Painting Better Greens

Painting Better Greens

By Donna Berry 
Contributing Editor

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 isthat rather than washing off, it peels off, much like dried latex paint on a nonporous surface. This should be no surprise, as fat-free creamy dressings andlatex paint both consist of polymers suspended in water.

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

Its the oil, says Paul Tutt, director, Enova brand for ADM KaoLLC, Decatur, IL. Fat provides a lubricity and mouth-feel that is unmatched byany fat substitute. This is one of the reasons why fat-free dressings havestruggled to achieve broad consumer acceptance, and the lighter or reduced-oildressings are becoming more common.

The name game 

Before you start removing oil in dressing, it isimportant to be aware that the term salad dressing has a standard ofidentity. The Code of Federal Regulations (CFR) states that products labeled saladdressing (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 itto contain 35% vegetable oil. Thus, to be compliant, manufacturers must becareful to properly use the familiar term salad dressing on productlabels. 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 regularformulation. Again, if the standardized term salad dressing is used, rather thansimply dressing, the product must also contain 4% egg yolk. The same holdstrue for these other legal descriptors.

Low-fat dressings must contain no more than 3 grams of fat perreference amount, says Celeste Sullivan, senior applications scientist, GrainProcessing Corp. (GPC), Muscatine, IA. The established reference amounts are15 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 thereference food on the label and state the percent or fraction by which the fathas been reduced from the regular product, says Sullivan. If the standarddressing derives more than 50% of its calories from fat (as in most saladdressings), the light product must contain at least 50% less than the regularproduct. The regular or reference food must be representative of the typeof food bearing the light claim. Also, the nutrient value of the referencedressing must be representative of a broad spectrum of foods of that type. Theregulations specify how the nutrient values (fat and calories) for the referencefood 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 andstill producing a palatable dressing that clings onto salad greens is the next.

Paul Sheldrake, market managerliquid systems, Avebe u.a., Veendam, theNetherlands, adds, One of the greatest innovations in the traditional mayonnaise and dressingmarket is clearly the introduction of starch-based stabilizers that allow forlower-oil-content products.

Texture is one of the most important consumer features of dressings, saysSheldrake. A traditional full-fat dressing has a short cuttable andspoonable texture that arises from the packing effect of the emulsified oildroplets. The food technologist needs to bear this in mind when developing alower-fat alternative. Potato- or maize-based starches, for example, are a goodchoice as they tend to give a shorter texture, while those from tapioca tend tobe longer.

According to ACNielsen Label- Trends, some oil definitely helps, and whenit 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, whilefat-free dressings sales decreased 2.4% to $20.4 million.

Oils well 

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, alongwith a rich, premium eating quality, says Sullivan. Lubricity andcreaminess 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 thatjust is not possible when no fat is in the formula, Tutt adds. Forexample, Enova brand oil is the first salad oil clinically shown to helpconsumers maintain a healthy weight and lifestyle when used as part of asensible diet. When you metabolize the fat in Enova oil, much of the fat is sentto the liver where it participates in betaoxidation pathways and is used morereadily than stored fat.

Enova oil is manufactured through a process that starts with soy and canolaoils, so the product has a light, neutral taste that doesnt mask the flavorsof other ingredients. The component that makes it stand out from other oilsdiacylglycerols(DAGs)is initially present only in small quantities. Through a patentedprocess, ADM Kao LLC, a joint venture between ADM and Kao Corporation, Tokyo,converts the predominant triacylglycerols (TAGs) in natural soy and canola oilsinto a mixture that is at least 80% DAGs. TAGs carry three fatty acids on a backbone molecule; DAGs carry only twofatty 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 wayand absorbs the resulting fatty acids into the intestine, says Tutt. Thenthe intestine rebuilds the fatty acids into fat molecules and combines them intopackets called chylomicrons that are sent to the bloodstream, to be stored inbody tissues. Due to the shape of the 1,3-DAG molecules, enzymes in theintestine cannot efficiently recombine the pieces of this fat into fatmolecules, 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 isvirtually indistinguishable from conventional oils in final productapplications. It is listed in ingredient statements as diacylglycerol oil.It is cholesterol free and an excellent source of vitamin E. It also has onlyabout 4% saturated fat and zero grams of trans fat per serving. The next best conventional oils are derived from safflower, sunflower andcanola, and range in saturated fat content from 6% to 8%. The omega-6 to omega-3ratio in Enova oil is 10-to-1. Being an oil, it has 120 calories per 1tablespoon serving, the same as other conventional oils. It is not a low-calorieoil; its point of differentiation is that, because it is metabolized differentlythan conventional oils, less oil is stored in the body as fat compared to othercooking 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 buildback 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, whichis 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 oilsystems, youve got a winner. Consumers have become accustomed to certain dressing viscosities that providebody and cling and they wont settle for anything else.

Cling comes thick or thin 

When removing and replacing oil, theformula and/or the process must be adjusted in order to manufacture a productthat satisfies consumers expectations. Those expectations vary based on the category of dressing, spoonable orpourable.

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

Pourable dressings, on the other hand, are quite varied and exhibit a widerange of texture, viscosity and sweetness. A smooth texture with a clean, shortbreak is highly desired. Pourable dressings are most often cold processed and undergo high shear tocomplete the emulsion.

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

But its not just a matter of removing oil and adding starch. Sullivanadds, When the fat or oil content is reduced in a dressing product, therevised or altered application development requires a total reformulationapproach. Some adjustment must be made in the usage level of almost everyingredient in the new formula.

