Fiber for the future
June 1, 2014
by Mari Rydings
Consumer interest in healthy eating and clean labels, coupled with the 2010 Dietary Guidelines for Americans report that identified fiber as one of four “nutrients for concern,” have catapulted this essential health component to the forefront of baking and snack formulating.
The Food and Drug Administration (FDA) considers Adequate Intake (AI) of fiber to be 25 g per day for women and 38 g per day for men. Yet multiple research studies have shown that most Americans are nowhere close to reaching their Recommended Daily Intake (RDI) of fiber. For baked goods and snack food formulators, plenty of opportunity exists to use cereal grain fibers to help consumers bridge this gap without sacrificing food’s organoleptic qualities.
Intrinsic fiber and added fiber are the two main fiber categories: intrinsic (naturally present and intact in foods) and added (chemically extracted and then added to food). While debate over the nutritional labeling of intrinsic and added fibers continues, food manufacturers frequently add either or both forms to products to boost dietary fiber content and make nutrient claims.
“There is no study showing whether intrinsic or added fiber is a better choice,” said Jie Hu, senior research scientist, Horizon Milling, Wayzata, MN. “Although reports on synergistic effects of fiber and other biologically active components can be found, you cannot generalize this conclusion. Due to the fact that less than 10% of the US population meets the recommended fiber intakes, the amount of total fiber is of more concern than the tiny differences between intrinsic and added fiber.”
What’s more, getting all that recommended fiber into the daily diet absolutely requires supplementation. “Intrinsic fiber in most food forms is at a level that makes it challenging for the average American to reach the RDI for fiber,” said Jenn White, food industry specialist, Brenntag Mid-South, St. Louis. “Few foods in the categories suggested as natural sources — fruits, vegetables, grains and legumes — qualify as ‘good’ or ‘excellent’ sources of fiber levels based on FDA labeling requirements. Adding fiber as a functional ingredient to such foods is a viable solution.”
For the most part, cereal grain fibers are extremely compatible with normal bakery formulas and are commonly used in applications such as cereals, snacks, cookies, buns and cakes. Yet formulating with them can be a bit tricky because each type brings its own characteristics and fiber content to the mix. In other words, one size does not fit all. In the grain group, barley, wheat and rye offer the highest fiber content, ranging from approximately 11% for wheat to 17% for barley. The fiber content range of corn and sorghum is 6 to 9%, while whole grain rice has a 3 to 4% fiber content level.
Depending on the amount and type of fiber that will be used, it’s possible that bakers will need to adjust their formulas. “When formulating with whole grain flours, proper absorption and hydration is critical because of the effect fiber can have,” said Elizabeth Arndt, PhD, director of R&D, Ardent Mills, Omaha, NE. “Different whole grains vary in their level and rate of absorption. One of the common problems we see in making whole grain and multigrain dough is the failure to add enough water.” Dr. Arndt also emphasized monitoring mix time because whole grain and multigrain doughs typically require less time than refined wheat flour dough.
When selecting a cereal grain fiber, product developers must also factor in what functionality they want to achieve with the final product. This ensures they choose the appropriate fiber for their applications. “Different options will vary on the level of refinement, fiber content and fiber length as well as their oil and water absorption capabilities,” noted Aida Prenzno, director of technology at Tucson, AZ-based Gum Technology, a business unit of Penford Food Ingredients. “For example, oat fibers are widely used in bakery applications, and they are available in a variety of choices. If you choose an oat fiber with high water absorption, you may need to adjust your formula.”
In addition to altering water-holding capacities, cereal grain fibers can also affect dough structure. “Fiber ingredients compete with bread flour for water absorption and interfere with gluten’s role in structuring and gas retention, causing a reduced loaf volume and a tacky crumb texture,” Horizon Milling’s Ms. Hu added. “We suggest adding more water to compensate along with vital wheat gluten for volume re-building.”
The size of the fiber particles impacts dough structure, too. Cereal grain fibers are a natural part of grains, and they reside in the bran and germ parts of the seeds. According to Michael Weibel, vice-president, R&D, Watson, Inc., West Haven, CT, bran particles are sharp and can wreak havoc during processing. “The sharp particles penetrate the gas bubbles during leavening,” he explained. “When that happens, the gas cell structure of the dough begins to collapse. That’s why whole wheat products are typically more dense. However, we are seeing improvement in this area because whole grain bran particles are being ground finer, resulting in dough products that have fine grain and less dense texture.”
Addressing texture, color, taste
Perhaps the biggest challenge is the need to develop products that meet consumer expectations for taste, texture and visual appeal. Adding cereal grain fiber beyond 10 to 20% can make that difficult.
“Browning can be an issue, although this is less of a problem in corn-based foods where textures are generally short to begin with,” noted Todd Giesfeldt, mill R&D senior manager, Didion Milling, Cambria, WI. “As the amount of cereal fiber in baked goods increases, organoleptic properties, apart from texture, are adversely affected, resulting in a pasty or gritty taste. It’s at this point the taste attributes of the fiber itself start to come through.”
As a solution to this potential problem, Atchison, KS-based MGP Ingredients developed resistant wheat starch, which can be used as a 1:1 replacement for flour in baked foods. “This resistant starch is white in color, making it an ideal source of ‘invisible’ fiber,” explained Liming Cai, PhD, an MGP applications scientist. “It does not detract from the appearance of bakery products, which makes it perfectly suitable for white bread, cake and other flour-based applications.” Dr. Cai added that the resistant starch’s small particle size imparts a smooth, non-gritty texture in food products and requires little or no formulation changes in terms of water absorption or mixing and baking time.
