November 1, 2004
By Ronald C. Deis, Ph.D.
Sugars, taken as an all-inclusive term and not just referring to sucrose, have become an important part of our diet. They supply energy in addition to sweetness. In foods, they add functionality from modifying texture, to producing color. Americans have developed such a sweet tooth over time that sugars are now a major part of the food supply and their high availability means that their cost is relatively low.
But times do change, and we now recognize that if we want to remain healthy in our old age, we need to change the way we eat. The Dietary Guidelines for Americans (1990) recommended the use of sugars in moderation, noting that sugars supply calories, but are limited in other nutrients. It should, then, come as no surprise that this is reiterated in the 2005 Food Guide Pyramid Committee recommendations.
In tight economic times, food processors need to keep an eye on the bottom line. But at the same time, they need to supply the market with products that meet consumer demand, whether it's satisfying the sweet tooth, reducing waistlines or just providing a satisfying product. This means that any effort to formulate with alternative sweeteners must overcome the difficult hurdle of cost/benefit.
Why make the switch?
· Weight control (reduction of calories supplied by traditional 4 kcal sweeteners, lowering of glycemic load);
Health advocates provide a compelling argument for reducing sugars in the diet. The 2005 Dietary Guidelines Advisory Committee Report issued in August 2004 states: "Compared with individuals who consume small amounts of foods and beverages that are high in added sugars, those who consume large amounts tend to consume more calories but smaller amounts of micronutrients. Although more research is needed, available prospective studies suggest a positive association between the consumption of sweetened beverages and weight gain. A reduced intake of added sugars (especially sugar-sweetened beverages) may be helpful in weight control and in achieving recommended intakes of nutrients." It also states that "the intake of carbohydrates (including sucrose, glucose, fructose, lactose and starch) contributes to dental caries by providing substrate for bacterial fermentation in the mouth."
We have seen an evolution within several markets, perhaps now settling into some definite ideas on how to improve the diet. We have evolved from the fat-free trend, through a high-fiber trend, then through a low-carb trend and into a more-moderate, better-for-you market that says more about "reduced" than "free." Throughout these trends, the problem has been the perceived marketing value of the term "zero." It seems that whenever we see value in moderation, that somehow translates to "zero" even though "reduced" or "low" is the operative term. In the case of sugar, diabetics can consume some sugar and other carbohydrates, and dieters should eat less-refined carbohydrates. The low versus zero approach also results in more-palatable products with better repeat-purchase potential.
Depending on where you look in the world, viewpoints now are focused toward reduction of calories, reduction of added sugars and reduction of the overall glycemic load in the diet. In addition, the Institute of Medicine has recommended an increase in fiber consumption -- 38 grams/day for men less than 50 years of age, 25 grams/day for women of the same age.
How can we achieve these goals? They are somewhat interrelated: Formulators who want to replace high-calorie, high-bulk sweeteners can do so with ingredients or systems that deliver the appropriate sweetness level as well as the appropriate bulk and functionality. Often that includes fiber options, with many available among soluble or insoluble fibers. In terms of sweeteners, they can also find many available options. Using sucrose as the standard and assigning it a sweetness value of 1, a number of bulk sweeteners that are not considered "sugars" have sweetness values equal to, or less than that of, sucrose. If more sweetness is desired, high-potency sweeteners may be considered.
The gold standard and beyond
Because of its availability, long historical use, ease of use and low cost, sucrose has become the sweetener of choice in foods. All of our recipes are based on sucrose, and its interactions with other ingredients, processing characteristics, sensory characteristics and shelf-life characteristics have also become the standard by which we measure all other sweeteners. Sucrose contributes certain characteristics to our foods that affect appearance, storage, processing, flavor, texture and reactivity with other ingredients. When we replace it, we must factor in how to compensate for those changes since the net results have become the gold standard to consumers.
Other sugars commonly found in foods in addition to sucrose include glucose, fructose, lactose and maltose -- naturally found in fruits, vegetables, flour and cereal products, and dairy products. In addition, product developers work with corn syrups and hydrolysates, honey, molasses, and fruit-juice concentrates, which also contain these sugars.
