Dressing Up

 Dressing Up
July 1997 -- Design Elements

By: Robert J. Bannar
Contributing Editor

  Americans love "healthy" foods, especially salads, piling their plates high with lettuce, tomatoes and other garden goodies. During the past, in typical Yankee fashion, they would smother that healthfulness with a rich, thick, creamy salad dressing - loaded with fat, calories and cholesterol. And who could blame them? The only alternatives were either settling for watery, tasteless dressings or dummying-down their calorie counts.  But times change. Food processors now are learning how to give consumers what they want: guilt-free flavor and pleasant mouthfeel, with salad dressings no exception. Today's "lighter" products move closer to the "real thing" all the time. That's one reason why low-oil and no-oil salad dressings appeal to more than the weight-conscious crowd these days. That - and a steady barrage of bad news about the ill effects of fat, calories and cholesterol - has more consumers going beyond reading the brand name and flavor to examining the ingredients and nutritional data.  Supermarket sales of pourable salad dressings totaled about $1.1 billion in 1994, up 6% over 1993, according to the Association for Dressings & Sauces, Atlanta. Low-oil and no-oil products already account for about one-third of that market.Designing a dressing  Building a salad dressing sounds simple. Start with oil and vinegar and sprinkle in a spice or two. Then shake and serve immediately. But what about shelf life? That complicates matters. Add an emulsifier to prevent product separation, and adjust the pH to prevent spoilage. Then toss in some gums to help stabilize that emulsion. Also needed are flavors, herbs and spices capable of withstanding processing, yet maintaining the same flavor profile over long-term storage. Most important, all these parts must work together like a well-tuned engine.  Simple oil and vinegar makes a good salad dressing, but not just any oil and vinegar. Choosing these two components constitutes the prime step. Blended according to taste, cost and availability, they range from the most upscale combination - olive oil and balsamic vinegar - to the more common and less costly cottonseed oil and 200-grain vinegar.  The right blend for a particular application represents a compromise, determined by such factors as type and size of process, marketing strategy and other considerations. For example, some oils require antioxidants, thereby preventing using an "all-natural" label.  Smaller "specialty" processors might opt for higher cost ingredients because they're getting a better price for the product, and are buying those expensive ingredients in smaller quantities. Also, the gourmet label "protects" the price.  Large-volume, mainstream processors view it differently; they've got the same quality goals but must buy larger quantities, affecting their initial capital investment and creating storage and handling concerns. They face a fickle marketplace as well as changing marketplace factors, such as sales and couponing, which regulate the price and profit margin.Spirit of oil  Every salad dressing starts with oil - even in fat-free (no-oil) dressings, oil is present "in spirit." Why? Because oil provides the standards by which most salad dressings are judged - the expected functional and organoleptic properties, such as flavor and mouthfeel, the "cling" to the salad components. Oil is the vehicle upon which flavors travel. And, of course, oil also adds most of the fat and calories.  Oils used for salads derive mainly from vegetable sources. Primary varieties include olive, soybean, canola and sesame. Salad oils are typically refined, bleached and deodorized. Product designers may use a lightly hydrogenated version to reduce the level of unsaturated fatty acids for extra oxidative stability. However, normal low temperature storage and usage conditions don't promote rancidity, making hydrogenation the exception, rather than the rule.  Oils with a high level of saturated fats (the level can be increased by hydrogenation) tend to crystallize under refrigeration; in addition to looking unappetizing, this also breaks the emulsion, so they are not often used in salad dressings. The higher melting-point solids can be removed by winterization, a type of fractionation using cool temperatures and filtration. Oils also may be clarified through dewaxing.  Some dressings require a specific oil level to meet federal standards of identity for that product. Mayonnaise must contain not less than 65% vegetable oil, and spreadable salad dressings not less than 35%. In the pourable category, French requires at least 35% vegetable oil. A product labeled "reduced calorie" must contain at least one-third fewer calories than a full-fat dressing.  The type of oil selected for a salad dressing depends on several considerations:cost and availability;flavor;health and labeling;stability to oxidation; melting point.  