Painting Better Greens

Painting Better Greens

By Donna Berry 
Contributing Editor

Photo: Cherry Marketing Institute

Use a starch-based system in a cherry-walnut vinaigrette to reduce the oil content while maintaining viscosity. This type of application needs a starch that remains clear in solution.

Experiment number one: Pour a small amount of fat-free, creamy-style dressing on a plate and let it sit out at room temperature, uncovered overnight. Try to clean the plate the next morning. What one finds is that rather than washing off, it peels off, much like dried latex paint on a non porous surface. This should be no surprise, as fat-free creamy dressings and latex paint both consist of polymers suspended in water.

Experiment number two: Try the same experiment with a light or reduced-fat dressing, as well as a full-fat, traditional dressing. Result: They do not peel. They wash clean.

“It’s the oil,” says Paul Tutt, director, Enova™ brand for ADM Kao LLC, Decatur, IL. “Fat provides a lubricity and mouth-feel that is unmatched by any fat substitute. This is one of the reasons why fat-free dressings have struggled to achieve broad consumer acceptance, and the lighter or reduced-oil dressings are becoming more common.”

Before you start removing oil in dressing, it is important to be aware that the term “salad dressing” has a standard of identity. The Code of Federal Regulations (CFR) states that products labeled “salad dressing” (21CFR169.150) must contain 30% vegetable oil and 4% egg yolk, by weight. There also is a standard for French dressing (21CFR169.115), which requires it to contain 35% vegetable oil. Thus, to be compliant, manufacturers must be careful to properly use the familiar term “salad dressing” on product labels. It is likely more accurate to simply use the term “dressing.”

When lowering the oil content, the Nutrition Labeling and Education Act (NLEA) enters the name game. To be called “reduced-oil dressing,” the product must contain a total of 25% less fat than the “regular” formulation. Again, if the standardized term “salad dressing” is used, rather than simply “dressing,” the product must also contain 4% egg yolk. The same holds true for these other legal descriptors.

“‘Low-fat’ dressings must contain no more than 3 grams of fat per reference amount,” says Celeste Sullivan, senior applications scientist, Grain Processing Corp. (GPC), Muscatine, IA. “The established reference amounts are 15 grams for a spoon-able dressing and 30 grams for a pour-able dressing. Reference amounts have been based on a quantity typically consumed.

“In order to make a ‘light’ claim on a dressing, you must identify the reference food on the label and state the percent or fraction by which the fat has been reduced from the regular product,” says Sullivan. “If the standard dressing derives more than 50% of its calories from fat (as in most salad dressings), the ‘light’ product must contain at least 50% less than the ‘regular’ product. The ‘regular’ or reference food must be representative of the type of food bearing the light claim. Also, the nutrient value of the reference dressing must be representative of a broad spectrum of foods of that type. The regulations specify how the nutrient values (fat and calories) for the reference food are derived. One acceptable way is to average values from the top-three national brands.”

Getting through the legal jargon is the first step. Lowering oil content and still producing a palatable dressing that clings onto salad greens is the next.

Paul Sheldrake, market manager–liquid systems, Avebe u.a., Veendam, the Netherlands, adds, “One of the greatest innovations in the traditional mayonnaise and dressing market is clearly the introduction of starch-based stabilizers that allow for lower-oil-content products.

“Texture is one of the most important consumer features of dressings,” says Sheldrake. “A traditional full-fat dressing has a short cuttable and spoonable texture that arises from the packing effect of the emulsified oil droplets. The food technologist needs to bear this in mind when developing a lower-fat alternative. Potato- or maize-based starches, for example, are a good choice as they tend to give a shorter texture, while those from tapioca tend to be longer.”

According to ACNielsen Label- Trends™, some oil definitely helps, and when it comes to legal definitions, “reduced” seems the way to go. In 2005, sales of reduced-fat pourable dressing were up 6.6% from 2004, to $116.4 million. Low-fat dressings were down 10.1% to $21.3 million, while fat-free dressings sales decreased 2.4% to $20.4 million.

For the most part, when consumers choose reduced-fat, they know they are making a healthier choice without much sacrifice.

Indeed, “Oil provides viscosity, shortness and texture to dressing, along with a rich, premium eating quality,” says Sullivan. “Lubricity and creaminess are attributes that are hard to find elsewhere. In creamy dressings, the oil emulsion contributes to the desirable opacity.”