Many types of corn syrup, maltodextrins and high-fructose corn syrup (HFCS) are derived from corn starch through hydrolysis. Starch can be hydrolyzed by acid and/or enzymes under various conditions to yield a range of different polymeric mixtures that include mono-, di-, and trisaccharides, as well as higher saccharides. These ingredients are generally defined by dextrose equivalence (DE), which measures the total reducing sugars calculated as a ratio to dextrose. (Dextrose has a DE of 100.) Corn syrups are commonly identified by their DE (e.g., 36, 42 and 63) and their Baumé, an old method of determining density expressed in degrees and related to total solids. For example, "43/42" is a 43? Baumé, 42 DE corn syrup (although some companies use the opposite order for Baumé and DE).
Product developers really need to be aware of degrees of polymerization (DP) of corn sweeteners as well, which refers to the carbohydrate profile of the syrup (DP1 = glucose, DP2 = maltose, DP3 = maltotriose, etc.). Because it reflects the composition, DP more-accurately measures the sweetness and functional characteristics of the syrup (viscosity, osmolality, freeze-point depression, etc.) than DE. As a reference, sucrose is DP2 with a molecular weight (MW) of 342. An decrease in DP or MW will increase osmolality or freeze-point depression. Decreasing MW will also decrease viscosity. Conversely, as larger polymers are added, MW will increase, which will increase viscosity, decrease osmotic concentration, and increase the freeze-point of the product. Also, in general, as MW decreases, humectancy and crystallization will increase. All of these properties will also depend on the mix of saccharides in the polymer distribution.
Lower-DE products have a higher percentage of higher-molecular-weight polymers in the mixture, which impacts sweetness, viscosity, moisture control and a number of other characteristics in the food system. Higher-DE syrups are sweeter and less viscous than syrups with a lower DE. Hydrolysates with a DE less than 20 are called maltodextrins, which manufacturers use for their bulking characteristics in a number of foods. Formulators often select hydrolysates based on rice, potato and tapioca, available as syrups or maltodextrins, for use in more-natural or non-GMO products. Brown-rice syrups, readily available in a range from 28 DE to 60 DE, are also often preferred in natural or organic products.
When switching from a corn product to an equivalent syrup, there will be noticeable changes due to the differences in saccharide composition. For instance, brown-rice syrup contains a high percentage of maltose and higher-DP carbohydrates. The method of hydrolysis can also cause wide differences in saccharide distribution, affecting DP and DE. Acid hydrolysis is relatively random, and enzyme hydrolysis is specific, dictated by the enzymes chosen.
More-complete hydrolysis of starch, plus an isomerization process, leads to the production of high-fructose corn syrup, usually available at 70% to 77% solids and at 42%, 55% and 90% fructose levels. The majority of the remainder is dextrose. (For example, an HFCS might contain 55% fructose, 41% dextrose, 2% maltose and 2% higher saccharides.) HFCS, due to low cost, availability and ease of use, have become the fastest-growing group of "sugars" on the nutritional label.
Keep in mind that while sucrose is a disaccharide, fructose is a monosaccharide with half the MW. HFCS is a mixture of fructose and glucose, both monosaccharides. The resulting difference in MW can cause differences in colligative properties, such as osmolality and freeze-point depression, and can also affect properties of other ingredients (e.g., starch-gelatinization temperature). Sweetness and flavor quality will also be affected in certain applications due to the differences in these characteristics for sucrose versus fructose and glucose.
Crystalline fructose is processed from HFCS into a more-pure (99.5%-plus) fructose powder. Crystalline fructose has 117% the sweetness of sucrose, and manufacturers can combine it in a 50/50 blend with sucrose to obtain a product with 128% the sweetness of sucrose alone. Crystalline fructose has a faster sweetness onset than either sucrose or high-potency sweeteners, which can create synergistic mixtures.
