Dropping Calories, Maintaining Taste and Functionality

According to statistics from the Centers for Disease Control and Prevention, Atlanta, obesity has increased from 12.0% of the population in 1991 to 19.8% in 2000. The National Health and Nutrition Examination Survey (NHANES) shows Americans are eating more, reporting that average caloric intake per day increased from 1,969 calories in 1978 to 2,200 calories in 1990. Despite the currently popular high-protein/low-carbohydrate diets, Chicago-based American Dietetic Association (ADA) spokesperson Dawn Jackson, R.D., Northwestern Memorial Wellness Institute, Chicago, says the ADA recommends reducing intake of calories as the best way to obtain and maintain permanent weight loss.

The increasing trend toward obesity, and its associated health risks, provides incentive and opportunity for the food industry to develop foods that are reduced in calories. The goal is to produce reduced-calorie foods that meet consumer expectations, something that eluded many of the fat-reduced and fat-free products introduced in the last decade.

Counting caloriesThe fat-free frenzy of the 90s is pretty much over. In the rush to join the bandwagon, many producers of reduced-fat foods found that their products fell short in taste and texture; few of these products have survived. One tactic was to replace fat with sugars and other carbohydrates to achieve a fat-free claim, sometimes providing the same amount of calories per serving as their full-fat counterparts. Consumers interpreted the low-fat and fat-free claims as I can now eat as much as I want without guilt, which was a mistaken idea as shown by recent weight statistics.

As the Atlanta-based Calorie Control Council maintains, calories count. A rose is rose by any other name and, a calorie is a calorie is a calorie, whether it comes from fat, protein or carbohydrate, says Jackson.

Calories are the units of energy that a food supplies, and calories derived from fats, carbohydrates and proteins are equivalent. Of course fat provides 9 kcal/gram, while carbohydrates and proteins provide 4 kcal/gram, but the energy that a calorie supplies from each of these sources is the same, regardless of its origin.

Some reduced-calorie products have already met with great success in the food industry. Reduced-fat milk, diet sodas and sugar substitutes are popular, but reduction of calories in food products with a higher level of solids, such as baked goods and dairy desserts, has proven more difficult. Calorie reduction in beverages is relatively easy, by replacement of sugars with water and high-intensity sweeteners. The complexity of replacing solids, such as fat and sugar, with noncaloric or lower-calorie ingredients requires not only the replacement of solids, but also the functionality of sugars, fats and related ingredients. For example, along with sweetness, sugars provide inexpensive bulk, control water activity (aw), increase shelf life, promote tenderness in baked goods, lower freezing-point depression and cause browning of heat-treated foods. Fats provide lubricity, texture, emulsification, a rich mouthfeel and a multitude of flavors. These are only some of the functionalities designers must replace.

Calorie reduction in high-solids foods usually requires a systems approach to address the functionality of each ingredient reduced or removed. No one universal replacement for calories, fat or sugars will do it all. After all, water, air and cellulose are the only ingredients that contain zero calories, and their substitution for constituents with multiple functionalities, such as fat and sugar, is usually limited. An arsenal of ingredients exists to reduce calories, but the trick is to match the functionalities of caloric ingredients with those of the calorie-reducers, while paying mind to the economic impact of specialty ingredients.

First, designers should identify a target calorie reduction and any other nutritional claims. Examine the major ingredients that make up a formulation and evaluate which of these contributes the majority of calories. Then determine their function(s) and identify what type of substitute ingredient will replace the functionality. Use formulation software to stage what if scenarios, along with some common sense to develop trial formulations. Several ingredients may be necessary to replace the functionality of major ingredients, such as fat and sugars. For example, fat provides emulsion stability in many types of products; substituting water, an appropriate emulsifier and a thickening agent, plus additional solids, might replace the emulsion capacity and bulk of the original fat.

