Fats and Oils Spread Out Possibilities in Margarine

August 2001

Fats and Oils Spread Out Possibilities in Margarine

By Scott HegenbartSenior Technical Editor

Although it was invented in 1869 as a substitute for butter, margarine not only survives to the present as a product, but continues evolving to meet changing consumer needs. Today, margarines and margarine-like spreads are available for needs ranging from consumer desire for more healthful foods to the specialized manufacturing needs of food processors. Although the processing method also plays a significant role, the many varieties of margarines and spreads available often are the result of changes to the fat and oil ingredients used.

A general definition for margarines is water-in-oil (W/O) emulsions manufactured by dispersing an aqueous phase (consisting of some combination of water, milk, whey, salt or flavors) into an oil phase made up of fats and/or oils, along with emulsifiers and oil-based flavors, colors and vitamins. The exact selection of the various fats and oils along with the other ingredients is indicated primarily by whether the margarine is destined for use by the consumer, or designed for use by processors in manufacturing other food products.

In general, the category of consumer-grade products are not real sophisticated and are largely based on a combination of partially hydrogenated and liquid soybean oil, says Bob Wainwright, technical director for Cargill North America refined oils, based at the companys C+T subsidiary in Charlotte, NC. Then you have the industrial grade, which contains not only table-use products, but the high-tech margarines designed for baking or other specialty applications. These will be quite sophisticated with respect to design.

Looking at lipids Standard margarine contains at least 80% fat. Between 40% and 79% fat, the term spread is used in the United States. At less than 40% fat, U.S. standards of identity allow the use of terms such as diet, reduced calorie, or imitation margarine. To ease discussion, this article will use the term margarine generically unless discussing a specific feature of spreads or diet margarines.

As a major component, the fat will have a direct affect on margarine texture, flavor and stability. The two qualities of fat that affect these properties are the solid fat index (SFI) and the crystal structure of the fats used. Margarine ordinarily consists of at least two different fats to create the desired SFI. Using multiple fats also helps stabilize the crystalline structure in the finished margarine.

In general, U.S. margarine manufacturers will select fats with SFIs at 50°, 70° and 92°F. Fats with 50°F SFI typically comprise 10% to 28% of the spreads total solids. If the level is too low, the margarine will be too soft for molding into sticks. Too high, and the margarine will lose its spreadability and may cool unevenly.

At 70°F SFI, the fats occupy around 5% to 18% of the margarines solids and contribute consistent texture to the margarine and help it resist separation. As with 50°F SFI fats, too low a level will yield a too-soft product while an overly high level will make a firm, nonspreadable product.

Last, 92°F SFI fats take up to 3.5% of the margarines solids. These contribute a rich mouthfeel to the product, but melt away quickly. This quick meltaway will be affected if the level is too high and the finished spread could exhibit a waxy mouthfeel, instead.

Keeping the fat in line Although not technically fats themselves, emulsifiers often are derived from fats and are critical ingredients in a margarines fat system. The predominant emulsifiers in margarines are monoglycerides and lecithin. Manufacturers originally added them in the 1920s to minimize water separation and subsequent spattering when consumers used margarine for cooking. The full benefits of these emulsifiers, however, are much more extensive than water retention.

Because emulsifiers stabilize emulsions, they can contribute greatly to the ease of creating the emulsion when processing margarines. They also help maintain the emulsion over the spreads shelf life.Emulsifiers further enhance shelf life and contribute to margarine quality because of their effects on fat crystals. Margarine and spreads are at their best when the fat is crystallized into the beta-prime form. This has a smaller size than the alpha form, leading to a shiny appearance and smooth texture in margarine. The beta-prime form also is more stable than the alpha form. During margarine manufacturing, emulsifiers can accelerate crystal growth, which helps promote beta-prime formation. In the finished margarine, emulsifiers help prevent these beta-prime crystals from transforming into the beta form, which can lead to a grainy texture with time.

Emulsifiers also may make other contributions, depending on a particular margarines or spreads purpose. Well discuss these later when we look at some of these different margarines.

Process establishes properties The selected fat system works in tandem with the process to create the finished margarine. In some cases, such as when the fat level for a spread is below 52%, the desired product depends even more upon proper manufacturing to assure proper emulsion creation and stability, according to Wainwright. Assembling a margarine or spread involves variations on four basic steps:

Melting and blending the oils together with other oil-soluble ingredients, such as emulsifiers, flavors, vitamins or colors. This blend often is mixed under a layer of nitrogen to minimize oxygen exposure and, subsequently, oxidative degradation.

A separate vessel blends the aqueous phase. This will comprise water and/or milk, plus water-soluble ingredients, such as whey. Each of the two phases must achieve a specific temperature. The exact temperature of each will vary depending on its components and the desired qualities to be imparted to the finished spread, but the aqueous phase usually is a few degrees warmer than the oil phase.

