How Sweet It Is: Functional Sweeteners

How Sweet It Is: Functional Sweeteners

by Kim Schoenhals

Ingredients added to foods and beverages for the sweetness they impart also add functionality. From altering the mouthfeel and viscosity to enhancing flavor and humectancy, sweeteners offer a range of function for every conceivable food or beverage product.Candy, cake, pie, soda--these are the things that make mouths water. Sweetness is something people crave and seek out, and manufacturers are more than willing to supply it. Americans consume about 64 pounds of sugars per year, according to the U.S. Department of Agriculture's (USDA) Continuing Survey of Food Intake of Individuals. However, according to the Sugar Association, this number is a misrepresentation of "sugar" consumption. Technically, the only sugar that can be labeled as such is sucrose, according to the association, which estimates Americans consume 29 pounds per year of actual sucrose.

"Historically, sugar (sucrose), the natural carbohydrate derived from sugar cane and sugar beets, has been the predominant sweetener," according to the Sugar Association. "But over the past 20 years, a slew of new caloric sweeteners have been developed and introduced to the market, including fructose, glucose, high fructose corn syrup and maltose."

While probably not many consumers spend much time contemplating their yearly intake of sucrose versus other caloric sweeteners, there are many technical differences and functional considerations regarding the various types of sweeteners available for food and beverage use.

Sweeteners can be broken down into several categories: nutritive and nonnutritive, low- and high-intensity, and natural and artificial. Nutritive sweeteners, such as sucrose, are metabolized by the body and provide calories, while nonnutritive sweeteners, such as sucralose, are not metabolized and are non-caloric. In many cases, nutritive sweeteners are also low-intensity and natural, while nonnutritive sweeteners tend to be high-intensity and artificial. As with most rules, exceptions do exist. Stevia, for example, is a high-intensity, nonnutritive sweetener that is considered natural.

So, how do manufacturers go about selecting a sweetener--or sweeteners--for food or beverage applications? Many times, it is the functionality, both in terms of health and physical attributes, which draws manufacturers to particular sweeteners over others, in addition to application needs.

A Matter of Function

Sucrose is generally used as the proverbial yard stick by which all other sweeteners are measured. In terms of sweetness, most sweeteners are described as a percentage of (or a number of times) the sweetness of sugar. Nutritive sweeteners tend to be as sweet as or less sweet than sucrose, while nonnutritive sweeteners are often several hundred times sweeter.

"Nutritive sweeteners are carbohydrates that impart sweetness to some degree, usually less than that of sucrose," said Kenneth Meincke, vice president of sales and marketing at Copenhagen, Denmark-based Danisco, which supplies xylitol, a naturally occurring nutritive sweetener.

Aside from the obvious sweetness factor, sweeteners have several functions in food and beverage products. They can reduce calories, serve to enhance flavor by masking off-notes, and add body, bulk, texture and viscosity. They can also impart health and nutrition benefits.

"Sweeteners, whether they are caloric or non-caloric, low-intensity or high-intensity, offer a lot of functional properties to food products, not just sweetness," said Bryan Tungland, vice president of scientific and regulatory affairs at Monmouth Junction, N.J.-based Sensus America, maker of Frutafit brand inulin and Frutalose brand fructooligosaccharides (FOS). He noted sweeteners affect the microbiological safety of food products, provide browning characteristics, viscosity, body and mouthfeel, and affect the dielectric constant (a measure of how molecules move when they are energized, which affects a food's ability to heat).

Meincke added, "Sweetness is not necessarily the primary reason for using nutritive sweeteners, as they will most often be included in formulations for their functional benefits, while at the same time reducing the impact of calories or carbohydrate load, such as in a low-glycemic diet. Nutritive sweeteners have bulk and are used in the same proportions as sugar or similar carbohydrates providing body, structure and texture to food products. They may also be used in conjunction with nonnutritive sweeteners to enhance the sweet taste."

Xylitol, for example, has the same sweetness and bulk of sugar with 40-percent fewer calories. It is known for its rapid rate of dissolution, which gives it a "quick hit" of sweetness, and it also has a perceived cooling effect, which enhances mint and fruit flavors, according to Meincke. In addition, xylitol is hygroscopic and adds humectancy.

One of the benefits of using xylitol in a food or beverage application, according to Meincke, is that it is a low-glycemic sweetener metabolized independently of insulin, meaning it does not cause a sharp increase in blood sugar levels or the associated serum insulin response. This makes xylitol well-suited for sugar-free and diabetic applications.

A big draw in the search for an alternative to sucrose is making low- and non-caloric foods or beverages. There is a growing market for sugar-free (which only means sucrose-free, according to the Sugar Association) and low-calorie products, especially in the United States, where more than 60 percent of the adult population is overweight and 25 percent is obese. In replacing sugar in a food or beverage, depending on the sweetener, there may be several manufacturing issues to address.