Phasing out fatThe first area to attack when reducing calories is to take out the fat, because fat is the most calorically dense ingredient. Generally, complete fat removal is difficult; a more realistic goal is to focus on balancing fat reduction with retention of structure, texture and flavor using fat replacers.

The term fat replacer has come to mean any ingredient that replaces fat, and they fall into three general categories: carbohydrates, proteins and fat substitutes. Carbohydrates and proteins are fat mimetics, interacting with water to provide some of the functionality of fat. True fat substitutes are hydrophobic substances with molecular structures similar to conventional fats and oils, and can replace the full functionality of fat. These include salatrim (short-and long-chain acyl triglyceride molecule) and olestra.

Structurally, salatrim (sold under the trade name Benefat® by Danisco USA, Inc., New Century, KS) is composed of a triglyceride with two short-chain fatty acids (acetic, proprionic or butyl, C2-C4) and one much-longer-chain fatty acid (palmitic, stearic, arachidic or behenic, C16-22). Because of the unusual structure, it contributes only 5 kcal/gram, rather than the full 9 kcal/gram. Because salatrim is a saturated triglyceride, it is also trans-free. Terese ONeill, business director for Benefat, notes that the ingredient can replace other fats on a 1:1 basis, and that the product offers an easy way to reduce calories and remove trans fats with little, if any, reformulation.

Danisco has developed salatrim products for confectionery and bakery applications, and the ingredient has GRAS affirmation for confectionery, dairy products, margarine and spreads, baked goods, and snacks.

This fat substitute functions like a typical shortening in a formulation, says Dana Boll, bakery technical manager, Danisco. It creams into a bakery, cookie, or nutrition-bar mix, yet is very stable to oxidation. Newer forms are under development for dairy-based dips and frozen dairy desserts.

Olestra is a true fat substitute, able to stand in for both the functionality and flavor of triglycerides. Developed by Cincinnati-based Proctor & Gamble (P&G), olestra is constructed of a sucrose molecule esterified with fatty acids. It is nondigestible and, therefore, provides no calories. In 1996, FDA granted approval for the ingredients use in potato chips, crackers, tortilla chips and other snack foods. The approval was reviewed and confirmed in 1998. P&G sold its olestra manufacturing facility to Twin Rivers Technologies, Quincy, MA, last year, but still markets the product as Olean® for use in snack products.

Some individuals report gastrointestinal problems, such as cramps and loose stools, particularly after consuming large amounts of olestra. Although this has generated criticism in the press, studies published in many notable journals, including The Journal of the American Medical Association (JAMA) and the American Journal of Clinical Nutrition, have shown no significant difference in double-blind tests comparing the gastrointestinal effects between snacks fried in regular triglycerides versus those made with olestra.

Olestra also preferentially dissolves some fat-soluble vitamins when they are both present in the intestine at the same time, making them unavailable for adsorption. To address this issue, fortification of vitamins A, D, E and K are necessary in products formulated with olestra. In any case, the product labels of items manufactured with olestra destined for U.S. markets must state: This product contains olestra. Olestra may cause abdominal cramping and loose stools.Olestra inhibits the absorption of some vitamins and other nutrients. Vitamins A, D, E and K have been added.

Diacylglycerol oil has recently been introduced through a joint venture between Decatur, IL-based Archers Daniel Midland Company (ADM) and Andrew Jergens Company, Cincinnati, a subsidiary of Kao Corporation, Tokyo, and is marketed under the trade name Enova oil. Although it still provides 9 kcal/gram, initial nutritional studies have shown subjects eating fat calories from diacylglycerol oil versus fat calories from conventional sources (those with three fatty acids in a typical triglyceride/triacylglyceride structure) reduce weight and total body fat. More nutritional studies are underway to confirm these findings. Diacylglycerides perform the same as conventional fats in cooking and frying, baking, salad dressings, and dairy-based products.