Going natural and organic
"Malt is the dried grain resulting from controlled germination of cereal grains, usually barley," says Joe Hickenbottom, vice president, sales and marketing, Malt Products Corporation, Saddlebrook, NJ. "Malt extracts of malt syrups are concentrates of the water extract of dried malt. Liquid extracts or syrups are also available in the dried form. If barley is the only grain used, the products are termed 'malt extracts.' If other cereal grains are included with barley, the products are 'malted cereal syrup' or 'extract of malted barley and corn,' in either liquid or dried form. Most malts are slightly more than half as sweet as sucrose. The saccharide profile of malt extract, for example, is 1% to 2% fructose, 7% to 10% glucose, 1% to 3% sucrose, 39% to 42% maltose, 10% to 15% maltotriose, and 25% to 30% higher saccharides. Since perceived sweetness basically is attributed to the mono- and disaccharides fructose, glucose and sucrose, you can see why the overall sweetness of malt extract is lower than that of sucrose. With sucrose arbitrarily rated at 100 in sweetness value or scale, malt extract is about 55. Malt syrups, those with cereal adjunct, are rated at about 65. Keep these sweetness values in mind if the application you propose needs sweetness, and you want to use a type of malt."
For example, processors derive fruit concentrates and sweeteners -- combinations of simple sugars, such as fructose, glucose and sucrose -- from grapes, apples, peaches and pears. Processors make brown-rice syrup, which contains about 50% maltose, from fermented brown rice and sprouted whole barley. Barley-malt syrup is also available at about 65% maltose.
When switching from sugar or corn sweeteners, the differences in sweetness quality and intensity might become noticeable. The difference in saccharide compositions will impact other ingredient characteristics within the product, such as starch gelatinization temperature and the extent of protein denaturation. In a cookie application, this will affect characteristics like spread, height and color, as well as textural characteristics, including hardness or softness, moistness, amount of crumbling, and density.
Fruit can add sweetness, as well as other potentially beneficial attributes, to products. "Dried plums," notes James M. Degen, consultant for the California Dried Plum Board, Sacramento, "contain about 62.7% carbohydrates per 100 grams. They contain, on the average, 23 grams of sorbitol as well as 6 to 7.5 grams of fiber. When compared to fresh d'Agen plum, their source material, dried plums contain more sugars due to dehydration. However, most of the sucrose has been hydrolyzed to glucose and fructose during processing." Dried plums are unique in their naturally high sorbitol content (15%). Sorbitol is an effective humectant, which helps keep bakery products soft and moist over an extended shelf life.
Fruit purées can also contribute functional properties. Because they naturally contain hydrocolloids and humectants, which control moisture, fruit purées can also influence product texture. Fruit-juice concentrates are another option for natural products. They are available within a usable Brix range (65? to 75?), and their carbohydrate content and relative sweetness varies with the raw material. Product designers often use fruit-juice concentrates for their flavor, color and name appeal, so these should be the major considerations in the selection process.
Honey, another natural product, adds flavor as well as familiarity. According to the National Honey Board, Longmont, CO: "On the average, honey is 1.0 to 1.5 times sweeter (on a dry weight basis) than sucrose. Liquid honey is approximately as sweet as sugar, yet it contains only 82.4 grams of carbohydrates/100 grams (versus 100 grams for sucrose) and provides only 304 kcal/gram (versus 400 kcal for sucrose)." The reason for this is the predominance of fructose, which makes up about 38% of the carbohydrates in honey. Glucose weighs in at about 30%; sucrose at about 1.3%. Honey can come from a variety of sources (clover, buckwheat, avocado, sage, etc.), so the flavor and color can vary.
Processors create another well-known natural sweetener, maple syrup, by tapping maple trees and then extracting and evaporating the sap. Maple sap itself is also a favorite regional sweetener. Maple syrup, predominantly sucrose, is evaporated to a Baumé or Brix (in commercial process) and either sold as a syrup or further evaporated to a granulated form.
The syrup can vary depending on the region it comes from. According to the Cornell Sugar Maple Research and Extension Program, Cornell University, Ithaca, NY: "The biggest difference between New York and Vermont maple products is the label. Producers in Vermont generally bottle their syrup at a slightly higher sugar content (66.5?Brix) than producers in New York (minimum of 66?Brix, although many New York producers go higher). A higher Brix reading gives the syrup a little more viscosity, which consumers generally prefer. Higher sugar content (over 67?Brix) may result in sugar crystals in the syrup. Maple syrup must meet exacting standards for purity. High-quality Grade A syrup can be made only by the evaporation of pure maple sap, and by weight may contain no less than 66% sugar (66?Brix). Grade A maple syrup is classified according to its color. The darker the syrup, the stronger the maple taste."
