February 01, 2009
by Laurie Gorton
With America’s rates of obesity and diabetes climbing, consumer interest in low- and no-sugar foods is taking off. "We are seeing trends among food processors for more replacement of sucrose in baked foods," said Judy Turner, manager of food applications, Tate & Lyle (Americas), Decatur, IL. "We receive a lot of customer requests on this subject."
While consumers view such products as health-and-wellness offerings, bakers have a different outlook, one defined by formulating and processing needs. It’s all well and good to cut out sugar, but, they ask, how can sugar’s "other" functions be replaced? The structure, color and texture of the finished baked food are just as important, and maybe more so, as its sweetness.
TECHNICALLY SPEAKING. Replacing sugar is no easy task. Take the matter of solids, which sugar contributes to doughs and batters, thus aiding the structure and body of the finished products. "Most other solids (that could take the place of sugar) do not have similar physical properties, nor do they influence the physical properties of a system like sucrose," explained Scott Helstad, technical services manager, Cargill Corn Milling North America, Wayzata, MN. (In the context of this article, the term "sugar" refers to sucrose, not invert or corn syrups.)
Solids contributed by sugar also help control water activity, and Mr. Helstad continued, "Sucrose influences the water activity of a final product to make it shelf-stable and to control moisture migration within the product and within ingredients. Hygroscopicity and humectancy are also influenced and will need adjusting as the sucrose is displaced by ‘other’ ingredients."
The bulk contributed by sucrose means that "formulators need to be mindful that they pay attention to replacement of total solids in the formulation and of molecular weight," said Ronald C. Deis, Ph.D., vice-president, applications research and technical services, Corn Products Specialty Ingredients, Newark, DE. "Higher-molecular-weight polymers used as replacements affect starch gelatinization temperature, protein denaturation, viscosity, water activity, specific gravity, freezing characteristics and many other characteristics differently than sucrose in baking applications.
"Something like a maltitol syrup or maltitol solution can replace sucrose in a bakery application if the formulator accounts for the added water contributed by these ingredients," Dr. Deis continued. The higher-molecular-weight ingredients delay starch gelatinization, increase cookie spread or decrease cake volume. Lower-molecular-weight materials cause starch to gelatinize earlier, decrease cookie spread or cause cakes to collapse.
"Molecular weight can be balanced," he explained, "by using more than one replacer or a performance system designed for the application."
Sucrose influences the gelation of starch from flour or other added starches. "This affects the height and spread (of cookies)," Ms. Turner observed. "This function is based on the interaction between the sweetener and the starch."
Volume, rise and density are also affected. "And changes in these features can impact packaging and consumer acceptance," Mr. Helstad said.
Appearance — crust color, browning, crumb density and texture — can also be affected. For example, he explained, textural features like softness, chewiness and crispiness are influenced by sucrose’s crystallinity and solubility and must be adjusted when it is replaced. "Is the bite crisp or chewy?" he asked. "Is the surface appearance glossy, frosted or matte? Does the final product need to have a ‘grained’ or ‘ungrained’ texture? These properties of sucrose help determine a final product’s texture and bite. Sucrose solubility and crystal size can impact the viscosity of a batter, which will impact batter density and final product density."
Crust color improves the look of cake and cookie tops, and any nutritive sweetener that is also a reducing sugar accomplishes this result through the Maillard reaction. "Fructose, for example, will add color to crusts," Ms. Turner said.
And then there is the matter of sweetness. Corn syrups provide a broad array of nutritive alternatives to sugar. In combination with neutral-flavored bulking agents such as polydextrose or soluble corn fiber, high-intensity sweeteners can substitute for sugar’s sweetness, if formulators take into account dough and batter pH and baking temperatures. "Sweetness also influences flavors and may mask bitter off-notes," Mr. Helstad added.
CHOICE OF INGREDIENTS. "Sucrose has four basic functionalities — sweetener, bulking agent, texturizer and as a source of crust color — and its replacements reflect these," Ms. Turner said. For example, Tate & Lyle not only manufacturers sweetener syrups but also Promitor soluble corn fiber and Stalite polydextrose, which have bulking functions yet low caloric values. The supplier also produces Splenda non-nutritive sweetener, which is 600 times sweeter than sucrose but with no calories, and Crystar crystalline fructose, which because it is sweeter than sucrose can be blended with sugar to retain overall sweetness but yield lower sugar content overall.