Cutting with carbsCarbohydrate and protein fat mimetics interact with water to replace some of fats functionality. However, replacing fat with these may require some delicate balancing within a formulation. Additional water can act as both hero and villain, providing the smooth body and mouthfeel of fat when combined with a fat mimetic, but also decreasing shelf life, altering the freezing-point depression and reducing emulsion stability. Designers need to control water and somehow associate (or bind) it with other ingredients to alleviate texture, mouthfeel and shelf-life issues that arise when replacing fat with fat mimetics. Supplementing higher-molecular-weight ingredients such as starch, low-DE maltodextrin, gums and polydextrose with lower-molecular-weight sugars or polyols, and increasing the emulsifier level or using higher HLB (hydrophilic/ lipophilic balance) emulsifiers, can address some of these negative aspects. Products may require the addition of preservatives to control microbial activity.

Another aspect to consider is how the addition of water and a fat mimetic affects the rheology of a reduced-calorie food product. Matching rheological characteristics using a combination of fat mimetics goes a long way toward producing foods with texture and mouthfeel equivalent to their full-fat counterparts.

Carbohydrate fat mimetics include starch, maltodextrin, fiber, polydextrose, inulin and hydrocolloid gums. Each of these has some common and some unique properties that can help to replace fats in foods.

Starches, as well as maltodextrins, contain 4 kcal/gram, but their ability to associate with water to form gels and provide viscosity makes them economically viable fat replacers. Lower-DE maltodextrins can provide viscosity, as well as gel formation. Modified starches are particularly useful in replacing fats because they offer a variety of textures, viscosities and processing capabilities, as well as a range of acid stability and freeze/thaw stability. A combination of long-chain saccharides with acid-thinned starch helps in structure retention, as well as moisture management to optimize mouthfeel, says Mark Hanover, director, technical services, A.E. Staley/Tate and Lyle North America, Decatur, IL.

Fiber factsResistant starches have gained attention in the past few years, not only for their ability to provide fiber, but also for calorie reduction. Resistant starch is not digestible in the small intestine, but the body can ferment it in the large intestine similar to other dietary fibers. Resistant starches have been categorized as follows:

RS1. A physically inaccessible starch found in seeds and legumes.RS2. A granular, ungelatinized starch, such as that found in green bananas or potatoes, or in high-amylose starch.RS3. A retrograded starch formed after gelatinization.RS4. Chemically modified starches that resist enzymic digestion.

Commercial resistant starches contain from 20% to 60% total dietary fiber. Resistant starch is insoluble, has a low water-holding capacity and is suitable for cereal-grain-based products with lower levels of moisture. Applications for resistant starch include baked goods, extruded snacks, pasta, breakfast cereals and beverages.

National Starch and Chemical Co., Bridgewater, NJ, has developed Novelose® resistant starches, labeled as either maltodextrin or corn starch. Caloric values for resistant starches vary from 1.4 kcal/gram to 2.5 kcal/ gram depending on the level of fiber in the product making these products attractive for calorie reduction, as well as increasing fiber. Resistant starch can partially substitute for flour in bread and other baked goods, says Rhonda Witwer, nutrition business development manager, National Starch. In the case of high-fiber breads, vital wheat gluten is added to replace the functionality of the protein present in flour. Usage levels vary depending on the food product, but in general, anywhere from 3% to 20% replacement is recommended.

Fiber from sugar beets, cereal bran and hulls, citrus, chicory root, fruit, flaxseed, bamboo, powdered cellulose, and polydextrose all can reduce calories and increase fiber in foods. They can control water, form gels and add viscosity or texture, while providing dietary fiber. Some have 0 kcal/ gram, while others, such as inulin and polydextrose, supply reduced amounts.

Some adsorb many times their own weight in water, while others do not, an attribute developers may or may not find beneficial. Low water-binding capacity is desirable for baked goods, while a high water-binding capacity is more appropriate for beverages.