"There are a number of bulk properties of sugar that need to be adjusted for when replacing sugars with any low-calorie sweetener," said Carolyn M. Merkel, Ph.D., executive director of ingredient technology at New Brunswick, N.J.-based McNeil Nutritionals, maker of Splenda brand sucralose. "These properties include humectancy, browning and bulk, among others. If the product contains significant amounts of water, frequently the bulk properties can be made up with the addition of more water. However, if the product is lower in moisture, then the formulation needs to be adjusted to account for the difference in bulk."

According to Merkel, no processing adjustments are necessary when replacing sugars with sucralose--a nonnutritive, high-intensity sweetener derived from sucrose--because it is completely heat-stable. "Sucralose has the clean, sweet taste of sugar without the calories of sugar," Merkel said. "It offers a manufacturer the option to provide sweetened foods and beverages that taste good but don't have the added calories or carbohydrates associated with sugar."

Another nonnutritive, high-intensity sweetener on the market for low-calorie applications is acesulfame-K (Ace-K). According to literature from Somerset, N.J.-based Nutrinova Inc., maker of Sunett brand Ace-K, the company's partial sugar replacement concept involves replacing part of the nutritive sweetener content of a product with Sunett or a combination of sweeteners. Up to 80-percent sugar replacement is possible, according to the company, while still maintaining mouthfeel, taste and sensory properties.

"Partial sugar replacement means lower overall sweetening costs, reduced storage requirements and lower logistical costs," according to Nutrinova. "Syrups in which sugar is partially replaced can be produced in higher concentrations and brought to market in smaller container sizes."

Research conducted by Nutrinova indicated carbonated lemon-lime beverages sweetened with a ratio of 30-to-70 Sunett-to-aspartame blend maintained quality and flavor in a fashion similar to the sucrose control beverage--and more effectively than six other sweetening systems.

Some ingredients that impart a touch of sweetness to food and beverage products may not actually be classified as sweeteners. Trehalose, inulin and oligosaccharides are a few such ingredients. These are often categorized as functional carbohydrates, functional fibers, sweet bulking agents or, in the case of inulin and FOS, prebiotics. These ingredients are often used in combination with sweeteners to enhance mouthfeel and body, as well as to add a touch of functionality.

Two sweet bulking agents available on the market today are Beflora and Beflora Plus. These ingredients, imported by Manasquan, N.J.-based Roxlor International and distributed in the United States by Wayne, N.J.-based Triarco Industries Inc., are a combination of oligofructose, mung bean extract and a very small amount of Ace-K.

The functionality Beflora and Beflora Plus add to food and beverage applications is enhanced taste, low-calorie sweetness and improved gastrointestinal health as a function of the prebiotic fiber. Beflora and Beflora Plus also affect mouthfeel, hold moisture and add texture to finished products, according to Mark Anderson, Ph.D., director of R&D at Triarco.

While Beflora and Beflora Plus may not be suitable for acidic applications (pH 3 and lower), they are good candidates for mixing with other sweeteners, according to Chuck Messenger, president of Roxlor International. "We generally say artificial, or nonnutritive, sweeteners are good candidates for blending with Beflora Plus," Messenger said. "And it's normally a 75-25 blend--75 parts artificial sweetener and 25 parts Beflora Plus. Beflora has a great capacity to round out the mouthfeel and flavor and eliminate the metallic taste you can get when using a nonnutritive sweetener. It also works particularly well in soy-based products to mask the beany taste of soy."

Tungland noted inulin is also effective for masking off-notes, and adds the benefit of a prebiotic fiber to the product it enhances. "Inulin adds a very selective prebiotic dietary fiber to products in addition to making those products be perceived as their whole-fat, full-sugar counterparts," he said. "You don't lose taste quality, and in many cases, you increase taste quality by masking some of the off-notes like soybean aftertaste. Inulin does an excellent job of masking or enhancing the attributes to suppress the soybean aftertaste. Suppressing the high-intensity sweetener aftertaste is really important to make sugar-free products."

Because inulin is not sweet enough to be used as a sole sweetener, it is a good candidate for combining with nonnutritive sweeteners. "The high-intensity sweeteners are used typically with non-caloric sweeteners like high-fiber bulking agents," Tungland said. "Inulin doesn't add a lot of sweetness, but it has mouthfeel effects and some browning effects. But because bulking agents are not really sweet by themselves, manufacturers can pick up the sweetness with a high-intensity sweetener."

In addition to adding mouthfeel and browning effects, sweet bulking agents can also serve to mask off-notes. Inulin and FOS, for example, are often used in combination with high-intensity sweeteners to mask the characteristic metallic off-notes. "The biggest problem with high-intensity sweeteners is they have a bitter or metallic aftertaste," Tungland said. "You typically try to mask some of those effects with the bulking agents you choose. Inulin, by example, and FOS do an excellent job of reducing the high-intensity aftertaste. When you develop a system with inulin and a high-intensity sweetener, it performs more like a true sugar, but extremely low-calorie."