Molasses, the concentrated liquid extract of sugar refining, is another popular natural product -- especially in baked goods. Sugar-beet molasses has a very astringent off-flavor and aroma, so the molasses used in food is sourced from sugar cane. It contains about 50% to 75% total sugars: 25% to 35% sucrose and the balance is invert. It also contains 3% to 9% protein and 8% to 12% ash in a 70%- to 80%-solids syrup. Molasses, depending on the grade and origin, can provide a wide range of color and flavor choices as an alternative to refined sugar.
Another new sweetener, tagatose, was launched in the United States in 2003. This monosaccharide has 92% the sweetness of sucrose, is self-determined GRAS, and delivers 1.5 kcal/gram. Tagatose is highly soluble (about as hygroscopic as sucrose), is Maillard-reactive and caramelizes to fructose at low temperatures. Its melting point is relatively high (134?C), but its glass-transition temperature is low. Tagatose is noncariogenic and nonglycemic, but is classified as a sugar by FDA. SweetGredients Gmbh and Co., Brunswick, Germany, manufactures tagatose as a joint venture of Arla Foods Ingredients amba and Nordzucker AG.
Before moving on to sugar alternatives, it might be important to mention a couple of crossover products that seek to reduce sugars while maintaining sweetness. In the United States, Chicago-based Merisant has launched Equal Sugar Lite, which claims to be the first blend of sugar and artificial sweetener for cooking and baking. Also, Silver Spoon, Peterborough, England, introduced Silver Spoon Light, which contains maltodextrin, aspartame and acesulfame-K, with 25% less calories than sugar.
Monosaccharides. Sorbitol, a six-carbon polyol available in both liquid and crystalline form, finds wide use in the oral-care industry and in chewing gums, and acts as an excellent humectant in baked goods. It is relatively low in cost, has a high level of solubility, and provides 2.6 kcal/gram.
Mannitol, a six-carbon polyol available in crystalline form, is relatively nonhygroscopic with very low solubility. Manufacturers use mannitol as a plasticizer and dusting agent, as well as a tablet excipient. This low-calorie sweetener (1.6 kcal/gram) has a low laxation threshold (20 grams/day), limiting its use at high levels.
Xylitol, a five-carbon polyol derived from xylose, is crystalline, but also comes in liquid form (with sorbitol). It has a sweetness equal to sucrose, provides 2.4 kcal/gram, and is cariostatic. All polyols are noncariogenic, but xylitol prevents bacterial attachment and promotes tooth remineralization.
Erythritol, a four-carbon polyol derived from glucose through fermentation, delivers 60% to 70% the sweetness of sucrose, has a caloric value of 0.2 kcal/gram, and is available in crystalline form. Erythritol is relatively nonlaxative since, during digestion, the consumer absorbs and excretes it through the urine. It is relatively insoluble and has a high negative heat of crystallization (cooling effect) compared to sucrose.
Disaccharides. Maltitol, a disaccharide polyol with 90% the sweetness of sucrose and a caloric value of 2.1 kcal/gram, is available in crystalline form at several purity levels. It has very good solubility and virtually no cooling effect.
Isomalt, a disaccharide mixture with 40% the sweetness of sucrose and 2.0 kcal/gram in the United States, has virtually no cooling effect and low solubility. Isomalt forms a very stable crystalline structure, which eliminates cold flow in sugar-free confections.
Lactitol, a disaccharide polyol with 30% to 40% the sweetness of sucrose and 2.0 kcal/gram, has moderate solubility and little cooling effect. It has a laxation threshold of 20 to 50 grams per day.
Mixtures. Polyol mixtures, usually available in the form of syrups or solutions, can effectively accomplish the roles of corn syrups and maltodextrins in foods.