Playing with polydextrosePolydextrose is a multifunctional ingredient, manufactured as a random condensation polymer of glucose with 1 kcal/gram. It can contain up to 6% residual glucose and sorbitol monomers. As a mixture of oligo- and polysaccharides, it can reduce calories by replacing fat and sugars. Higher-molecular-weight polysaccharides supply the slippery mouthfeel of fat, while lower-molecular-weight oligosaccharides contribute the functionality of sugars. Polydextrose is 90% fiber and it can help manufacturers obtain source of fiber label claims, as well as reduce calories. Historically used to construct sugar-free, no-sugar-added and reduced-sugar dairy desserts, confections, and baked goods, newer applications include beverages and nutrition bars.

Recent developments for polydextrose include Litesse® Ultra, a reduced polydextrose manufactured by Danisco Sweeteners, Ardsley, NY. When polydextrose is manufactured, a number of reducing carbonyl groups remain and are able to participate in Maillard browning. Reduction of the carbonyl groups to alcohols (i.e. residual glucose to sorbitol) eliminates the browning reaction. The ingredient is recommended for clear beverages or in applications where significant browning is undesirable.

As with other calorie-reducing agents, a combination of polydextrose with other ingredients may be advantageous to maintain texture, flavor and structure. We often recommend a combination of Litesse with other polyols, depending on the application. says Donna Brooks, product manager, Danisco Sweeteners. In baked goods, we often recommend combining a 50/50 blend of Litesse with lactitol as a starting point to replace sugar. In confections and chocolate we also recommend use with other polyols, such as lactitol and maltitol. She notes that in ice cream, polydextrose is often used with sorbitol and maltodextrin, but the company has found that a combination of the reduced polydextrose with lactitol provides a cleaner flavor profile and a smoother texture. She adds that since the polydextrose does not have any sweetness of its own, the company suggests the use of a high-intensity sweetener.

Combinations of sugar replacers in dairy desserts are necessary to obtain the appropriate freezing-point depression, texture and mouthfeel. In baked goods, blending polydextrose at 1.0 kcal/gram with polyols at 0.2 kcal/ gram to 3.0 kcal/gram and/or maltodextrin at 4.0 kcal/gram is necessary to obtain the desired caloric reduction, along with controlling browning reactions, developing appropriate texture and balancing cost.

Adding inulinExtracted from chicory root, inulin is composed of fructose molecules linked by beta (2-1) bonds, generally with a terminal glucose molecule. These products are a mixture of oligomers and polymers of fructose with a degree of polymerization (DP) that ranges from 2 to 60. Because of different levels of free sugars, inulin products have a variety of caloric contents, ranging from 1.0 kcal/gram to 1.5 kcal/gram.

Some forms of inulin develop a creamy gel structure when subjected to shear in water. These gels are particularly suited to margarine-type spreads, cream cheese and processed cheeses. In addition to reducing calories, inulin has several other health benefits. It adds fiber, acts to increase calcium adsorption, and is a prebiotic promoting the growth of bifidobacteria in the gut all with a clean, slightly sweet taste.

Inulin acts as an invisible fiber, without gritty taste or cereal notes, says Kathy Niness, vice president of sales and marketing, Orafti Food Ingredients, Malvern, PA. The company produces Raftilose® Synergy 1, an enriched inulin product that is designed to maximize calcium adsorption. Because the ingredient is considered a fiber, both calorie reduction and a fiber claim are possible. Inulin has been successful in baked goods, and dairy products such as yogurt and milk drinks. Other applications include nutrition bars, confections, both hard and soft candies, chocolate, and dairy desserts.

Calorie reduction, by gumHydrocolloid gums do not typically add much fiber because they are used at low levels, mainly to control water. They provide texture and mouthfeel, prevent syneresis, help emulsion stability, and improve freeze/thaw stability.

