acids from common baked goods presented some formulation challenges,” explains Mark Daloia, a commercial baking consultant and owner of Cucina Verde. “On the surface, this looks relatively simple—just replace the partially hydrogenated shortenings with trans fat-free shortenings. In reality, things are more complicated than that. Part of the issue with the zero trans fat shortenings is their structural stability. For instance, in the case of preparations such as frosting, the shortening is a structural component that helps contribute body; entraps air to make the product fluffier; and helps the product hold shape when spread on a cake or used to make decorations.”
“The transition to hydrogenated fats a generation ago was the easiest change-over in baking,” adds Daloia. “In fact, the switch to these hydrogenated fats ended up improving the products. At that time, saturated fats were the big health issue. Switching to hydrogenated fats was so basic, in many cases taking difficult processes and making them simple. When hydrogenated fats came out, you could cut your learning curve on creating cookies and cakes. Before hydrogenated fats, you had a specific order in which you had to add ingredients; after hydrogenated fats came on the scene, you could add them any point. For example, pound cake, as simple as it is in formula, you had to know how to put those few ingredients together, each at the correct stage. With hydrogenated fats, you could just throw all the ingredients in a mixer together. Losing hydrogenated fats put many processors back to Square One.”
Daloia goes on to explain that zero trans fat shortenings tend to be less tolerant of heat and were often softer at ambient temperatures than the partially hydrogenated shortenings they are replacing. This reduces the structural integrity of the frosting, leaving it looser and softer. It also makes it more difficult to whip in air. To compensate for this, zero trans fat shortenings must be stored in such a way that they do not get too hot either prior to, or during, use. Also, care must be taken not to over-mix the recipe, since the mixing process contributes heat, thereby reducing the structural functionality of the shortening and causing it to break down.
“Hydrogenated fats and oils are more tolerant in this respect,” says Daloia. “When working in a hot environment, there are major changes needed to maintain the structural quality of a finished frosting product. This can mean changing the way the shortening is stored; adding ice or chilled water to control temperature during mixing; or using a jacketed mixer with cooling to reduce the product temperature during mixing. In many plants, these are major changes that might be difficult or impossible to accommodate, either due to lack of specific pieces of equipment or temperature-controlled storage space.”
There are several answers to the challenge. Additives can be used to reinforce the structural features of a zero trans fat frosting. These could include ingredients that help control water, such as hydrocolloids, or fat-structuring ingredients that have recently been turned to use in zero trans fat formulations. The addition of mono- and diglycerides (glycerol backbones with only one or two fatty acids attached) at low levels do help with the stability and tolerance. These agents help contribute structure by either reducing the heat sensitivity of the shortening or by tying up water in the formulation.
Oils, New and Renewed
Two popular substitutes for trans fatty acid-containing hydrogenated shortenings include interesterified oils and tropical oils, usually palm oil. Interesterification of fat trades out an unsaturated fatty acid for a saturated one in the middle of the glycerol backbone. Plugging it into the middle, instead of into the first and third position (where it would naturally be), turns out to be different from merely creating a saturated fat from an unsaturated one. The body actually digests and metabolizes the fat molecule differently. Research also suggests this leads to no significant change in blood lipids; apparently, the body treats the molecule as it does a non-interesterified version of the same fatty acid.
Palm oil has enjoyed a big shot in the arm from the dropping of trans fatty acids from formulators’ ingredient lists. At first pilloried for being a saturated fat, scientists delved deeper and found that, unlike animal-derived saturated fats, palm (and coconut oil—and cocoa butter, etc.) doesn’t appear to increase LDL levels. There was a slight hitch when, in ramping up production, questions of sustainability and ecological damage arose. Most palm oil comes from Malaysia in ecologically sensitive regions. However, many palm oil producers and authorities are working with conservationists in efforts to address these issues, and changes have been quick to come.
According to watchdog group Greenpalm.org, “Oil palms are highly efficient oil producers, with each fruit containing about 50% oil. As a result, they require ten times less land than other oil-producing crops.” The group points out that palm oil (and palm kernel oil) also are non-GMO products. The group provides information, guidance and support to the palm oil industry for the production of a sustainable, eco-friendly product. The group reports that palm oil now makes up one third, or nearly 50 million tons, of the vegetable oil produced globally.
Also making up a third of the vegetable oil that is produced is soybean oil. Soybeans and seeds are still the premier source of cooking oils and fats in the U.S. Because of this, growers and manufacturers are aware of its impact on the American diet and its status as a vehicle for improving lipid nutrition across the board. Some of the key advances in soy oil include the development of high-oleic forms, through natural cross-breeding, that are lower than ever in saturated fats and higher in alpha-linolenic acid, the plant form of omega fatty acids. According to the United Soybean Board, “While fish oil is the preferred source of omega-3s, because of the bioavailability of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the alpha-linolenic acid (ALA) in soybean oil is one of the few non-fish sources and the principal source of omega-3s in the American diet.”
Another major source of vegetable oil in the American diet is from canola. Canola, too, has been developed to be higher in healthful oleic acids. There are a number of other benefits to using canola oil.