"Since polyols are derived from traditional carbohydrates," notes Peter Jamieson, manager, technical service, SPI Polyols, Inc., New Castle, DE, "there are maltitol/polyglycitol syrups that have characteristics and functional properties analogous to various DE values of corn syrups. These properties are dictated by the amount of maltitol and sorbitol versus the longer-chained polyols present. Maltitol syrups are generally identified as having greater than 50% maltitol and less than 8% sorbitol on a dry basis. Anything outside that range is considered a polyglycitol syrup (previously known as hydrogenated starch hydrolysate, or HSH)." The good news is that these mixtures can be customized to deliver a range of 30% to 90% sweetness based on sugar, and their higher molecular weight increases the laxation threshold.
Dry polyglycitol powders based on maltodextrins as precursors have virtually no laxative properties. "The properties of these mixtures enable a food-product developer to replace corn syrups and maltodextrins in a formulation with no loss in functionality," says Jamieson. "Crystalline polyols can replace all or part of the sucrose or other sugars in a formulation to reduce sugars while maintaining full-sugar characteristics."
Crystalline and soluble polyol mixtures work well with soluble fibers, such as polydextrose and branched maltodextrin fibers, to increase dietary fiber in a formulation. They also work well with resistant starch or other insoluble fibers.
Oligiosaccharides are another ingredient category that can serve as a bulk sugar replacer. For example, The Roxlor Group, Wilmington, DE, has a line of inulin-based ingredients with the same sweetness as sucrose that can be used as a 1:1 replacement for sugar. The products, which contain more than 85% dietary fiber and have a caloric value of about 2 kcal/gram, consist of a synergistic blend of the prebiotic soluble fiber inulin and a proprietary mung-bean extract. Inulin, a natural food ingredient obtained from the root of a chicory plant, is a mixture of oligo- and polysaccharides composed of fructose units joined together by ß(2-1) linkages.
Production of the mung-bean extract involves the physical enrichment of sprouted mung-bean plants with small amounts of acesulfame potassium, a high-potency sweetener. The absorption of the sweetener into the plant's structure masks the undesirable aftertaste of the acesulfame potassium while maintaining its sweet taste. The manufacturer then processes the plants into an enriched mung-bean extract, and then blends it with inulin.
"Our ingredients make sugar replacement a simple, one-step process, while providing both health and sensory benefits," states Robert H. Veghte, business manager, Roxlor. "The prebiotic fiber promotes the growth of beneficial bacteria in the large intestine and is associated with improved calcium and mineral absorption. From a functional standpoint, the products improve texture, mouthfeel and overall taste, and eliminate the need for other high-intensity sweeteners. When combined with sugar alcohols, our products improve the texture and remove the off notes and minty aftertaste often associated with some polyols."
The human body cannot digest or metabolize sucralose, so it yields no calories and is safe for diabetics. Its flavor profile is similar to sugar, with no unpleasant aftertaste. It has been approved as an all-purpose sweetener in the United States and has acceptance in over 50 countries. On Feb. 19, 2004, McNeil Nutritionals, Fort Washington, PA, and Tate & Lyle PLC, London, announced that Tate & Lyle would become the sole manufacturer of Splenda® brand sucralose, and would be responsible for food and ingredient sales, while McNeil Nutritionals would continue to market the product to consumers and health-care professionals.
Highly soluble with excellent overall stability, sucralose is available as a clear, colorless, highly soluble liquid concentrate that is approximately 150 times sweeter than sugar or as a white to off-white, practically odorless, crystalline powder that is approximately 600 times sweeter than sugar. Due to excellent up-front work by McNeil Nutritionals, the sweetener has gained excellent acceptance by health-care professionals, and has established a very positive image.
Aspartame (L-alpha-aspartyl-L-phenylalanine methyl ester), a low-calorie substance approximately 200 times sweeter than sucrose, used to sweeten a wide variety of low- and reduced-calorie foods and beverages, including low-calorie tabletop sweeteners. It is composed of two amino acids: aspartic acid and phenylalanine (as the methyl ester).
According to the Aspartame Information Center (www.aspartame.org, maintained by the Calorie Control Council, Atlanta), "aspartame is consumed by over 200 million people around the world and is found in more than 6,000 products, including carbonated soft drinks, powdered soft drinks, chewing gum, confections, gelatins, dessert mixes, puddings and fillings, frozen desserts, yogurt, tabletop sweeteners, and some pharmaceuticals, such as vitamins and sugar-free cough drops." It should be remembered that, although aspartame does have good heat stability in many applications, food developers must be aware of the effects of pH, time, moisture and temperature on its stability.