Soybean oil is perhaps the most popular of the vegetable oils these days. It can be used effectively in regular, and reduced- and low-fat dressings. It offers clean, natural flavor and good shelf life. Like all vegetable oils, it's cholesterol-free. And, it's readily available in this country and competitively priced.  Canola oil also is used in some formulations for its lower amounts of saturated fats. It's used in the United States in "special products," especially for "nutritional" labeling/marketing reasons. In Canada, however, it is often the "oil of choice," over soy.  For many kinds of dressings, olive oil might prove the leader in taste, quality and in cost. But an Italian dressing, for example, doesn't require 100% olive oil to be acceptable. But it should contain some olive oil for taste, color and texture, and labeling. A 50:50 ratio of olive to soy can balance cost and flavor.  Sesame oil certainly represents the choice for Oriental-flavored salad dressings. Because it is a highly flavorful oil, however, sometimes just a little is added for flavor. Using it at 100% generally constitutes "overkill" for cost and taste.  Oil quality is absolutely essential for a quality product. Look for a bland-tasting oil (except those used as a flavoring oil). It should possess a clean flavor, with no "off notes," such as a beany, painty taste, or simply too strong a flavor. Oils should have a low peroxide value and show no signs of oxidative rancidity. Otherwise, the finished product will suffer from poor quality and insufficient shelf life.  A higher level of saturated fat increases resistance to oxidation. Adding saturated fat might prove necessary if the product is exposed to pro-oxidants: low levels of heavy-metal ions; light; and even chlorophyll-containing ingredients, such as parsley flakes. Citric acid or other chelates can provide some antioxidant benefits by inactivating the metal ions.  Occasionally, such antioxidants as BHA and BHT are added to retard rancidity, but these might be unwelcome in some formulations, especially those marketed to upscale and health-oriented markets. Tocopherols and other natural antioxidants, such as rosemary extracts, may also extend the shelf life while providing more label-friendly alternatives. However, depending on the application, formulation and level used, these might not prove as effective as synthetic versions.  Selecting the right oil (or oils) demands careful consideration; once a particular oil, or blend of oils, has been chosen, it's difficult to change it, because of the consumer's flavor perceptions of the product.Success without oil  Today's market demands "no-oil" salad dressings. So, the real question is: Can an acceptable salad dressing be made without oil? The answer is "yes." And it's been successfully done. What cannot be done, at least from a consumer acceptance standpoint, is making a salad dressing without the properties or characteristics of oil.  A full-oil dressing is inherently viscous, and removing the oil reduces the viscosity, as well as calories and cholesterol. So, the first step in creating a no-oil dressing is to restore that viscosity. This can be done with starches, gums and other ingredients.  Due to their opacity and sweetness modification, maltodextrins and corn syrup solids have been used for fat and solids replacement. Maltodextrins also provide or improve solubility, and help standardize viscosity from gums and hydrocolloids.  In salad dressings, maltodextrins also help provide body and cling, and help decrease the stringiness many gums promote. In fat-reduced salad dressings, they offer solids with low sweetness. By building body and lubricity, they augment gums and starches.  Maltodextrins and corn syrup solids serve as effective carriers for sweeteners, gums, spices and seasonings. They also are good carriers in dry mixes, where they allow the addition of moisture- or oil-containing ingredients; deliver effective bulking; and promote instant solubility.  Grain Processing Corp., Muscatine, IA, for example, developed a trial formulation that uses maltodextrin as a partial fat replacer in a creamy Italian low-calorie salad dressing (with just 1.5 calories per gram). It builds solids, mouthfeel and eating quality without adding sweetness - objectives often compromised when oil content is lowered.  Modified food starches also contribute solids for viscosity. Food starches provide partial oil replacement, build solids and acids, and provide added heat- and shear-stability. They also are a good choice for use in dry-mix dressings, such as "ranch flavor," to allow the mix to be prepared with less oil or mayonnaise, says Bill Mason, research associate, National Starch and Chemical Co., Bridgewater, NJ.  Modified whey protein can add viscosity and mouthfeel as well as provide other benefits. While generally added to create the opacity required in such products as a creamy Italian or ranch dressings, modified whey proteins also can help round out the harsh flavor of vinegar in low-oil or no-oil dressings, making them taste less tart and biting, says Martin Davis, general manager, Davisco International, Inc., LeSueur, MN.  