When each phase is properly prepared, the water phase is added to the oil phase with agitation to form the desired W/O emulsion.

The emulsion is cooled through a scraped-surface heat exchanger (Votator®) where it solidifies and becomes plasticized. At room temperature, a typical margarine contains around 20% of the fats triglycerides as a solid with crystal sizes from 3 to 10µm. If these are too large, the margarines texture will be grainy. Too small, and the product will lack plasticity.

Either spreading the emulsion across the surface of a chilled drum or passing it through a scraped-surface heat exchanger will achieve the desired size range. Either of these agitated cooling systems will rapidly lower the margarine emulsions temperature and encourage the fat to crystallize into the alpha crystal form. Because this is the least stable form, continued agitation of the cooling system encourages the crystals to convert into the desired beta-prime form.

The cooled margarine is packaged into tubs or formed into sticks. Industrial margarines ordinarily are packaged into 50-lb. boxes.The finished packaged margarines are tempered by storing at a certain temperature before being distributed, sold and used. Proper storage throughout the distribution chain is essential to avoid conversion of the fat crystals to the beta form.

Spreading it to consumers Between the selection of the basic fat ingredients and adjustments to the processing conditions, it might seem that endless types of margarines/spreads are possible. Looking to the product use guides the selection from these numerous possibilities. For consumer spreads, cost, functional properties for cooking and baking, and the spreads nutritional properties guide the product form.

In the eyes of consumers, margarine has become a kitchen staple and they will not tolerate a spread sold for more than their anticipated price-point. Consequently, margarine manufacturers seldom use fats that take full advantage of fat-modification technology to keep costs down.

In general, the formulations are pretty universal with two typical components, says Wainwright. You have a partially hydrogenated structuring fat that is generally based on soybean. In table-spread, tub-type products, its normally around 20% of the formula. In a stick, itll account for half.

The rest of the fat will be a minimally processed, deodorized soy or cottonseed oil. Hydrogenated cottonseed oil traditionally was used in all-vegetable margarines because it helps induce and retain beta-prime crystals.

The combined solid-fat index of these basic building blocks generally should have a steep melting curve to provide good meltaway in the finished spread. The exact combination, however, will vary with the spreads form.

Stick margarines originally contained two or more hydrogenated oils with a distinct break in the melting point at 70°F for proper mouthfeel. These all-hydrogenated products were said to have many advantages for baking and cooking because they were more resistant to oxidation.When market demands required high polyunsaturate levels in the 1950s, companies modified these formulations to the current standard of using a selectively hydrogenated fat with unmodified liquid oils. With more liquid fat, contemporary formulas generally exhibit lower stability and shelf life for which proper emulsifier selection and the addition of antioxidants help compensate.

Soft/tub margarine appeared in the 1960s and contained higher levels of polyunsaturated fatty acids than stick margarines. Soft margarine was not really new at that time, however; most manufacturers knew that higher liquid- oil levels would yield a softer product. The innovation here was packaging the product in a tub and marketing it as being softer and more spreadable.

As with stick margarine, using all hydrogenated oils will increase oxidative stability and will retain a smooth surface when packaged. It also can, however, generate a firmer texture that is less spreadable. Although both stick and tub margarine must be spreadable, consumers expect tub margarine to spread nicely even when taken directly from the refrigerator. Consequently, soft margarines contain a higher ratio of liquid oil to hydrogenated fat when compared with stick margarine.

The high level of liquid oil in soft margarines results in a greater need for emulsifiers. With less crystal-forming solid fat available, the emulsifier helps the margarine retain its shape by promoting crystal formation and retention at these lower solid-fat levels. During manufacturing, a soft margarine also will be subjected to a longer votation period to make sure that as many of the correct, structure-forming fat crystals are formed as possible.

Liquid margarine has never gained the same popularity with consumers as the other forms. It does, however, enjoy sales because it fills certain niches. (Squeeze-bottle-packed liquid margarines are much more convenient at picnics and camp outs, for example.) It enjoys greater popularity as an industrial ingredient because the liquid form is ready to be metered and pumped without any additional melting.

As one might expect, liquid margarine contains a higher proportion of liquid oil for a lower SFI. Solid fat crystals, however, still are important for proper organoleptic qualities. To achieve this balance, liquid margarine undergoes a longer crystallization period than soft margarine to yield a product with all beta and beta-prime crystals. A beta-prime-predominant liquid margarine is possible without as much tempering, but a beta-crystal-predominant margarine tends to be less viscous and have better suspension stability. With the extra processing, these do tend to be more expensive to make.