The levels of starch and hydrocolloid increase as the oil content isreduced, says Sullivan. It then becomes important to balance the formulation andnot create undesirable gelling and mouth-feel. Using an unmodified starch mayseem economically attractive, but higher levels could cause the dressing toretrograde, resulting in syneresis or pulling away from the sides of thecontainer. 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 usemaltodextrins and/or corn syrup solids to help bulk up the reduced- fat dressingsystem. These non sweet ingredients provide body, viscosity and lubricity tolow-fat formulations, says Sullivan. They act as a carrier and are compatible with otheringredients. Both contribute to a smooth mouth-feel with low flavor impact andexcellent sheen. They will also aid in developing the opacity needed when oil isremoved.

More texturizing tricks 

To aid product formulators, some suppliersnow offer an optimized group of ingredients to meet reformulation needs, such aslower calories, reduced fat or cold processing. One such product from Tate & Lyle, for example, includes modified foodstarch, gums, sucralose and maltodextrin, and was designed for pourablecreamy-style dressings, such as buttermilk ranch. According to Turner, combiningthe premix with oil creates a slurry that can be added during the aqueous phaseand mixed until smooth. Dressings and sauces made with this product canwithstand 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 ofoil and water and vinegar-based salad dressings has been egg yolk, which alsocontributes to the flavor, mouth-feel and fat content of the end product, saysTurner. But when youre reducing fat, egg yolk is an obvious emulsifier toreplace with one that is nonfat.

Sheldrake adds, Emulsified oilin- water dressings are made using ahigh-shear process, where the energy that is imparted changes the state of theingredients from their most thermodynamically stable state into a kineticallystable but higher energy state emulsion. Egg yolks can handle this shear. Notall starches can.

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

Suppliers are also turning to advanced breeding techniques to develop optionsto traditional starches. For example, Avebes new Eliane, a GMO-free waxy potato starch, containsmore than 99% amylopectin, combining the functionality of potato starch with ashort, shiny texture. This new amylopectin potato starch exhibits the veryhigh viscosity of regular potato starch without the salt sensitivity, saysSheldrake. Unlike some other ingredients used to replace oil, this new waxypotato starch produces a clear solution. Regular potato starch contains about20% amylose, which can increase solution opacity due to the retrogradation thatcomes with amylose content, he explains. This new potato starch providesdressing designers with the benefits of traditional potato starch, such as highviscosity and a clean, neutral flavor, along with the benefits of a waxy maizestarch, which includes producing clear solutions.

Clarity and suspension stability are important consumer drivers in theclear-dressing market. Compared to other starches, the low-fat and proteincontent of potato-based starches means that higher levels of clarity areachieved, says Sheldrake. This results in a clean eating experience and aglossy finishall without flavor masking.

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

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

Cold-water-swelling lipophilic starches are added after the cook, as whenusing traditional egg yolk, says Turner. In a spoonable salad dressing, the starch is slurried in oiland then added to the cooled paste, followed by the addition of the remaining oil. In a pourable salad dressing, the starch is also slurried inoil 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 oildroplets in the dispersed phase. The modified lipophilic starch adsorbs at theoil/water interface and orients itself with the OS group, interacting with theoil droplets and the hydrophilic starch backbone in the aqueous phase. Inaddition, since the starch has many OS groups randomly attached to it, itcreates a hydrophilic starch film around the oil droplet. This film provides a barrier, which prevents the individual oil droplets fromcoalescing and results in steric stabilization of the emulsion.

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

Simulating fat 

As mentioned, hydrocolloids are sometimes used withstarch to simulate the removed oil in reduced-fat dressings. They may also beused in their own unique combinations. For example, cellulose gel is capableof creating a colloidal dispersion that structures water and thereby simulatesthe rheological properties of fat, says Janet van Mol, senior researchscientist, FMC BioPolymer, Princeton, NJ. Varying the level of cellulose gel and the type of cellulose gel allowsformulators to develop dressings with the desired texture, mouth-feel and degreeof cling. It also adds opacity, which is critical in water-based dressings thatare meant to be creamy-style.

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

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

Co-processing the cellulose microcrystals with an ingredient such aspectin or alginate provides enhanced properties to food systems. For example,cellulose gel co-processed with pectin provides greater stability in low-pHsystems, thereby eliminating the need for a protective colloid to preventflocculation. Co-processing cellulose gel with alginate allows for functionalitywithin dry mix applications, says van Mol. Typical usage levels for cellulose gel in dressing applicationsis in the 1% to 2% range, depending upon the formulation and desired viscosityof the end product.

If a full-bodied, extra-creamy dressing is desired, a formulator maychoose to use Novagel® cellulose gel, says van Mol. Here, the cellulosemicrocrystals are coprocessed with guar gum to produce a particle shape thatmimics that of oil globules, hence producing a fatlike mouth-feel. Whendispersed in water, this gum mimics the rheological properties of fat, includingslip and mouth-feel, she notes.

When working with any of these cellulose gel ingredients, dressingmanufacturing starts with dispersing the cellulose gel in water with shear toform an insoluble three- dimensional network of cellulose microcrystals. The order of addition in preparation of dressings is critical, says vanMol. If another hydrocolloid, such as xanthan gum, is utilized, it must beadded to the cellulose gel dispersion prior to the addition of the remaining dryingredients. This ensures even and complete hydration, allowing the soluble hydrocolloidto prevent the cellulose gel from flocculation.

When using any of these ingredient systems to reduce the oil level indressings, 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 ingredientssuch as cold-water-swelling instant starches and gums can cause undesirablefish-eyes and lumps that are not easily removed. Additional shear or mix tanks may be required for development of a qualityproduct.

Donna Berry, president of Chicago-based Dairy & Food Communications,Inc., a network of professionals in business-to-business technical and tradecommunications, has been writing about product development and marketing for 11years. Prior to that, she worked for Kraft Foods in the natural-cheese division.She has a B.S. in Food Science from the University of Illinois inUrbana-Champaign. She can be reached at [email protected].