“Canola oil has the least saturated fat of all popular cooking oils—half that of olive and soybean oils,” says Cory McArthur, vice president of the Canola Council of Canada. “[It also has] a high smoke point, 468˚F, making it ideal for high-heat applications. Its versatility, neutral taste and light texture are additional assets in the commercial kitchen.” McArthur also notes that high-stability (high in monounsaturated oleic acid) canola oils are available to the commercial food sector. “These specialty oils have an even higher heat tolerance—475˚F—and longer fry and shelflife than commodity canola oil,” he explains.
Canola products also are making more inroads into baking formulations. “There are several solid fat products available to the commercial food sector that include canola oil as part of a blend,” says McArthur. “This allows [processors] to reduce the saturated fat without losing the texture required for certain baked goods. Some of these products also offer the advantage of being free of trans fat.”
Canola is clear and stays fully liquid, even down to 41˚F. Oil researchers also are working with high-omega-9 canola oil combined with high-oleic formats in order to create new interesterified versions that allow improvement in melting profiles.
Sunflower oil is a high-oleic (minimum 75% oleic) monounsaturated oil with excellent stability, and safflower oil is a very light, nearly colorless product high in polyunsaturated fats. In fact, among vegetable oils, safflower has the highest percentage of mono- and polyunsaturates, as well as one of the highest smoke points (at 510°F), making it highly preferred for frying.
Olive oil, too, is seeing wider use in manufacturing. This most ancient of oils could be said to be responsible for building civilization—as one of the oldest cultivated fruits, it boasts a 12,000-year history, being used for oil, food and lamplight, effectively powering life in the Fertile Crescent. Yet, its use in batch frying didn’t take off until recently. But, with health benefits verified through thousands of studies over decades of research, and a rich, umami flavor, it quickly found itself in scores of fried and baked snacks.
A relative newcomer on the scene is avocado oil. Good Health Natural Products Inc. recently became the first food manufacturer to use avocado oil to cook potato chips. The company developed proprietary technology to kettle-cook potato chips with avocado oil without transferring high fat content. On top of all that, avocado oil gives fried foods a unique, rich buttery taste. It also is a source of healthy phytochemicals.
“Avocado oil is very high in phytosterols, particularly beta-sitosterol, with about twice as much as is in olive oil,” says Mark Gillis, CEO of Good Health. “Phytosterols, in conjunction with monounsaturated fats—which avocado oil is very high in—have been shown to lower LDL cholesterol levels by a significant percentage.” And, that makes it another important oil in the arsenal of healthful fats food makers are employing to change the way people perceive—or rather, misperceive—the role of fat in the diet.
One pathway in the rush to make healthier fats involves the chemistry of indigestible fat. After 25 years of experimentation and development, the result of such research is a large, 6-8 fatty acid structure made from soy oil and built on a sucrose backbone, without having to use trans fatty acids. This “macromolecule” of a fat “substitute” functions, looks and performs in processing as an ordinary fat, and products made with it are organoleptically identical to products made with standard fats. The body, however, does not recognize it, and so it is not metabolized. After 15 years of successful use, patent-holders reformulated the product. Today’s version is available in multiple forms, for baking, frying and even using in butter substitutes, as well as a shortening that allows for a reduction of up to 75% of the calories from fat in recipes. In some formulations, oils made from this indigestible lipid can even be substituted for 100% of the oil in a standard recipe.
Oils “Go Good”
As research into the health value of unsaturated fats was ramping up, the connection between polyunsaturated and monounsaturated fats—such as in fish oil, olive oil and nut oils—was showing these lipid sources to not only be superior for preserving and improving heart health, but preventing a host of other diseases and conditions. Omega-3 fatty acids, sourced not only from fish but now from aquatic sources as diverse as krill, algae, seaweed and, recently, New Zealand green-lipped mussels, have piled on study after study in the past couple of decades—proving that, in most respects, they really are “all that,” when it comes to protection against disease. Omega-3s were an obscure chemical term 20 years ago; in July, the 19th annual United Soybean Board “Consumer Attitude About Nutrition” survey revealed that 84% of Americans recognize omega-3s as a healthy fat. It’s all great timing. Science is making fat’s position in health clearer, while technology is making it possible for food and beverage makers to utilize new forms of the ingredient that can enhance this newly acquired position.
Something all food oils have in common is a tendency to go rancid, leading to off-flavors and aroma, as well as diminished performance. Heat, light and air all contribute to rancidity, with unrefined oils having a lifespan of as short as a few months. (Refining can double the shelflife.) Cold-storing oils in airtight containers away from light slows the rancidity process down, also doubling the life of the product. The more solid or saturated an oil is, the slower it is to turn rancid, with some products able to last a year or longer. When keeping oil in cold storage, it will thicken and can even cloud, but this will reverse after a short time at room temperature. Other methods for keeping oil from going off include the use of antioxidants, especially tocopherols (vitamin E), or removing air from the oil container and substituting nitrogen or some other inert gas.
For processors using solid shortening but desiring more convenient handling, an alternative exists in the form of flaked or powdered shortening products. Powdered and flaked fats are more easily weighed and measured, and thus able to be applied more accurately to formulations. Powdered shortenings are free-running; take up less packaging and storage than liquid or block shortenings; thus, reducing labor costs and waste. Because of a smaller particle size and increased surface area, flaked and powdered shortenings are fast-melting, and they allow quicker mixing and a more even distribution, without clumping, of fat particles in a dry mixing process.pf