Beyond taste and performance Although many food products now are touted for their healthful properties, margarines have one of the longer histories of foods that target that niche. Most notable is the promotion of polyunsaturated fats beginning in the late 1950s and early 1960s. Today, other issues dominate the health perception of margarines and spreads. Some consumers, for example, will look for oils they believe are more healthful.

Many consumers will think of source oils beyond soy, such as canola or sunflower oil, says Wainwright. Either of these oils are perceived as having a more positive nutritional image.

Of course, many consumers are less concerned with the type of fat than they are to overall fat content of their diet. The creation of tub margarine led the way to the creation of reduced-fat spreads. Some reduced-fat tub products contain as little as 20% fat with the remaining bulk created by the aqueous phase. At such low fat levels, however, emulsifiers and fat selection arent enough to build structure. In these cases, the aqueous phase may contain texturizers, such as gums and starches. Because they are so different, reduced-fat spreads present a manufacturing challenge, as well.

As far as this product category goes, the sophistication comes more on the end of processing, says Wainwright. It becomes more challenging as we keep reducing the fat content.

Inevitably, the amount of water will reach a point where the low-fat spread no longer will function for cooking or baking. For one reason or another, the more fat-like fat substitutes also cannot be used at the high levels required for spreads.

This is a potential shortcoming that cannot be overcome, says Wainwright. Some of these diet products have 40% or lower fat content and require that you make the consumer aware that this product simply is not suitable for cooking or baking.

Given these limitations, higher-fat tub margarine and traditional stick products still remain available. In fact, many consumers purchase reduced-fat products as table spreads, but keep traditional margarine on hand to use in recipes.

Following the trans trend Besides looking at the type and quantity of fat, consumers also are becoming more aware of any processing to which fats in a margarine or spread are subjected.

In their native state, fat triglycerides tend to have hydrogen atoms on the same side of the molecular chain in the cis configuration. Hydrogenating the oils places the hydrogen atoms on the opposite side of the triglyceride molecule in the trans configuration.Research has indicated these trans isomers may have even greater deleterious health effects than naturally highly saturated non-hydrogenated fats. This has led some consumers to begin avoiding products that have hydrogenated oils and some manufacturers to create products that fulfill this demand.

The typical approach to avoid hydrogenated fats is to use a blend of the hard fraction of palm oil and the hard fraction of palm-kernel oil to get the structure normally obtained with a partially hydrogenated soy, says Wainwright. This hasnt caught on yet in the U.S. due to the stigma against tropical oils.

Another limitation to marketing such products is that U.S. food regulations have no provision for no trans labeling. In 1994, the Center for Science in the Public Interest (CSPI) petitioned the FDA to require trans fat to be included with saturated fat on food labels. In 1999, the FDA proposed just such a rule, but has yet to enact it. Until these regulations are in place, some manufacturers are reluctant to make trans fatty-acid claims.

From a purely legal perspective, I believe the current no trans labeling is not really legal, says Wainwright, but so far nobody has been taken to task for it.

In June 2001, CSPI fired a letter off to the FDA to finalize the proposal for including trans fat on food labels. The letter, sent by 53 scientists to Health and Human Services Secretary Tommy Thompson, stated that trans fat raises blood cholesterol levels and promotes heart disease. Regrettably, the FDA still has not finalized its November 1999 proposal. Considering how many lives labeling of trans fat could save annually and the overwhelmingly favorable cost-benefit ratio, we respectfully urge you to take prompt action to ensure that trans fats are labeled, the letter stated.

A CSPI press release also claims that, according to the FDA, labeling trans fat would provide benefits worth $3 to $8 billion per year, while the costs would be only about $400 million initially and then no more than $144 million per year thereafter.

The Bush Administration likes using cost-benefit analyses to kill regulations, says CSPI executive director Michael Jacobson. In this case, the benefits so vastly outweigh the costs that Bush officials literally should be running to the Federal Register office with a final rule.

The organization also has sent a letter urging the Office of Management and Budget to make finalization of the trans -fat rule a top priority. The week prior to the CSPI letters, the Canadian government proposed a nutrition label similar to the one used in the U.S., but that includes trans fat.

Industry sources say that indications from the FDA are that a final rule on trans labeling may come sometime in August or September of 2001. The implementation deadline is expected to be Jan. 1, 2004.

Fat-based functional foods Contributing to the health profile of a margarine isnt achieved just by avoiding certain fat-related ingredients. It now also is possible to do so by adding certain fat-related ingredients. Plant stanols and sterols are found in and can be extracted from various plant sources. These substances reduce the absorption of cholesterol in the gut, which helps lower the concentration of cholesterol in the blood.