Other ingredients, too, help mimic fat's mouthfeel - such as microcrystalline cellulose (MCC). Although MCC can be used alone for this purpose, it is often blended, or preblended, with other gums and stabilizers into "systems" primarily intended to provide viscosity and suspension. Such a blend might include a gum (such as acacia) as an emulsifier and lubricant; a hydrocolloid (alginate, carrageenan, carboxymethylcellulose, MCC, xanthan, or a guar-locust bean-pectin blend) as a thickener and gel former; an opacifier (NFDM, soy protein or starch) to simulate fat opacity; and soluble solids (high fructose corn syrup, corn or rice syrup, maltodextrins or polyols) to reduce water activity and add bulk.  Before eliminating all the oil, however, consider a bit of advice suggested by Florian Ward, Ph.D., vice president of research and development for TIC Gums, Inc., Belcamp, MD: "Even no-oil dressings should have a little oil, perhaps 2% to 3%, for the organoleptic qualities - just enough to keep it under the 0.5 gram-per-serving limit to qualify for a no-fat label."The acidifier test  Acidification constitutes an important component in a salad dressing. It provides necessary tartness as well as microbialial stability by lowering the pH.  Vinegar is the most common acidifier in dressings, with many available choices. White-wine, red-wine and cider vinegars represent the most common varieties. Balsamic vinegar, currently a gourmet favorite, is expensive and highly flavored. Rice-wine vinegar is noted for its milder flavor.  Vinegar strength is measured in grains. This refers to the percent acid, times 10. (A 200-grain vinegar is 20% acetic acid).  The vinegar, or vinegar blends, chosen must work across a full spectrum of products. In fact, Tricia Laning, product development food technologist at Burns Philp Food Ingredients, Des Moines, IA, points out that some companies simply buy a 200-grain white distilled vinegar, then dilute it (with water) to the desired strength or strengths needed, typically to about 120-grain.  Lemon (and sometimes lime) juice also is used as an acidifier - sometimes in combination with vinegar. Lemon juice is a good flavor potentiator, and helps balance out other flavors  Because vinegar and juices supply flavor, as well as pH reductions, it might be necessary to use additional acidulants in the formulation to achieve the required pH, without compromising the taste. For salad dressings, the main acidulants for this purpose include citric and lactic, although others could be used if they produce the desired effect.  These acids provide slightly different acid-taste delivery. Citric has a quick, sharp bite suited for a fruit or vegetable flavor profile. Lactic tends to be milder, with a lingering taste, and is especially suited for creamy or dairy-based dressings. Additional details can be found in "Acid Basics: The Use and Function of Food Acidulants" (May 1993 Food Product Design).  One of the pitfalls in reducing or removing oil from a salad dressing is that it also reduces the total solids, which often affects acidity. Acidity also changes when water levels are increased. The common tendency, most experts point out, is to achieve the desired acidity by increasing the amount of vinegar. However, in the reduced-fat or reduced-calorie arena, balancing the acidity of the vinegar and the sweetener, without exceeding the desired calorie-per-gram limit, creates an even greater challenge. Moreover, adding more vinegar increases "harsh" flavor notes.Oil and water  Oil and water don't mix - naturally. An emulsion, consisting of dispersed droplets in a matrix, can be formed to create a consistent product. Over time, the droplets coalesce and oil floats to the top. This might prove acceptable for an oil-and-vinegar-style dressing, but would make an unappealing ranch variety. This points to the need for an emulsifier, an ingredient which encourages these two immiscible liquids to remain evenly dispersed without separating. Emulsifiers also promote wetting and dispersability in dry mixes, and improve body and texture, particularly in lower-fat products.  Emulsifiers contain hydrophilic (affinity for water) and lipophilic (affinity for fat) portions that serve as the basis for their functionality. They orient themselves at the interface of the droplet and the continuous phase, holding them together. The affinity for the water and fat of a particular emulsifier is indicated by the hydrophilic/lipophilic balance (HLB) - the higher the HLB, the greater the emulsifier's affinity for water. While not true in every case, in general, when oil is in the continuous phase, a low HLB emulsifier should be used; and the higher the oil level, the lower the HLB. A dressing with water as the continuous phase requires a higher HLB number, and as the water percentage rises, so should the HLB.  