Acesulfame-K, a general-use, white, crystalline powder approximately 200 times sweeter than sucrose, is approved for use in all product categories. It has an intense, sweet taste with an early onset -- but a bitter off-taste at high levels. It has excellent solubility and stability, and is approved in more than 100 countries.
FDA approved acesulfame-K as an all-purpose sweetener in January 2004. Since then, Nutrinova, Somerset, NJ, has advocated blending it with other sweeteners to take advantage of its sweetness and stability to enhance its properties and those of other sweeteners. The company claims that, in reduced-sugar beverages (sugar replaced by 50% or more), blends with acesulfame-K -- such as acesulfame-K/sucralose/ HFCS55 or acesulfame-K/aspartame/HFCS55 -- gives a taste profile that mirrors conventional sweeteners more closely than the combination of a carbohydrate source with only one high-intensity sweetener.
A new, intense sweetener developed and marketed by Holland Sweetener Company, Geleen, the Netherlands, Twinsweet(TM), also takes advantage of a multisweetener concept in a single ingredient. It dissociates immediately on solution to release aspartame and acesulfame. Once in solution, this sweetener behaves the same as a mixture of aspartame and acesulfame-K with the potassium removed. To date, the company is free to market it in North America where it falls under the existing regulations for aspartame and acesulfame-K. Products containing Twinsweet should be labeled as "aspartame-acesulfame." It is also approved in European Union countries, China, Russia, Australia and New Zealand.
FDA approved neotame in 2002 as a general-use sweetener and flavor enhancer in foods and beverages, and it has received approval in a number of other countries. The NutraSweet Company, Chicago, derives neotame from a dipeptide composed of phenylalanine and aspartic acid. This off-white crystalline powder is more readily soluble than aspartame in some food-system solvents and is 7,000 to 13,000 times sweeter than sucrose. Its stability is similar to aspartame -- excellent in dry, finished products, but subject to degradation in the presence of moisture. The rate of degradation is pH-, temperature- and time-dependent. Neotame lends itself particularly well to blending with other sweeteners, including both nutritive and nonnutritive sweeteners.
One sweetener alternative, saccharin, has come under scrutiny in the past because of questions about its safety. However, in December 2000, federal legislation was signed to remove the saccharin warning-label requirement on saccharin-sweetened foods and beverages in the United States. Saccharin, approved in more than 100 countries around the world, has been reviewed and determined safe by the Food and Agriculture Organization of the United Nations and World Health Organization Joint Expert Committee on Food Additives, as well as the Scientific Committee on Food of the European Union. This stable, low-cost sweetener provides approximately 300 times the sweetness of sucrose. Its most prominent use has been in tabletop sachets and in blends with aspartame for fountain use.
Another formerly popular sweetener, cyclamate, has had its ups and downs in this country. Although it was banned in 1970, cyclamate is still used extensively outside the United States. The Calorie Control Council and Abbott Laboratories, Abbott Park, IL, continue to pursue the reapproval of cyclamate. Its sweetness is relatively low compared to high-intensity choices (30 times sucrose), but it is synergistic with a wide array of sweeteners and polyols and would be extremely valuable in sweetener blends. It is probably best known for the excellent aspartame/cyclamate blends on the market prior to 1970.
The important thing to remember when switching sweeteners is to consider the reasons for reformulation. All too often, a food-product developer will look at multiple options and then include most of them in the product. It is important to remember the common origins of many of these sweeteners and to really examine their chemical characteristics. Inclusion of too many ingredients may simply be redundant. In a review of the options available (and I certainly have not covered all of them here), the choices can be overwhelming, but finding the best fit depends on what you need to achieve in the finished product, be it flavor, cost, functionality, or nutrition and calories.
Ronald C. Deis, Ph.D., is the vice president of technology at SPI Polyols, Inc., New Castle, DE. He has 25 years of experience in the food industry, both in food-ingredient and consumer-product companies, and is an active member in a number of trade associations. He has been a short-course speaker, worked as a freelance writer covering a number of food-science-related subjects in food journals, and contributed chapters on sweeteners and fat replacers for several books.
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