“And if you choose certain oils, a dressing designer can add value that just is not possible when no fat is in the formula,” Tutt adds. “For example, Enova brand oil is the first salad oil clinically shown to help consumers maintain a healthy weight and lifestyle when used as part of a sensible diet. When you metabolize the fat in Enova oil, much of the fat is sent to the liver where it participates in betaoxidation pathways and is used more readily than stored fat.”

Enova oil is manufactured through a process that starts with soy and canola oils, so the product has a light, neutral taste that doesn’t mask the flavors of other ingredients. The component that makes it stand out from other oils—diacylglycerols (DAGs)—is initially present only in small quantities. Through a patented process, ADM Kao LLC, a joint venture between ADM and Kao Corporation, Tokyo, converts the predominant triacylglycerols (TAGs) in natural soy and canola oils into a mixture that is at least 80% DAGs. TAGs carry three fatty acids on a backbone molecule; DAGs carry only two fatty acids. They are either in the first and second positions on the backbone (1,2 DAGs) or in the first and third positions (1,3 DAGs). Enova oil consists of 80% DAGs; 70% of these are in the 1,3 form.

“The body breaks down Enova oil and traditional TAG oils in the same way and absorbs the resulting fatty acids into the intestine,” says Tutt. “Then the intestine rebuilds the fatty acids into fat molecules and combines them into packets called chylomicrons that are sent to the bloodstream, to be stored in body tissues. Due to the shape of the 1,3-DAG molecules, enzymes in the intestine cannot efficiently recombine the pieces of this fat into fat molecules, so less fat is passed into the bloodstream to be stored in the body.”

Enova oil is generally recognized as safe (GRAS) for use in dressings and is virtually indistinguishable from conventional oils in final product applications. It is listed in ingredient statements as “diacylglycerol oil.” It is cholesterol free and an excellent source of vitamin E. It also has only about 4% saturated fat and zero grams of trans fat per serving. The next best conventional oils are derived from safflower, sunflower and canola, and range in saturated fat content from 6% to 8%. The omega-6 to omega-3 ratio in Enova oil is 10-to-1. Being an oil, it has 120 calories per 1 tablespoon serving, the same as other conventional oils. It is not a low-calorie oil; its point of differentiation is that, because it is metabolized differently than conventional oils, less oil is stored in the body as fat compared to other cooking and salad oils.

The benefit of using some oil is realized on the bench and at retail. “Dressing designers typically turn to starches and hydrocolloids to build back the body and viscosity that is lost when oil is removed,” says Sullivan. “Even a small amount of oil is easier to work with than no oil at all, which is why the future for reduced- fat dressings, is so promising. Consumers seem to have come to learn that it is all about moderation. And if the small level of oil used in such dressings improves flavor and mouth-feel, as well as avoids the undesirable translucent appearance of no oil systems, you’ve got a winner. Consumers have become accustomed to certain dressing viscosities that provide body and cling and they won’t settle for anything else.”

When removing and replacing oil, the formula and/or the process must be adjusted in order to manufacture a product that satisfies consumers’ expectations. Those expectations vary based on the category of dressing, spoonable or pourable.

Spoonable dressings tend to have a glossy appearance and creamy but firm texture. Manufacture typically involves a high-heat cook step followed by high shear. “They evolved from classic mayonnaise and exhibit a similar consistency,” says Judy Turner, research and development specialist, Tate & Lyle, Decatur, IL. “Although viscous with a slight set or gelled texture, a small amount of shear, such as spreading with a knife, results in a spreadable, creamy product.”

Pourable dressings, on the other hand, are quite varied and exhibit a wide range of texture, viscosity and sweetness. A smooth texture with a clean, short break is highly desired. Pourable dressings are most often cold processed and undergo high shear to complete the emulsion.

“Pourable dressings tend to have a thinner, more flowable structure,” says Turner. “Proper viscosity development is integral to success in either system. This is where starches can play a lead role. Starches not only provide viscosity and stability in spoonable and pourable formulations, but also texture that contributes to mouth-feel and flavor. Although spoonable and pourable dressings can be made with either cook-up or instant starches, spoonables typically incorporate cook-up starches, while pourable formulators prefer the instant varieties.”

But it’s not just a matter of removing oil and adding starch. Sullivan adds, “When the fat or oil content is reduced in a dressing product, the revised or altered application development requires a total reformulation approach. Some adjustment must be made in the usage level of almost every ingredient in the new formula.