Xanthan, guar, locust bean and gellan gum, as well as carrageenans, alginates and pectin, offer a wide range of viscosities, textures and gelling capabilities. Purified or derivatized cellulose products, such as microcrystalline cellulose, carboxymethyl cellulose, and methyl and hydroxypropyl cellulose, provide texture and stability. Combinations of gums and/or starches and maltodextrins are usually designed to obtain textures ranging from smooth pastes to stiff, brittle gels to soft, elastic gels. Combinations can also help to control cost.

Xanthan gum provides high viscosity, is very acid-stable and helps suspend particulates. At high levels, it can produce a long, slimy texture, so food technologists often combine it with other gums to modify viscosity. Guar and locust bean gums are widely used galactomannons that form synergistic combinations with xanthan gum. Guar provides synergistic viscosity with xanthan gum, with the maximum synergy occurring at about a 70:30 ratio of guar to xanthan. Locust bean gum forms elastic gels with xanthan and brittle gels with carrageenan. Combinations of xanthan, guar and locust bean gum are extremely versatile and cost-effective, and are used in many food applications.

Pectins are sold in high-methoxy or low-methoxy forms. Low-methoxy pectin requires the addition of calcium ions to form gels, and is used for low-sugar fruit spreads. High-methoxy pectin requires a certain amount of solids (sugar) and acid within a food system to form gels.

Gellan gum is a fermentation polysaccharide that can produce brittle (deacylated form) or elastic (acylated form) gels. Combinations of both forms provide a gel with the desired characteristics. Applications include low- and reduced-fat frostings and icings, bakery fillings, beverages, and low-sugar fruit spreads.

Sodium alginates are commonly used in dairy applications because of their reactivity with calcium ions to form stiff brittle gels. They can also form nonthermally reversible gels with calcium that do not melt upon heating. Propylene glycol alginate has reduced calcium reactivity, and is used in salad dressings as an emulsion stabilizer and in juice-based beverages.

Carrageenans come in several forms and are widely used to thicken, gel and stabilize food products. Among many other applications, they are particularly useful in dairy products because some varieties react with casein proteins or calcium to form gels, which can be brittle or elastic.

Microcrystalline cellulose (MCC) is derived from cellulose hydrolyzed with acid. Dispersing MCC in water by mechanical agitation forms 3-D networks of cellulose chains, producing soft, creamy gels with a fat-like texture. Blends of MCC with other hydrocolloids are coprocessed to increase functional properties. Methoxyl or hydroxypropyl cellulose gums are cellulose derivatives with a wide range of moisture retention, viscosity and film-forming properties.

Switching sugarsSugar alcohols, such as erythritol, sorbitol, maltitol, isomalt, lactitol, xylitol and hydrogenated starch hydrolysates, reduce calories because they contain fewer calories per gram than sucrose and corn sugars. The November 2002 Food Product Design article Sweet by Design offers an extensive review of these ingredients, as well as high-intensity sweeteners.

Physical properties for polyols, such as melting point, solubility, glass transition temperature and heat of solution (cooling effect in the mouth), vary considerably among polyols and can affect the final product, as well as processing parameters. Understanding and manipulating these properties to optimize reduced-calorie foods is key. Sweetening power and laxation effects also vary and require consideration.

Polyols offer other advantages: they are diabetic-friendly, and can allow for a complete replacement of sugar for a sugar-free or no-sugar-added claim.

The rich caramel flavor in baked goods results from Maillard browning and the substitution of polyols, which are not reducing sugars for sucrose, can result in a change or loss of color and/or flavor, depending on the food product and the particular polyol. If calorie reduction is the goal, rather than a sugar-free or no-sugar-added product, adding back small amounts of glucose or fructose can encourage browning. Addition of polydextrose or inulin will also encourage browning, as both of these products contain some residual reducing sugars.

