Article: Functional Benefits of Trans and Saturated Fats -- January 2008
The Benefits of Trans and Saturated FatsHistorically, animal-derived lipids with significant quantities of natural trans and saturated fatty acids were the primary oil and fat products used by man in food preparation. Traditionally prepared Yorkshire pudding made from animal fat drippings or refried beans and piecrusts made with lard are centuries old comfort foods with desirable textures based, in good part, on the fats they contained.
Lard, however, contains roughly 42% saturated fats. It has a melting point in the range of about 30°C. Its Solid Fat Index (SFI), the percentage of fat triglycerides in a crystalline phase (solid rather than liquid) versus total fat across a temperature gradient, shows that some 49% is solid at 10°C but only 2% at 40°C. Butterfat’s melting range is also very roughly 30°C and has a similarly sharp melting curve, with 47% solid at 10°C dropping to 0% at 40°C. Compare these to traditional unhydrogenated soybean oil, which melts at about -16°C.
This soybean oil has a healthier fatty acid profile than lard, so why is it not used in puff pastry products, for example, instead of fats with high levels of saturated fatty acids? Quality puff pastries are expected to have light, airy textures. Solid fat, layered in during the sheeting process, facilitates the formation of layers of dough between thin fat layers. A liquid fat will mix into the dough, rather than aiding the formation of separate layers. During baking, water in the dough layers turns to steam and expands. Melting fat forms a barrier that hinders steam from escaping. Even in products such as danishes and croissants—that primarily rely on the formation of air pockets from yeast—the ability of fat to impede escaping steam is important for their aeration.
However, it is not just the presence of a fat or oil that is critical; their solid fat content is crucial. The 2001 book Bakery Problems Solved, by Stanley Cauvain and Linda Young, reports that it is important to control processing temperatures in the production of puff pastries. They advise, “For example, butter has a low solid fat index at 20°C, and pastes made with all butter benefit from processing at temperatures around 12-14°C, which gives workable fat layers, but that will not be so brittle as to break during sheeting.” Further advice in regards to fat use and providing “lift” in puff pastries includes:
A higher solid fat content does not mean a better end product, however. The book notes that a waxy texture, often described as “palate cling,” occurs with too high a solid fat content at 40°C and suggests that laminating fats should have 5% or less solid fat at 40°C.
Such fats with sharp melting points, particularly around body temperature (98.6°F/37.0°C), are desirable for a range of applications. This “melt in your mouth” phenomenon is expected in quality chocolates, for example, and is a key benefit of many tropical oils. (See chart “SFI of Various Oils and Oil Blends.”) Many have experienced the sensory disappointment that comes with eating a decorative confectionery topping a cake, which appears to be chocolate, only to find it crumbles to tasteless “wax” in the mouth, due to fats that remain solid.
Beneficial solid fat indexes have not been limited to natural fats and oils; they have been one of the benefits of hydrogenation and the newer interesterification technologies as well.
Advances in HydrogenationThe oil hydrogenation process, first patented in the early 1900s, hardens plant and fish-derived oils, allowing them to be effective replacements for hard animal fats. Hydrogenation technology has advanced through the years. As one presentation on PreparedFoods.com notes, many different types of products can be produced by controlling certain factors. These include the type of starting oil, temperature, time and the type of catalyst used. Finished textures can range from liquid to a “brick” in hardness. (To hear and view the 2005 presentation, type “Trans Fat Reduction Platforms Frank Kincs”—minus the quotation marks—into the search field at www.PreparedFoods.com.)
For example, another presentation on the subject notes that a lower level of hydrogenation is used for partially hydrogenated winterized salad oils, more hydrogenation is needed for creamy liquid fry shortenings and even more for cube shortenings. (To hear and see the presentation, type “No Trans Fat for 2006,” while leaving in the quotation marks, into the www.PreparedFoods.com search field.)
Hydrogenation makes oils firmer both by adding hydrogen to double-bonded carbon atoms in fatty acid chains and by creating double bonds in the trans-configuration. (See chart “Fatty Acid Melting Points.”) As pointed out by the “Trans Fat Reduction Platforms” PowerPoint presentation, hydrogenation decreases iodine value (a saturation measurement); decreases double bonds, particularly in C18:3 and C18:2 fatty acids; and increases stability by increasing mono-unsaturated and saturated fatty acids, particularly C18:1 and C18:0 fatty acids. The formation of trans C18:1 contributes to a sharper SFI or SFC (solid fat content) slope line, making it more useful for certain applications. (The sidebar “Shorthand Fatty Acid Names” explains how to interpret these fatty acid notations.)
The contribution of trans fatty acids to hardness can be seen with mono-unsaturated oleic acid. When the oleic double bond is in a cis-configuration, the fatty acid melts at about 15°C; when it is in a trans configuration, its melting point is increased to about 42°C.
Yet another video presentation from 2005 lists types of vegetable oil-based ingredients that meet specific needs of the food manufacturing industry. (Type in “Fats and Oils Joe Higgs vice president,” without quotes, at www.PreparedFoods.com). The ingredients include bakery shortenings, which could be categorized as all-purpose; emulsified shortenings (which typically incorporate mono- and diglycerides at 3-4%) for cakes and icing, for example; and fluid shortening for use in bread applications. Fry-type shortenings (available in both solid and liquid forms) are partially hydrogenated fats that are useful in applications, due to their improved fry life.