“The levels of starch and hydrocolloid increase as the oil content is reduced,” says Sullivan. “It then becomes important to balance the formulation and not create undesirable gelling and mouth-feel. Using an unmodified starch may seem economically attractive, but higher levels could cause the dressing to retrograde, resulting in syneresis or pulling away from the sides of the container. Some starches and gums also can continue to hydrate on the shelf, increasing the viscosity of the product.”

In addition to starches and hydrocolloids, dressing designers will often use maltodextrins and/or corn syrup solids to help bulk up the reduced- fat dressing system. “These non sweet ingredients provide body, viscosity and lubricity to low-fat formulations,” says Sullivan. “They act as a carrier and are compatible with other ingredients. Both contribute to a smooth mouth-feel with low flavor impact and excellent sheen. They will also aid in developing the opacity needed when oil is removed.”

More texturizing tricks 

To aid product formulators, some suppliers now offer an optimized group of ingredients to meet reformulation needs, such as lower calories, reduced fat or cold processing. One such product from Tate & Lyle, for example, includes modified food starch, gums, sucralose and maltodextrin, and was designed for pourable creamy-style dressings, such as buttermilk ranch. According to Turner, combining the premix with oil creates a slurry that can be added during the aqueous phase and mixed until smooth. “Dressings and sauces made with this product can withstand normal processing and finishing equipment such as a colloid mill, homogenizer or a heat-processing pasteurization step,” she says.

“Traditionally, the ingredient most commonly used in the emulsification of oil and water and vinegar-based salad dressings has been egg yolk, which also contributes to the flavor, mouth-feel and fat content of the end product,” says Turner. “But when you’re reducing fat, egg yolk is an obvious emulsifier to replace with one that is nonfat.”

Photo: FMC BioPolymer

Varying the level and type of cellulose gel can help simulate fat and improve the mouthfeel of reduced-fat salad dressings.

Sheldrake adds, “Emulsified oilin- water dressings are made using a high-shear process, where the energy that is imparted changes the state of the ingredients from their most thermodynamically stable state into a kinetically stable but higher energy state emulsion. Egg yolks can handle this shear. Not all starches can.

“Native starches are typically very shear-sensitive, and thus applying shear causes them to break down. Modified starches have less of a tendency to break, and thus they can cope with the process and stabilize the mix,” says Sheldrake. “Most of the starches that are made this way have a tolerance level, and it is well known that some are better than others.”

Suppliers are also turning to advanced breeding techniques to develop options to traditional starches. For example, Avebe’s new Eliane™, a GMO-free waxy potato starch, contains more than 99% amylopectin, combining the functionality of potato starch with a short, shiny texture. “This new amylopectin potato starch exhibits the very high viscosity of regular potato starch without the salt sensitivity,” says Sheldrake. Unlike some other ingredients used to replace oil, this new waxy potato starch produces a clear solution. “Regular potato starch contains about 20% amylose, which can increase solution opacity due to the retrogradation that comes with amylose content,” he explains. “This new potato starch provides dressing designers with the benefits of traditional potato starch, such as high viscosity and a clean, neutral flavor, along with the benefits of a waxy maize starch, which includes producing clear solutions.”

Clarity and suspension stability are important consumer drivers in the clear-dressing market. “Compared to other starches, the low-fat and protein content of potato-based starches means that higher levels of clarity are achieved,” says Sheldrake. This results in a clean eating experience and a glossy finish—all without flavor masking.

In addition to formulating dressings with starches for their thickening, stabilizing and even clarity properties, specialty lipophilic starches can assist with emulsification.

“While starch is a preferred way to provide viscosity and gelling properties to water-based formulations, it has no compatibility with oil. However, when the starch molecule is chemically modified by the addition of lipophilic substituent groups (octenyl succinic anhydride, or OS), it yields a starch with both lipophilic and hydrophilic characteristics capable of emulsification,” says Turner. “For example, cook-up lipophilic starches can be cooked along with the existing starch paste, or cooked in a separate paste and combined.” She notes both methods will reduce the amount of thickening starch required in the formula.

“Cold-water-swelling lipophilic starches are added after the cook, as when using traditional egg yolk,” says Turner. “In a spoonable salad dressing, the starch is slurried in oil and then added to the cooled paste, followed by the addition of the remaining oil. In a pourable salad dressing, the starch is also slurried in oil and added to the dressing before the bulk of the oil is added.”