Tagatose is an isomer of fructose derived from lactose with only 1.5 kcal/ gram. GRAS approval for tagatose is relatively new. It has prebiotic aspects as a functional-food ingredient, can replace the sweetness of sucrose and serve as a partial replacement for sucrose and corn sweeteners. Lower usage levels are recommended for beverages (1%), frozen dairy desserts (3%), grain products (10%), hard and soft candies (10% to 15%), ready-to-eat cereals (5% to 20%), and confections, frostings and icings (30%); higher levels are recommended for chewing gum (60%).

Tagatose has been reported to have flavor-modification properties when used with high-intensity sweeteners. Tagatose improves the flavor of some high-intensity sweeteners in beverages, causing an increase in onset sweetness and reducing bitterness, explains Josephine OBrien, business development manager, Arla Foods USA Inc., Union, NJ.

Tagatose is still a sugar, so manufacturers cannot label products made with it as sugar-free. However, it has a low glycemic index and is noncariogenic.

Sweetening the potBy far, the largest use of high-intensity sweeteners is in carbonated and still beverages, reducing calories by replacing sugars with water. Aspartame, saccharine, sucralose, acesulfame potassium and neotame are the five high-intensity sweeteners approved by FDA for use in the United States. Combinations of sweeteners can provide synergistic sweetening, such as that provided by aspartame and acesulfame potassium.

Newest in approval is neotame, which provides sweetness at levels of 7,000 to 13,000 times as sweet as sugar, and has been shown to have flavor modification or flavor-enhancing properties. At subsweetening levels, neotame modifies or masks undesirable qualities, such as bitterness, astringency and burning or cooling sensations. It is also said to reduce or eliminate beany flavors in soy products.

Developers may use sweetness enhancers, such as dihydrochalcones, thaumatin, glycyrrhizin, stevioside, maltol and ethyl maltol, to fine-tune flavors. These are approved for use at very low levels as sweetness modifiers or enhancers, not as sweeteners themselves.

Protein powerProtein sources for fat replacers include egg, soy, whey, gelatin and wheat gluten. Proteins are amphophilic, containing positively charged amino groups and negatively charged carboxylic-acid groups. Proteins can act as emulsifiers themselves, migrating to an oil and water interface, or as a dispersion aid for emulsifiers, interacting with both the hydrophillic and hydrophobic groups present in emulsifiers. Product designers can achieve maximum emulsifier functionality by allowing fat-replacement proteins and emulsifiers to interact with water before other ingredients are added to the formulation, although the same is true for many other ingredients, such as starches and hydrocolloids.

When microparticulated, proteins provide a smooth, slippery mouthfeel, which works well for foods with higher moisture contents, such as frozen dairy desserts, sauces and salad dressings. In lower-moisture systems, where replacing a smooth, creamy mouthfeel is less important, such as in baked goods, the microparticulation increases the surface area of the protein and, therefore, can increase its interaction with other ingredients. Controlled denaturation is another processing technique for manufacturing protein fat replacers.

Blends of carbohydrate and protein fat mimetics provide convenience and, in some cases, increase the functionality of ingredients in formulating reduced-fat or -calorie foods. One example is K-Blazer® from Kraft Food Ingredients Corp., Memphis, TN, a blend of protein, food starch, gums and emulsifiers making up a prepackaged fat-replacement system for baked goods. These types of combinations using protein, carbohydrates, and emulsifiers for fat replacement (and calorie reduction) replace the multiple functionalities of fat.

Blends can also help disperse small amounts of ingredients typically used at low levels. Emulsifiers, hydrocolloids and flavors sometimes do not achieve full functionality because they are not fully dispersed or hydrated; blending ingredients helps to alleviate the problem.

A fruity answerDesigners can consider fruit-based purees in baked goods as a system for fat reduction, and the purees are label-friendly. Plum puree in particular contains sorbitol, sugars and fiber that are dispersed in a matrix. The dispersion is more functional than adding each of the individual ingredients separately, which would also require them to be listed separately on the label. Naturally present malic acid acts as a flavor enhancer to extend flavor release, something fat also does. Depending on the formulation, small amounts of fat and/or emulsifiers can supplement fruit purees.