Unfortunately, sterols and stanols are crystalline solids that arent oil-soluble. Scientists found a way to address this limitation while preserving the ingredients cholesterol-lowering properties by esterifying the vegetable oils to form sterol and stanol esters. The conversion allows each to be combined easily into a high-fat system. Already, they have appeared in two spread products marketed in the U.S.: Ft. Washington, PA-based McNeil Nutritionals Worldwides Benecol® which contains stanol esters and Englewood Cliffs, NJ-based Liptons Take Control® which incorporates sterol esters.

Both products are really just a basic table spread, but have the functional sterol/stanol esters, says Wainwright. Those are the most prevalent developments were seeing in the retail spread category.

The FDA allowed both spreads on the U.S. market in 1999, but at the time never explicitly endorsed the products claims that they promoted cholesterol reduction. In September 2000, the agency concluded that the stanol and sterol esters did, in fact, lower cholesterol enough to reduce the risk of heart disease and issued an interim final rule on the active ingredients. The FDA reviewed several studies of the products to determine that eating at least two servings a day totalling 1.3 grams of sterol ester or 3.4 grams of stanol ester could significantly reduce cholesterol, as long as theyre part of a low-fat diet.

Unlike some nutraceutical ingredients, the sterol and stanol esters dont require a major product reformulation for their incorporation. On the contrary, they actually may prove helpful to spreads.

In the patent documents, some of these stanol esters actually can contribute some structuring effects, says Wainwright. Whether its stanol or sterol esters, they can affect the structure and mouthfeel and could even be selected to give a desired effect.

Not for home Margarine designed for home use faces the daunting task of balancing function with consumers nutritional demands. In margarines designed for industrial use, functionality is the primary rule. Most industrial margarines are designed for the special needs of baking. They usually possess a more complex fat system consisting of more than two fats. These fats will cover a broad spectrum of melting curves and solid-fat indexes.

As far as source, most of these will be soybean, says Wainwright. Sometimes, you need a beta-prime contender in there, so you see a cotton or a palm with some beta-prime tendencies in them. We dont see too much canola or sunflower in this category.

As with consumer margarines, selecting the correct source oils doesnt complete the task. How those oils are processed also helps impart the desired performance to the finished product.

How we crystallize the emulsion directly affects the plastization of the margarine, says Wainwright. There often will be a specific tempering cycle where the margarine will be maintained at a slightly elevated temperature (depending on the application) for two to three days. This allows that crystal matrix to develop and create the ideal consistency so that product can be pumped/extruded or rolled in.

Generally, industrial margarine formulations will resemble those of the firmer stick margarines sold to consumers. Manufacturers adjust the firmness and plasticity through fat selection and processing to suit the specific type of products for which the margarine will be used.General bakery margarines will have a flatter melting curve for a wider plastic range. This will give them good creaming properties, much like an all-purpose shortening. Good plasticity also is important if the margarine will be used as a base for buttercream frostings, which require a smooth texture.

Roll-in margarines make up the rest of the industrial margarines and are further subdivided into margarines for danish, croissants and puff pastry all laminated products, but with individual margarine requirements.

Generally, plasticity and firmness are the major features of all roll-in margarines. Plasticity helps ensure that the margarine can retain an unbroken layer during lamination. Firmness is critical because margarine that is too soft and oily will not create the proper barrier between dough layers and may even be forced out by processing pressure. The margarines for these applications will be tough, extensible and relatively high melting. They must not, however, be so firm that they tear the dough during the multiple folds and reductions experienced during lamination.

If that werent enough, the margarine also must be able to retain these qualities even when its pumped and extruded during processing. Sometimes, these pressures are so great as to squeeze the water right out of a margarines emulsion.

These margarines are more aggressively hydrogenated to make them more robust, says Wainwright. The structuring component will be highly hydrogenated. The remaining oils also will be hydrogenated, but to a lesser degree. At times, the formula may require using all solid fats.

The softest roll-in shortenings are designed for danish and increase in firmness for croissants and puff pastry, respectively. Not only do danish and croissant margarines have to meet the criteria above, they have to be firm enough to survive proofing prior to baking. At the same time, they must yield products that have the desired soft texture.Puff-pastry margarines, on the other hand, generally are more waxy. Although this mouthfeel often does transfer to the finished product, brittle layers and a lingering fatty mouthfeel are expected organoleptic properties, in this case.

Some of the puff-pastry margarines are hard and brittle and can have a 120° to 125°F melting point, says Wainwright. You have a very thin dough in these products, so you need that extra structure to really hold it together.

From eating qualities to functional properties, fats and oils truly make margarines and spreads all they can be. Although the various margarine forms have widely divergent needs, the manipulation of the fat content along with processing adjustments provides a vast array of potential solutions. These possibilities will, no doubt, keep margarine formulators busy for years to come.

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