Other common vegetable-based oils include regular margarines, which have a standard of identity that means they must contain at least 80% fat by weight. Butter can be blended in up to a level of 50%, at which point the blend becomes cost prohibitive, notes Joe Higgs, the presenter. Spreads used primarily for spreading on breads can have less than 80% fat and may also contain small amounts of butter. Liquid margarines typically also contain 80% fat. They have 2-3% solids at most. They are processed to have a low viscosity and, if structure is not needed in a finished application, they are a good alternative to obtain no-trans finished products, Higgs adds. Aerosols must be liquid, since they are applied by spraying.
Higgs reminded his audience that trans fat-free products—both solid and liquid—are made from a variety of fats and oils. Trans fat-free shortenings are usually formulated with oil blends that use components such as fully hydrogenated fat (which contains no trans fats, since there are no unsaturated bonds), salad oils and/or tropical fats (i.e., palm, palm kernel and coconut). Palm, in particular, is still one of the best functional equivalents to partially hydrogenated, all-purpose or cake-and-icing shortenings from a functional point for baking applications, he says.
A number of other options to address the trans fat issue also exist. They range from simply eliminating trans fat ingredients, regardless of the quality of the finished product, to the use of interesterified fat and oil blends. For up-to-date details on these options, view the webinar “Exploring Trans Fat Solutions” by typing that title into the search field at www.PreparedFoods.com.
Elimination to InteresterificationIn working towards reducing or eliminating trans fats, a number of decisions must first be made. They include understanding what is required for fat/oil functionality; processing requirements, cost and logistics (i.e., locations, tanks, segregation, lead times); positioning of the finished product (i.e., is it a line extension or replacement?); and determining acceptable ingredients (for example, tropical [or animal-derived fats]), notes Frank Kincs in his presentation “Trans Fat Reduction Platforms.”
When trans fatty acids are removed, the solids they contribute to a formulation will decrease unless replaced. When the solids are replaced, it will be with saturates, notes Kincs. He offers alternatives to traditional hydrogenated fats, some of which can be categorized as follows:
Gary List, one presenter in the “Exploring Trans Fat Free Solutions” webinar, states that enzymatically interesterified products are now commercially available and cost-competitive. They can be used for applications such as soft tub and spreadable stick margarines and spreads, bakery margarines and all-purpose baking shortenings for cakes, pies, icings and cookies. In communications with certain individual suppliers, the FDA’s stance towards the labeling of interesterified fats has been to allow their labeling as “interesterified” rather than “hydrogenated.”
These technologies provide advantages beyond trans fat-reduction. For example, a 2004 Frost & Sullivan Market Insight report entitled “Growing Demand in the Specialty Fats Market” predicts increased interest in cocoa butter alternatives. Factors such as an unstable political scenario in Africa’s cocoa bean-producing areas, an E.U. directive and an Australian regulation now allowing vegetable-based oils to be used in products marketed as “chocolate,” in addition to a growing consumer demand in China and Brazil, means an increased demand for fats that closely mimic cocoa butter’s fairly unique melting profile.
In the area of frying oils, Kincs says foodservice operations are looking at reducing trans fats, most often by blending them with other fats, rather than complete elimination. However, Kincs’ presentation, given towards the end of 2005, could not predict the aggressive stance local governments are now taking in regards to trans fats.
A Studied Approach for Reduced Trans FatsNew York City is one of a growing number of municipalities striving to remove artificial trans fats from their citizens’ diets. Additionally, Merlin Development’s Skarra notes (in her podcast) that the effort to remove all artificial trans fats from all applications means the most difficult tasks still lie ahead. The more easily accomplished removals have already been completed. Additionally, “For perspective, we’re not just replacing one fat with another, we’re replacing a category of ingredients that has been developed and optimized over a 50-year time frame,” she says. The food manufacturing industry has optimized food product attributes, processes and distribution to take full advantage of the characteristics delivered by traditional hydrogenation. “Replacement of that ingredient, while maintaining quality, line speed, shelflife and cost, will not be easy,” she adds.
Her podcast offers a thought-provoking “roadmap” to achieve more effective planning and resource utilization, while obtaining realistic objectives and timeframes. For example, acknowledge difficulties and prioritize objectives. Remember the axiom that faced with the triple goal of developing a new product “good, fast and cheap,” one can pick only two; and for New York City, “fast” has been mandated by the July 2008 deadline, Skarra notes.
“Select your best technical approaches and your supplier partners. The short time frame dictates that most manufacturers will prudently limit themselves to off-the-shelf ingredient options that are available in full-scale quantities. If the manufacturer and the shortening supplier are developing [new products] simultaneously, the risks of complications increase greatly,” Skarra adds.
Further suggestions involve considerations as to the impact that trans fat alternatives may have on production lines, distribution and product storage, and the use of trans fat alternatives in low-volume SKUs.
Skarra points out what many experienced formulators have learned. Much work is often still required after the project has been “completed.” The rush to meet a deadline does not necessarily mean that “slapdash” work was done. However, resources will be needed to resolve the quality problems that are highly likely to emerge due to “system smoothing.” For example, this could include resolving issues that are the result of marginal decisions that may have been required and to facilitate cost optimization. Of course, advances in nutritional understanding and new efforts by consumer advocates pushing for change mean it is advisable to take the longest view possible in choosing ingredient optimization approaches.