"One of Promitor soluble corn fiber’s benefits is that it is so easy to use," Ms. Turner said. "It has almost the same consistency as corn syrup. Most replacements are 1:1 in commercial applications. It is very low in sweetness and flavor, so the formulator would have to add Splenda to restore the sweetness."
Bulking agents include polydextrose, which also acts as a prebiotic. "Caloric reduction occurs because Litesse polydextrose has an energy value of 1 Cal per g, compared with fat at 9 Cal per g and sugar at 4 Cal per g," said Peter Thomson, application manager, bakery & cereals, sweeteners division, Danisco (UK) Ltd., Redhill, UK. "Litesse is only partially fermented by intestinal micro-organisms, producing volatile fatty acids that are absorbed and used by the body." The prebiotic qualities of this polydextrose are considered beneficial in many countries, he noted.
Sugar alcohols, also called polyols, are produced by the catalytic hydrogenation of various saccharides. For example, lactitol is produced from lactose and xylitol from xylose. Polyols’ properties such as viscosity in solution and their effect on boiling and freezing points of water depend upon their saccharide source and molecular weight.
Many polyols are found in nature but are expensive to extract. Their hydrogenated form makes them difficult to digest and absorb, thus lowering their caloric content. They lower the glycemic index of foods, making them suitable for diabetics. "In Europe, (polyols) have all been assigned a value of 2.4 Cal per g, and in the US, lactitol is 2 Cal per g and xylitol 2.4 Cal per g," Mr. Thomson stated.
For example, lactitol has a sweetness of approximately 40% that of sucrose, requiring use of a high-intensity sweetener to replace sugar’s sweetening power, but products made with lactitol generally have similar eating characteristics to those made with sucrose. It is not hygroscopic, so it can be used to maintain the crispness of baked foods such as cookies.
Maltitol is one of the most widely used sugar replacers, according to Carl Jaundoo, PhD, senior applications specialist, Roquette America, Inc., Keokuk, IA. It acts as a bulk sugar replacer. "Among the key considerations are the balance of solids, sweetness and physical attributes such as granulation," he continued. "Sugar replacers such as maltitol are available in different granulations and can be used to replace baker’s sugar and powdered sugar in icings and creme fillings."
Tim Bauer, NA polyols and dextrose product line manager, Cargill Health & Nutrition, confirmed maltitol’s value in bakery formulas, noting that its sweetness is very similar to sugar. "It requires very little modification to formulas, and baking performance is the closest to sugar," he added.
Another polyol of interest is erythritol. "Zerose erythritol is the only 0-cal polyol," he continued. "It has great sugar-like taste, excellent heat stability, improved baking stability and shelf life and water activity management." Cargill’s proprietary production process for erythritol allows it to be considered natural, and a USDA-certified-organic style is available.
Corn syrups are more conventional sucrose replacers, and companies provide them in a broad range of sweetness ratings. As explained by Mr. Helstad, the Cargill portfolio includes both 42% and 55% Isoclear high-fructose corn syrup, Clearsweet 95% liquid dextrose and a variety of Clearsweet corn sweeteners ranging from 43 to 63 DE, as well as Clearsweet 43% and Satin Sweet 65% high-maltose corn syrups.
MAKING IT WORK. Replacing sucrose can be either quite easy or relatively complex, depending on the desired effects in the finished product. "While most sugar replacers provide sweetness, the choice of sugar replacer is related to the finished product characteristics," Dr. Jaundoo said. Maltitol, for example, gives a sweetness almost identical to sugar, but where humectancy is desired, sorbitol would be preferred, and maltitol syrups add to a chewy mouthfeel.
"With such a wide availability of sugar replacers, it is possible to create sugar-free, reduced-sugar or no-added-sugar products with the same taste and texture of the sugar products by using a combination of the different sugar replacers," Dr. Jaundoo said.