Typical emulsifiers used for dressings include polysorbates (60 and 80), lecithin and egg yolks. The choice depends on such factors as cost, availability, synergy with other ingredients, labeling concerns, and so on. The polysorbates are difficult to disperse because they're oil-soluble. Low-fat dressings typically rely on oil-in-water emulsions; monoglycerides and soy lecithin are commonly used here. Using an emulsifier in lower-fat dressings creates smaller fat droplets, which extend the fat's functionality, particularly in terms of mouthfeel and texture.  In reduced-oil dressings, egg yolks help generate smooth mouthfeel. They're not generally used in no-fat dressings, however, because they add fat calories to the product. In mayonnaise-based spoonable dressings, where egg yolks often are used as the emulsifier, modified whey can replace the egg yolks and maintain an emulsion in the dressings.  Whey protein concentrates also can be excellent emulsifiers, and can replace eggs in nonstandard salad dressings. They form a thicker product than eggs, however. In nonstandard dressings - such as Thousand Island or blue cheese - 100% of the egg solids can be successfully replaced with whey protein concentrates, although the blue cheese might require added cheese flavor.  Although emulsifiers help create and stablize emulsions, they may require some help to achieve the six-to-eight-month shelf life requirements of most dressings. So, stabilizer systems will be required to stabilize the emulsion.Clingy  Perhaps the age-old question is: How do you get a salad dressing to flow smoothly and easily out of the bottle, yet still cling to the salad ingredients? The answer, explains Allan Freed, president, Gum Technology Corporation, Tucson, AZ, is to recognize that "cling" is not directly related to viscosity alone, but to other physical properties of the system, such as stabilization.  "It depends on the types of stabilizers (typically, gums and hydrocolloids) you select," Freed says." While xanthan gum is a common choice for this purpose, there are other gums and hydrocolloids - usually in blends with xanthan - that may work better to provide more cling." One of the company's products, which combines xanthan, guar and alginates, is able to "provide consistent, smooth viscosity with more cling than xanthan alone," he says.  Gums and starches stabilize emulsions by two means. First, an increase in viscosity slows the coalesence of the emulsion droplets. Second, many hydrocolloid stabilizers form a physical network that holds droplets in place.  Some gums possess emulsion-forming properties; this should be taken into consideration in developing a formulation. Among these are gum tragacanth; gum acacia (a natural emulsifier); and propylene glycol alginate (a good emulsifier, but not natural). They also suspend spices and particulates, primarily by increasing solution density.  Stabilizer systems also are used in full-fat dressings to improve, enhance or control the rheology. A dressing can be thickened due to an increase in solids or the formation of a gel network. Or it can be "engineered" to promote pourability, without sacrificing cling, by using unique viscosity characteristics, such as shear-thinning. (Product viscosity decreases when shear - through shaking and pouring - is applied.)  Some stabilizers, especially gums, are expensive on a per-pound basis, but small amounts are actually used so that cost is not generally a concern. In fact, using too much harms products. Use most gums at more than 0.75% (by weight) and the result will be "salad glue," rather than dressing. Excess starch produces pastiness.  Working with stabilizers can prove tricky. It can be difficult to disperse gums without creating lumps, because they hydrate too rapidly. The traditional method has been to disperse the stabilizers in other dry ingredients, such as salt or sugar, then make a slurry, typically using high shear. Today, however, prehydrated gums are available, which are especially helpful in creating no-fat dressings. They disperse easily, with little shear. And although they may be a little more expensive initially, they compensate for the added cost down the line by saving time, and avoiding problems.  Stabilizers often can affect flavor perception, too. Xanthan, for example, can "delay" flavor release, which could prove a good thing for a no-oil product, but perhaps not so great for a full-oil or reduced-oil product, since oil can create the same effect.  Two ingredients common to salad dressing - salt and vinegar - can form hydrogen bonds with gums, thereby delaying the hydration rate of the gums. If the acetic acid content of the vinegar is high, prolonged heating, combined with low pH, might delay viscosity due to hydrolysis of the gums. Initial viscosity can be increased, without affecting pH, in two ways: hold back some of the vinegar until the after the gum is hydrated; or, if other acidulants also are used, add those acidulants after gum hydration, permitting a higher water-lower vinegar ratio. Immediate viscosities of dressings made with vinegar added before the gum have been found to be as much as 10% lower than for those in which the gum was added before the vinegar.  