The hydrophilic backbone of the lipophilic starch interacts with the aqueous, or continuous, phase of the emulsion, while the OS group interacts with oil droplets in the dispersed phase. The modified lipophilic starch adsorbs at the oil/water interface and orients itself with the OS group, interacting with the oil droplets and the hydrophilic starch backbone in the aqueous phase. In addition, since the starch has many OS groups randomly attached to it, it creates a hydrophilic starch film around the oil droplet. This film provides a barrier, which prevents the individual oil droplets from coalescing and results in steric stabilization of the emulsion.

“A good formulation starting point is to use 0.5% to 1.0% lipophilic starch for every 10% oil to be emulsified,” says Turner. “These starches can be used alone or blended to achieve the desired viscosity and texture.”

As mentioned, hydrocolloids are sometimes used with starch to simulate the removed oil in reduced-fat dressings. They may also be used in their own unique combinations. For example, “cellulose gel is capable of creating a colloidal dispersion that structures water and thereby simulates the rheological properties of fat,” says Janet van Mol, senior research scientist, FMC BioPolymer, Princeton, NJ. “Varying the level of cellulose gel and the type of cellulose gel allows formulators to develop dressings with the desired texture, mouth-feel and degree of cling. It also adds opacity, which is critical in water-based dressings that are meant to be creamy-style.”

Cellulose gel is made from naturally occurring alpha cellulose, such as that found in trees, fruits and vegetables. During processing, the fibrous material contained in the alpha cellulose is hydrolyzed, leaving bundles of microcrystals. These microcrystals are co-processed with other ingredients, such as sodium carboxymethlycellulose (CMC), maltodextrin, xanthan gum or sweet dairy whey, to produce colloidal cellulose gel. “When dispersed in water, the cellulose gel is activated by shear, and the particles form a three-dimensional network that acts as a physical matrix. This allows for emulsion stability and creamy mouth-feel,” says van Mol. Cellulose gel is an emulsion stabilizer that forms thixotropic gels. It does not reduce the surface tension, but does have an affinity for both water and oil. Cellulose gel will locate at the interface surrounding the oil globules and thereby prevent oil separation.

“Within dressing applications, a protective colloid, such as xanthan gum or CMC, is recommended to prevent flocculation of the Avicel® cellulose gel due to low pH (below 4.0) and high salt content (greater than 1.5%) typical of dressing formulations,” says van Mol.

“Co-processing the cellulose microcrystals with an ingredient such as pectin or alginate provides enhanced properties to food systems. For example, cellulose gel co-processed with pectin provides greater stability in low-pH systems, thereby eliminating the need for a protective colloid to prevent flocculation. Co-processing cellulose gel with alginate allows for functionality within dry mix applications,” says van Mol. Typical usage levels for cellulose gel in dressing applications is in the 1% to 2% range, depending upon the formulation and desired viscosity of the end product.

Photo: Birds Eye Food, Inc.

Some hydrocolloid ingredients can increase viscosity and help enhance cling in reduced-oil salad dressings to maximize the visual impact of particulates, like herbs.

“If a full-bodied, extra-creamy dressing is desired, a formulator may choose to use Novagel® cellulose gel,” says van Mol. “Here, the cellulose microcrystals are coprocessed with guar gum to produce a particle shape that mimics that of oil globules, hence producing a fatlike mouth-feel.” When dispersed in water, this gum mimics the rheological properties of fat, including slip and mouth-feel, she notes.

When working with any of these cellulose gel ingredients, dressing manufacturing starts with dispersing the cellulose gel in water with shear to form an insoluble three- dimensional network of cellulose microcrystals. “The order of addition in preparation of dressings is critical,” says van Mol. “If another hydrocolloid, such as xanthan gum, is utilized, it must be added to the cellulose gel dispersion prior to the addition of the remaining dry ingredients. This ensures even and complete hydration, allowing the soluble hydrocolloid to prevent the cellulose gel from flocculation.”

When using any of these ingredient systems to reduce the oil level in dressings, it is important for the designer to consider dispersion times, hydration rates, ingredient interactions and incorporation into the system. “Ingredient selection must be matched to the process equipment,” concludes Sullivan. “With improper mixing or dispersion, some ingredients such as cold-water-swelling instant starches and gums can cause undesirable fish-eyes and lumps that are not easily removed. Additional shear or mix tanks may be required for development of a quality product.”