Fruit purees are supplied in hydrated form as dry powders. Although plum purees are very functional as fat replacers, lighter products, such as white cakes and muffins, benefit from the addition of pear or apple purees or powders to preserve the lighter color.

Adding back flavorOnce the target for calorie reduction is achieved, its time to address the flavor issues. Flavor companies have become increasingly sophisticated in replacing flavors either lost by the removal of fats and sugars or masked by calorie-replacement ingredients. Fats and sugars are flavor precursors in heat-processed foods, reacting with themselves or other ingredients to form hundreds of flavor compounds. Sugars undergo caramelization, and reducing sugars, such as fructose and glucose, cause Maillard browning when protein is present. Removal of sugars and replacement with nonreducing sugars may inhibit these reactions. Brown, caramel flavors, as well as sweetness enhancers, can help add back some of these complex flavors. Cooked-fat flavors, such as fried, baked, grilled, etc., are also available.

Fats and oils also act as solvent delivery systems for hydrophobic flavors. Fat helps to prolong flavor release, and when fat is removed, the flavor release tends to peak in a shorter amount of time.

Proteins can mask flavors and become a problem when protein levels are increased as a result of formula modification. Increased water content can force hydrophobic flavors to hide in the hydrophobic parts of a protein, making them weak and unavailable for flavor impact.

Flavor companies are very familiar with these challenges and have many products to mask off-flavors, enhance sweet notes, and extend flavor release to replace flavor lost in calorie reduction.

Baking considerationsReducing calories in baked goods entails fat and sugar replacement for calorie reduction, as well as adjusting emulsifier and leavening systems to account for additional water and differences in functionality of replacement ingredients.

In general, sweet baked goods contain up to 25% fat, making fat a prime target for replacement with lower-calorie ingredients. Replacing some of the fat with water and increasing the proportion of dry ingredients is a good way to get started, says Laurie Scheffers, a former technical service representative for Rhodia, Inc., Cranbury, NJ. Designers can make further refinements with fat-replacing mimetics, such as hydrocolloids and fiber, after initial trials. Its important to try to keep the flour-to-sugar ratio constant when reducing fat in baked goods, she continues. Otherwise, product identity may be lost.

Another approach is to substitute with emulsifiers, increase water content, and add a carbohydrate or protein fat mimetic for the fat that is removed. Higher HLB (hydrophilic) emulsifiers, such as sodium stearoyl lactylate, are suggested because of the products higher water content. Prehydrated emulsifiers also work well in fat replacement and ensure full functionality of the emulsifier.

Extra water can change the gelatinization temperature of wheat starch in flour and may result in textural differences. An increased amount of water lowers the gelatinization temperature, as is particularly evident in cookies. Their crisp, friable texture comes from a lack of water, which prevents the starch from fully gelatinizing. If too much water is present, a cakey, rather than crisp, cookie results, and these cakey cookies (and brownies) stale much faster because of their higher water content.

Baked goods vary in water content from about 5% to 40%, with cookies on the low end, and muffins and cakes on the higher end. The high solids content (largely sugar and flour) can make calorie reduction challenging. Brownies can contain as much as 50% sucrose, and the bulk of the sugar as well as the sweetness and other functionality that sucrose provides requires replacement.

Sucrose raises the gelatinization temperature of the wheat starch in sweet baked goods. It works in concert with the denaturation of egg and wheat proteins, along with the leavening system, to set the structure at a very particular time and temperature. If a sugar substitute replaces sucrose, it may change the gelatinization temperature, which affects the texture of both cakes and cookies. Lower-molecular-weight sugars and sugar alcohols decrease the gelatinization temperature, causing the structure to set too soon. This can result in lower volume and a tight, compact pore structure in cakes or muffins, and decreased spread in cookies. Higher-molecular-weight sugar substitutes, such as polydextrose and inulin, cause the gelatinization temperature to rise higher, and again results in lower volume in cakes, this time because the structure sets too late, with increased spread in cookies. The solution? Use a mixture of sugar substitutes to control the gelatinization temperature. Again, a systems approach using more than one sugar substitute works best.