Inulin and FOS also improve viscosity and mouthfeel, are highly soluble and a good fiber source, can be used in sugar-free applications, and affect appetite control, blood lipids, lower cholesterol and triglycerides, and positively affect blood glucose.

Jim Kappas, director of sales and marketing at Cargill Health & Food Technologies in Minneapolis, noted inulin adds bulk to a product while reducing the total calorie content, and it may help boost calcium absorption.

One consideration that has to be kept in mind when using inulin is the prebiotic does not work well with acidic products. "For beverage applications, the main factor to be aware of is that at a very low pH, inulin converts to fructose," Kappas said. "It hydrolyzes to fructose and does not maintain its low-calorie and fiber properties, and tends to be used more in systems about 3.8 pH."

Like inulin, trehalose--another sweet carbohydrate--positively affects blood glucose levels. "Trehalose is a newly available carbohydrate that helps maintain low insulin response as compared with glucose," Kappas said. "It's about half as sweet as sucrose, so manufacturers don't really use it for its sweetness alone. The two key properties in trehalose that make it interesting are 1) metabolically, it has a very low insulin response compared with glucose, and 2) physically, trehalose works as a functional sweetener to stabilize proteins."

According to Kappas, trehalose adds sensory properties to food and beverage products and has a very "clean sweetness," which is milder than sucrose or fructose. It's also less soluble than sucrose by about two-thirds.

The GRAS Issue

One of the biggest issues with food additives is GRAS (generally recognized as safe) status, as determined by the Food and Drug Administration (FDA). While not all sweeteners are GRAS for use in food and beverage applications, some are approved as general purpose sweeteners.

Sucralose, for example, is an approved general purpose sweetener, although it is not GRAS, according to Merkel. "The lack of GRAS approval does not limit the use of sucralose in products, unless a manufacturer has a policy of not using a material unless it is GRAS," Merkel said. "Since it is extremely difficult to make products that are entirely GRAS, reduced in sugar or sugar-free and taste good, I have not seen the lack of GRAS status limit the use of sucralose."

Xylitol is another example of a sweetener that does not have GRAS status, but is approved for use as a sweetener. Xylitol has been fully assessed by FDA and approved for use in food since 1963, according to Meincke. "GRAS is only one form of regulatory approval, and there are many levels of GRAS approvals that can be applied," he said. "But GRAS does not necessarily mean a food or ingredient has been reviewed by FDA."

One high-intensity sweetener not approved for use in food or beverage products in the United States is stevia, an all-natural, high-intensity, nonnutritive sweetener. The plant-derived sweetener has been through the ringer in the United States, with FDA refusing to approve its GRAS status for food or beverage applications. In fact, FDA labeled stevia as an "unsafe food additive" back in the 1980s and has not reversed this decision, although with the passage of the Dietary Supplement Health and Education Act (DSHEA), stevia can be marketed as a dietary supplement.

Several energy beverages and bars are marketed and labeled as dietary supplements, and as such are allowed to contain stevia, or derivatives of stevia. Stevia contains eight glycosides (sugars), one of which is Rebaudioside-A. Honolulu's Sweet Aloha Farms is currently compiling research and scientific data in its application to FDA for GRAS status--specifically for the company's Rebaudioside-A product, SoooLite!, which is a nonnutritive, high-intensity (350 times sweeter than sugar) sweetener. While the glycoside is not approved GRAS at this point, like stevia it can be used as a dietary supplement under DSHEA.

"In the U.S. natural products market, when SoooLite! is used as a supplement, manufacturers can make the claim of 'all-natural' and, on top of that, there is some functionality," said Marty Parisien, vice president of Sweet Aloha Farms. "Rebaudioside-A is proven to reduce blood sugar levels and the data does substantiate claims that it reduces blood pressure levels."

In addition to its functional benefits, Rebaudioside-A is particularly attractive for natural products applications because it is all-natural, according to Parisien. And, he noted, Rebaudioside-A has a wide range of applications. Because it is heat-stable (it has been tested up to 150 degrees Celcius), it is a good match for baking applications, and because of its lingering sweetness profile, it is good for gum, as well. Rebaudioside-A is also pH-stable, and is well-suited for carbonated beverages, alcohol-type applications and as a flavor enhancer. "Aspartame breaks down with cinnamon or cherry or vanilla, and loses its sweetness very rapidly," Parisien said. "Rebaudioside-A doesn't. So, many flavor houses are looking at using it along with cinnamon because some of the chemical sweeteners can't be used in that arena."

Especially in the case of non-GRAS ingredients, manufacturers should be cognizant of labeling details, according to Parisien, to remain in compliance with FDA and improve the industry's image. "The supplement industry in the United States as a whole needs to do a better job of self-regulation," Parisien said. "Right now, there are a lot of very bad claims being made. Instead of giving the industry a bad name through bad press and FDA recalls, the industry should regulate itself. And that's what we're doing. We're ensuring that we have a product and a company and a brand that are associated with the highest integrity, research and quality."