Sugar, and many of its related sweetening, caloric carbohydrates, is being shunned by consumers in efforts to pursue a health-and-wellness lifestyle. According to the 2007 IFIC Foundation Food and Health Survey, sponsored by the International Food Information Council (IFIC), Washington, DC, and conducted by Cogent Research, Cambridge, MA, more Americans in 2007 than in 2006 were concerned with the types of carbohydrates they consume (52% vs. 47%). Specifically, in 2007, 70% of Americans reported being "somewhat or extremely concerned" with the amount of sugar that they consume, compared with 63% in 2006.
Formulating some or all of the sugar out of baked products can be challenging because sugar assumes varying roles besides contributing sweetness. Other functions of sugar include providing bulk, enhancing other flavors and contributing a golden brown crust through the Maillard reaction. In high-heat applications sugar can also caramelize, and in some baked foods such as cookies and crackers, sugar contributes to crunch and crispness. Because of these many critical functions, bakers cannot simply replace sugar with a different sweetener.
SWEETENER INTENSITY. No- and low-calorie sugar replacements are typically characterized as either nonnutritive or nutritive alternative sweeteners, respectively, with the latter less challenging to work into formulations. Here’s why.
Nonnutritive sweeteners, also referred to as high-intensity sweeteners, cover a broad range of sweetening strengths. However, as the name implies, even those on the lower end of the spectrum are still intensely sweet. For example, neotame is 8,000 times sweeter than sugar, while aspartame is about 180 times sweeter. Replacing sugar with either, or a combination of both, requires only a minuscule amount, which means a significant reduction in solids. Thus, when high-intensity sweeteners are used in baked food formulations, it is imperative that bulking agents be added for solids replacement.
Usage levels are so low that the high-intensity sweetener contributes no calories to the finished product. However, calories can come from the bulking agent, thus 100% sugar replacement is not always the most sensible solution.
Some bakers have found that replacing some of the sugar with a high-intensity sweetener is the best approach to lowering calories and reducing sugar content. For example, the same example formula can be modified to contain 25% less sugar by replacing 2.5 g sugar with 0.0002 g neotame. Such a reduction in solids is often invisible in the application or readily supplemented.
Keeping some sugar in the formulation also allows important reactions to take place. As mentioned, when sugar is heated to a sufficiently high temperature, it decomposes or caramelizes. Its color changes first to yellow then to brown, and it develops a distinctive and appealing flavor and aroma. Crust color is also produced in baking when sugars and proteins interact in what is known as the Maillard reaction.
In yeast-leavened products, it is important to keep some sugar in the formulation because the sugar acts as food for the yeast cells in the natural process of fermentation. When the yeast consumes the sugar, carbon dioxide gas is produced and makes the dough rise.
Other high-intensity sweeteners can be used in baked foods, alone or in some combination, with or without a bulking agent. For example, there’s sucralose, which is 600 times sweeter than sugar; saccharin, which is 300 times sweeter than sugar; and acesulfame-potassium, which is about 200 sweeter than sugar.
BULK WITH CALORIES. Replacing sugar with nutritive alternative sweeteners alleviates some, or all, of the solids-reduction issues because their usage levels are similar to sugar, if not a direct replacement. Certain nutritive alternative sweeteners have additional benefits that make them attractive to different demographic segments. Although these sweeteners contribute calories and carbohydrates, they are not classified as sugars by the Food and Drug Administration.
For example, tagatose has a physical bulk similar to sugar and is almost as sweet but only contributes 1.5 Cal per g, compared with sugar’s 4 Cal per g. Further, tagatose is metabolized differently, has a minimal effect on blood glucose and insulin levels and provides a prebiotic effect.
The processing and preparing of foods made with tagatose must accommodate certain temperature reactivities because tagatose-containing products brown and caramelize more readily than sugar-containing baked foods. In certain applications and under controlled conditions, this can be very desirable.
For example, added at up to 2% in muffins, tagatose contributes to nice crumb development and rich, toffee flavor. If added at a level of 0.5% to 1.0% in bread, toasting time is cut in half, and a nice, homogeneous color will develop in the toasted bread. Tagatose also has application in frostings and icings because it maintains sweetness but has only a minimal effect on blood glucose levels. This is desirable for products intended for diabetics.
Tagatose is made via a patented procedure from lactose (milk sugar) in a 2-step process. In the first step, lactose is hydrolyzed to glucose and galactose. In the second step, galactose is isomerized to D-tagatose by adding calcium hydroxide. D-tagatose is then further purified by means of demineralization and chromatography. The final product is a white crystalline substance that is greater than 99% pure.