A partial substitution of oil, rather than a lower-melting-point plastic fat, can help to reduce calories while increasing tenderness, because oil is more fluid and helps to increase the coverage of the fat. This is also seen in traditional baked-good formulations; cakes made with oil are more tender than cakes baked with shortening.

The majority of calories in breads comes from flour, not from sugar and fat, so the largest calorie reductions come from substitution of fiber for flour. Fibers can replace some of flours bulk with a zero-calorie ingredient, as well as bind water. Sometimes, addition of vital wheat gluten is necessary to add back the structure-building component of flour. Fibers can also act as nonreactive spacers, functioning to break up gummy protein networks caused by a lack of tenderizing agents, such as fat and sugar.

Fat concernsSalad dressings and sauces can contain substantial amounts of oil, and calorie reduction usually involves removing fat and adding water back. This can significantly impact flavor, texture, opacity and shelf life.

Flavor changes include loss of a suitable solvent for hydrophobic volatile flavors, and an increase in acid bite because the fat no longer is present to modify acid-containing ingredients, such as vinegar and lemon juice. Acid ingredients also act to inhibit microbial activity and dilution of acid may compromise shelf life. Flavor companies have developed different products, such as vinegar toners, that reduce the acids impact.

Opacity is lost because fat provides emulsification qualities; no fat means no emulsion. Opacifing agents can help alleviate the problem.

Reducing calories in deep-fat-fried foods, such as chicken, potatoes and doughnuts, calls for hydrocolloids. Gellan gum, specialized pectin and other hydrocolloids provide barriers against fat adsorption.

Fat adsorption can be decreased up to 25% to 45% says Wanda Jurlina, CP Kelco U.S., Inc., San Diego. In these methods, before a food is coated with either a breading or batter and fried, a hydrocolloid solution is prepared and sprayed onto it. The film prevents oil from soaking into the food. Incorporation of certain hydrocolloids, such as methylcellulose, into doughnut batter, and batter for fried fish and chicken can decrease oil adsorption. A gel forms when the product is heated, then reverses itself and ungels when cooled, again providing a barrier against oil adsorption.

The final cut Keeping these basic rules in mind will go a long way toward helping create a high-quality finished product:

Know your target. Quantify the caloric reduction (and other nutritional claims) you want to make before formulation starts.

Evaluate the original formulation, noting which ingredients provide the major amount of calories.

Determine the functionality of the major ingredients providing calories. Use a what if scenario and formulation software, along with common sense, to achieve a reduced- calorie claim (if desired) by replacing calorically dense ingredients with reduced- or no-calorie ingredients.

Think about the physical and molecular properties of the replacement ingredients. What functionalities do they provide and what functionalities can they replace?

Replace some or most of the major ingredients with calorie-reduced ingredients that mimic the function of each of these ingredients. Use a systems approach with several ingredients to balance the formula, control water and aw, and manage cost.

In the best of all possible worlds, calorie replacement would be easy and we would all be thin. Since this is not the best of all possible worlds, using carefully thought-out combinations of fat and sugar replacers for calorie reduction to replace both the bulk and functionality of these macroingredients is the principal strategy for obtaining successful caloric reduction in food products.

Teri Paeschke is a freelance writer and food scientist in the Chicago area. She has 13 years of experience developing sugar-free, low-fat and fat-free foods with food-ingredient and consumer-product companies. Paeschke recently received her Ph.D. in food science from the University of Illinois in Urbana-Champaign, and holds an M.S. in food science and a B.S. in chemistry from the University of Wisconsin-Madison.

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