Debra Bryant, director, business development and technical services, BENEO-Palatinit, Inc., Morris Plains, NJ, explained use of Isomalt, a low-calorie sweetener produced by hydrogenating isomaltulose. "With Isomalt, which provides a 1:1 replacement of sugar, there really aren’t any significant technical issues to overcome," she observed. "Standard production parameters for sugar may be applied with Isomalt for most baking applications. Differences can occur in the dough preparation, depending on the recipe." Such modifications are normally limited to choosing the right granulation, the amount of water used and the mixing time.
Isomalt differs from other polyols because it does not provide any atypical cooling effect in bakery foods. "Because it has very low hygroscopicity, Isomalt provides outstanding shelf-life properties in its main baking applications, cookies and hard biscuits," Ms. Bryant continued.
Crystalline sorbitol, another polyol, can be used in cremes or fillings, noted Dr. Deis, and Corn Products Specialty Ingredients (formerly SPI Polyols) recently introduced crystalline erythritol, which crystallizes well in fondants and marshmallow. "For replacement of syrups, we have a line of maltitol syrups and polyglycitols designed to replace the sweetness and molecular weight distribution of corn syrups," Dr. Deis added.
"In most bakery applications," he continued, "it is best to keep total solids in a formulation the same — minimizing moisture changes from a sucrose type formulation. Many times, this just means taking some of the water out of the original formulation."
Formulators should seek sucrose replacers with attributes most similar to sucrose or the syrup being replaced, but they should also remember that these low-digestible carbohydrates must not be overused in formulations, Dr. Deis cautioned. "For polyols, a general rule of thumb is not to exceed 15 g per serving, which takes into account potential overconsumption by the consumer." Of all the polyols, maltitol has better gastrointestinal tolerance.
When considering no-added-sugar cakes, Mr. Thomson suggested starting with replacing all the sucrose with a blend of 25% Litesse polydestrose and 75% lacitol plus a high-intensity sweetener to adjust the sweetness profile. "This will, in most cases, achieve the same texture, volume and flavor as a standard full-sucrose version," he said.
Some sugar replacers are easier to use than others, Ms. Turner pointed out. "Sucrose has a small molecular weight, while some replacers are larger in size and, thus, give more viscosity to the system," she said. "Soluble corn fiber and polydextrose tend to be lower in molecular weight than inulin and other sweetener replacers. And with polyols, you get into the tolerance issue. Corn fiber and polydextrose are well tolerated."
The newest sweetener alternative is Reb-A derived from extracts of stevia plants. Use of Reb-A, a high-intensity sweetener, in baked foods will require bulking agents. "The issues caused by removing sugar can be resolved through adding some other ingredients besides stevia-derived sweeteners such as PureVia Reb-A," said Jordi Ferre, vice-president, general manager, PureCircle USA, Florham Park, NJ, "and formulation/flavor houses are instrumental in supporting our customers’ reformulation needs."
INTO THE FUTURE. "When replacing sugar, the food scientist needs to ask why?" stated Mr. Helstad, who emphasized that at present sugar replacement is not easily done and should be viewed as product specific. "The challenge remains how to replace a very cost-effective and functional ingredient with an equally functional ingredient or ingredients to create a product that still tastes good and does not dramatically increase in price. The company that finds this type of solution for baked foods will unlock a very big market." Until then, he suggested that it may prove to be more efficient to slowly reduce levels and work with other replacers.
"Because serving size weights are greater for baked applications than for many other applications, sugar reduction and caloric reduction are often better objectives than total sugar replacement," Dr. Deis said. Thus, completely eliminating sugar in the diet is not the best goal; a better target would be reducing sugar and calories without impacting texture and taste.
Food manufacturers will continue to launch nutritionally improved products, according to Mr. Thomson, to capture the growing market for reduced-glycemic products.
"With a focus on sugar reduction in the diet by consumers, the development of great-tasting sugar-free, reduced-sugar and no-sugar-added products is one area of growth in a flat or declining bakery market," Dr. Jaundoo said.
This article can also be found in the digital edition of Baking & Snack, Feb. 1, 2009, starting on Page 83. Click here to search that archive.