Tagatose is attracting the attention of bakers because it creates unique opportunities to develop products for the burgeoning health-and-wellness marketplace. Only 15% to 20% of tagatose is absorbed in the small intestine. The major part of ingested tagatose is fermented in the colon by indigenous microflora. This prebiotic effect has been proven through clinical research, which has shown an increase of good bacteria in the large intestine and colon after consumption. Tagatose selectively promotes the production of butyrate and lactic acid bacteria, which are essential to maintain a healthy digestive system. Like dietary fibers, tagatose is broken down by the gut bacteria to short-chain fatty acids, which decrease acidity in the large intestine and are recognized as beneficial for a healthy epithelium in the large intestine. The unique combination of sweetness with the prebiotic effect enables creation of great-tasting, better-for-you baked foods.
Trehalose is another low-calorie, nutritive sweetener. It is found naturally in an array of products including honey, mushrooms, lobster, shrimp and foods produced using bakers and brewers yeast. The commercial product is made from starch by an enzymatic process. Trehalose is only 45% as sweet as sugar; thus, it is seldom used as a direct replacement for sugar. However, it can be added for flavor enhancement, sweetness optimization, texture development and crystallization inhibition.
The latter is key in high-moisture baked foods that are distributed frozen because trehalose protects and preserves cell structure. It may aid in the freezing and thawing process by assisting in the maintenance of the desired texture of the food. It is also heat stable.
Trehalose is fully caloric and after ingestion is broken down in the body to glucose, but with an even blood glucose response, making it ideally suited for products formulated to provide a natural, consistent source of energy.
POLYOLS. Isomalt is a sugar replacer consisting of disaccharide alcohols. Derived exclusively from sugar, isolmalt is manufactured in a 2-stage process in which sugar is first transformed into isomaltulose, followed by hydrogenation using a metal catalyst.
Isomalt has only half the calories of sugar because the human body can only use 50% of its energy. It has very low hygroscopicity and can directly replace all of the sugar in applications such as cookies, hard biscuits and creme-like wafers in a 1:1 ratio. Even if sugar is only partially replaced, biscuits and cookies made with isomalt will absorb only a negligible amount of water during storage, keeping them fresh and crisp. The sweetening effect of isomalt and its minimal hygroscopicity are a plus for baking mixes, allowing improved powder flow.
Isomalt belongs to the category of nutritive sweeteners known as sugar alcohols or polyols. Polyols are neither sugar nor alcohol. They are carbohydrates with a chemical structure that partially resembles a sugar and partially resembles an alcohol. These nutritive alternative sweeteners are incompletely absorbed and metabolized by the body and consequently contribute fewer calories than sugars. Because of their incomplete absorption, polyols produce a lower glycemic response than sugar or glucose and are often used in the formulation of products for diabetics.
There are a variety of polyols with baked food applications. In addition to isomalt, sorbitol provides sweetness as well as functions as a humectant and texturizing agent, thus preventing baked foods from drying. This helps maintain their initial freshness during storage.
Sorbitol is about 60% as sweet as sugar with one-third fewer calories. It is stable and chemically unreactive, thus it can withstand the high temperatures encountered in the oven. It also does not participate in the Maillard reaction and, thus, is often used in the production of cookies where a fresh color with no appearance of browning is desired.
The polyol gaining attention among many manufacturers is erythritol because it is considered all natural and, thus, is the only alternative sweetener accepted by the natural foods industry.
The news gets even better. At 0.2 Cal per g, erythritol is virtually noncaloric — something only highintensity sweeteners can claim. It is a white crystalline powder that flows easily because of its its nonhygroscopic character. With about 70% the sweetness of sugar, erythritol has a clean sweet taste that is similar to sugar. It has excellent heat stability and has been shown to improve baking stability and the shelf life by managing water activity.
Erythritol is rapidly absorbed in the small intestine and eliminated by the body within 24 hours; thus, the laxative side effects sometimes associated with excessive polyol consumption are unlikely when consuming erythritol-containing foods.
Because of its reduced sweetness, erythritol is often used in combination with high-intensity sweeteners. It has been shown to work synergistically with aspartame and acesulfame potassium, resulting in a sweetener combination that is sweeter than the sum of the components, with an improved taste profile and economic and stability advantages.
Regardless of the approach a baker takes to replace sugar, the process is complex and requires a great deal of trial and error. Oftentimes, the best approach is to replace sugar with multiple alternative sweeteners.