Spoonable dressings generally are more viscous because they contain a higher oil content, but they may need more stabilization to protect or preserve that viscosity. A low-calorie spoonable dressing can be developed using cellulose powder as a non-nutritive thickener. Milling is necessary to smooth the texture (reduce the particle size of the cellulose powder) and to disperse the oil.  Low-cal spoonables also have been developed using starch and propylene glycol alginates as thickeners, with egg products as emulsifiers. Their oil content is in the 5%-to-12% range (8% is preferable), and they also require glycerol (1% to 2%) for sheen and mouthfeel.  In dry mixes, hydrocolloids provide texture, emulsion stability and appearance. One important factor is that they need to be easily dispersed and hydrated. The viscosity also should not change significantly if stored.  Again, it's not desirable to stock a different stabilizer system for every product. Xanthan seems to be the do-all gum for salad dressings, but no single gum works "across the board."  Stabilizing systems aren't always transferable from one product to another. A system providing emulsion stabilization, thickening and suspension in a spoonable dressing, for example, might not work in a pourable dressing, because it might form a rigid gel, undesirable in the pourable dressing.Oldies but goodies  Choosing the right flavor, or flavors, is paramount to a salad-dressing assortment.  The first stop is usually the marketing department: Do they want to offer a line of standard salad-dressing flavors? Do they desire a new, creative line? Do they want to add new twists to old favorites? Or do they hope to mix these strategies?  Several salad-dressing flavors are kitchen pantry favorites: Italian, French, Russian, Thousand Island and blue cheese, to name a few. But it doesn't take long for a new flavor to catch on and attain standard status (Catalina, ranch, honey/dijon mustard) or to suffer a fall from grace (whatever happened to Green Goddess? Roquefort? Louis?).  The second step is locating flavors, or flavor systems, that not only satisfy a company's marketing strategies, but that work with the other ingredients in formulations, and with processing and packaging systems.  No-oil dressings create new and different flavor challenges. Some flavors used in a 35% oil product can be perceived as being as much as 1,000 times stronger when used in a no-oil product. When oil is changed, spices and flavors also will need to be altered. And the perception of acidity changes with less oil, too, offering yet another reason to tinker with the flavor system.  Simply reducing the amount of flavors used isn't necessarily the answer. Often, different flavors will have to be used that are designed specifically for use in no-oil systems. In short, it may be better to look at a no-oil dressing as a new product, rather than a reformulated product.  Today's more popular salad dressings contain herbs and spices suspended in the dressing ... offering eye and flavor appeal. Again, this can affect the formulation. What helps suspends those spices, generally, is the stabilizer systems.  While a refrigerated dressing might use fresh herbs and spices, shelf-stable products call for flavors more stable over a wider pH and longer time range. Traditionally, dehydrated was the way to go. Today, a popular option is individually quick-frozen products, because of their improved texture, flavor and color retention. (Turn to this month's Applications for more information on the different types of spices and spice ingredients, and how to use them.)  Spicy-hot flavors, such as salsa, are attracting interest, as are fusion flavors, which pair unlikely partners. Laning, for instance, has tested jalapeño-and-raspberry, roasted-garlic-and-peach, and a "hot and spicy" salsa dressing.  Tomato paste is ordinarily used in French dressings, but it can add a few calories. Sun-dried tomatoes also are in vogue. Adding tomato products can affect the overall acidity.  Flavor considerations also are based on a product's oil content. Full-fat dressings offer less of a flavor challenge. Oil is a good carrier for flavor, allowing initial and extended flavor release. In regular, full-oil dressings, flavors develop slowly on the palate. The tartness of the acid is perceived first (because it's water-soluble), then the other flavors come into play. Flavors can react differently with different oils and oil levels, however, and it can be difficult to compensate for an oil change.  Reduced-fat and fat-free dressings, on the other hand, present their own formulation and flavor problems. Flavors that work well in full-fat products most likely won't work as well in the reduced-fat or no-fat products. As a result, flavor components need to be "rebalanced." For instance, off-flavors may exist in a full-fat or reduced-fat product, but become more prominent when oil is removed.  Fat-free dressings offer a particularly difficult flavor challenge. The flavors might have a good initial impact, but then fade quickly because no oil exists to carry the flavor through.  Dry-mix dressings present yet another challenge. They're generally used right away and require ingredients that develop flavor profiles quickly. Yet it's not desirable to have flavors that are "too strong."  A wide range of flavor profiles might be developed through the use of yeast extracts, such as balsamic-type notes or tomato. Low-hydrolysis yeast extracts, which have less "meaty flavor" than often associated with yeast extracts, can help improve the mouthfeel and flavor perception of low-fat dressings. Yeast extracts can be used in low-pH salad dressings, to replace or reduce sodium chloride and monosodium glutamate.  Many of today's popular salad dressings, especially refrigerated dressings, also contain dairy-type flavors and ingredients, such as ranch-flavored and cheese-flavored dressings. Designers can use ingredients such as buttermilk, sour cream and yogurt. They can add cheese - for flavor and visual particulates. Or they can use alternatives to these traditional dairy ingredients.  For example, the Food Ingredients Division of Mid-America Dairymen, Springfield, MO, offers a product called Yogurtésse as a dairy-fat replacer. It can be used in fat-free and reduced-fat dressings, such as ranch or Caesar. A patented formula and process - it's acidified, not fermented - turns cultured skim milk into a versatile dairy-fat replacement. Although not lactose-free, it contains no fat or cholesterol, and just one-tenth the calories of ordinary fat (0.908 kcal/gram). It can replace the mouthfeel and viscosity supplied by cream, sour cream, mayonnaise, oil, and other fat-laden products.  One product line especially applicable to dry-mix salad dressings includes Sour Cream Buds™ and Cheese Buds (cheddar, gouda, parmesan, romano and blue), from Cumberland Packing Corp., Racine, WI. The enzyme-modified, encapsulated, and spray-dried "Buds" are water-soluble and possess high-intensity flavors that can replace some, or all, of the cheese solids in a salad-dressing mix. They contribute mouthfeel in no-fat systems, yet contribute only a minimal fat amount.When and how  Ingredient selection and synergy is important. But the real trick to salad-dressing success may be in the process , that is, when and how certain ingredients - such as salt, acidulants and stabilizers - are added.  For hot-filled dressings, a heat- and acid-stable gum should be chosen; heat can often make stabilizers more sensitive to pH. And for excessive shear, a shear-stable hydrocolloid is required.  Processing in a homogenizer provides a creamier, smoother product. But for a translucent or opaque product, a homogenizer or colloid mill shouldn't be used. A colloid mill, in fact, is the most common, and most effective means of processing a salad dressing. However, if a designer is making a salad dressing with particulates, a colloid mill cannot be used, or the piece identity will be lost.  There's no fast track to the perfect salad dressing. In the fast-changing world of food and beverage processing, things change too quickly for pat answers. Although highly complex products, salad dressings are not impossible to make. All it takes is know-how, good information from the get-go, and a lot of trial and error.Pay Attention to the Package  Today's salad dressings might be packaged in glass, plastic, foil or laminate pouches. And packaging choice plays a role in ingredient selection, too.  One company, for example, found that the fluorescent lighting common to supermarkets changed the color of one of its salad dressings - but only where the product was exposed to the light. Product behind the label suffered no color change. As a result, the dressing poured out in two colors - not very appetizing, to say the least. To correct this, the company made two changes. The first was in the product formulation, adding turmeric to stabilize the color. Later, it switched to an ultraviolet-barrier-equipped plastic bottle.  Often, marketing decisions can determine the packaging, which sometimes affects the formulation. For example, many of today's pourable-dressing bottles are fitted with a "shaker top," a plastic inner cap with a small hole that allows the salad to be dispensed slowly and evenly. For these package types, large-particulate flavorings may have to be reconsidered, because they might not fit through the shaker-top hole.  Also, more Americans are not only eating away from home, but consuming more salads. Packaged salad mixes, as well as supermarket salad bars, make single-serve packaging an important consideration. Single-serve pouches are used in foodservice applications for cost-and-portion control, too. Because of the smaller, limited portions, dressings intended for single-serve portion packs should be highly pourable and still provide cling. This can be achieved by using a low-viscosity stabilizer, or perhaps lower levels of the stabilizer. Shear-thinning properties might also be useful in this application.Back to top