Essentially, consumers want to have their added-fiber cake, cookies, bread and snacks and eat them, too. “Consumers want baked foods and snacks with added fiber, but they want them to taste the same as they always have,” observed Kornelija Matkovic, PhD, principal scientist and project manager, applications, SunOpta, Edina, MN. “We work with product developers to find the best way to incorporate fiber into their products to achieve desirable sensory characteristics.”
According to Courtney Kingery, senior product manager, fibers, Tate & Lyle, Hoffman Estates, IL, the company’s soluble corn fiber product enables manufacturers to supplement intrinsic fiber in a variety of applications without negatively impacting consumers’ digestive tolerance or altering the food’s taste, color or texture.
“This soluble corn fiber also has high solubility, low viscosity and stability in low-pH environments,” she said. “It also enables manufacturers to add fiber with a clean-label solution.”
With so many varieties and functionalities, how can bakers and snack food manufacturers make sure they are on the right track? According to Rajen Mehta, PhD, senior director, specialty ingredients, Grain Millers, Eugene, OR, product developers should first map out their goals and objectives in terms of what they want to achieve with fiber formulation.
“Once you have your target clearly defined, articulate it to your supplier. They can guide you to the proper type of fiber and usage ratios, which will help create a formula to meet your goals.” Dr. Mehta said that customers, by selecting the right fibers, instead of listing three or four sources of fiber will be able to list only one or two.
Going gluten-free with fiber
The low fiber content of most gluten-free foods makes adding fiber necessary to build a complete nutrition profile for such baked goods and snacks. Yet incorporating cereal grain fiber into gluten-free formulas does not come without difficulties.
“It’s challenging because there isn’t any gluten, and structure within the dough system is required to carry the weight of the fiber,” explained Susan Kay, manager, product applications, Bay State Milling, Quincy, MA. “Using fiber in gluten-free products requires formula changes. You may have to incorporate or increase the gum system, non-gluten proteins or other structure-building sources to meet this challenge.”
Water absorption presents one common formulating challenge. “Water compensation is the first adjustment of a formulation,” Ms. Hu explained. “Starch gelatinization increases the viscosity of the dough or batter so the foam structure can be stabilized and the crumb can be fixed. Fiber may affect starch gelatinization by delaying its onset temperature and prolonging the baking time as a result.”
Staling through starch retrogradation poses another issue, one that fiber potentially ameliorates. “Fiber can affect bread firming in two ways: either by interfering with amylase rearrangement or by changing water migration in crumb during storage due to fiber’s water-binding capacity,” Ms. Hu said.
Keeping these challenges in mind, typical non-gluten cereal grain fiber options include potato flour, rice flour, oat fiber, sorghum flour and corn fiber, all of which are compatible with gluten-free recipes when formulated correctly.
For example, SunOpta offers a rice fiber that contributes more than 90% fiber and imparts a bland flavor and fine, silky mouthfeel to products such as cereals, nutrition bars and bakery mixes. “We see the biggest application for this rice fiber in the baked foods and snacks industries is gluten-free,” noted Cathy Peterson, a SunOpta food science nutrition specialist. “It is a good fit for enriching bakery products and to increase the fiber content of rice snacks, too.”
The fiber content of gluten-free whole grain flours made from ancient grains such as sorghum, quinoa, amaranth, teff and buckwheat ranges from 6 to 10% and can naturally increase the total fiber quotient of gluten-free flour blends.
“Sorghum flour is a great cereal grain fiber for gluten-free applications,” said Brook Carson, director of R&D, ADM Milling, Overland Park, KS. “ADM supplies white sorghum flour and whole grain white sorghum flour for whole grain, multigrain and gluten-free applications. It also works well in cereal applications because it has a clean flavor profile and a crisp texture without being too fragile.”
The renewed focus on fiber is not going away, which is good news for the baking and snack industries, because it means the potential for new product applications using cereal grain fibers.
From Colleen Zammer’s viewpoint as the director of product marketing for Bay State Milling, no application is off limits. “Historically, products with added fiber did not taste good, and people still tend to shy away from foods promoting it,” she said. “However, if you use the term ‘whole grain,’ that imparts a more holistic idea that people positively identify with.”
Today, a significant portion of new product development is focused on the gluten-free category. “Gluten-free is an area driving the need for cereal grain fibers to improve the nutritional profile and shelf-life of gluten-free food products,” offered Bryan Scherer, vice-president, R&D, Penford Food Ingredients, Centennial, CO. “Depending on the cereal grain fiber, it could be used to replace higher caloric content such as flour and/or sugar in baked goods and snack products.”
Ardent Mills’ Dr. Arndt noted more opportunities to use alternative cereal grains in extruded applications, gluten-free foods and snacks. In addition, their functionality as thickeners in fruit-based fillings allows formulators to put whole grain fiber into unexpected parts of the finished product.
She said the company offers a fiber ingredient produced from waxy, hulless barley that is high in both beta-glucan and overall dietary fiber when compared with traditional food barley and other grains. “It has more than three times the total and soluble dietary fiber compared with oats and 10 times the fiber of brown rice,” Dr. Arndt said. “It also has about half the starch compared with most other grains, making it a unique option to boost the fiber content baked foods and snacks.”
When considering the benefits of very finely milled cereal fiber, Watson, Inc. developed proprietary milling equipment capable of micronizing cereal by-products, which can then be used for human consumption.
“We use bran-based products such as rice, oats, corn and wheat and mill them to under 10 microns, making the particle size quite small,” Mr. Weibel explained. “The smaller the particle size, the more bioavailable the micronutrients become. Further, they are organoleptically invisible. The micronized by-product particles can be recombined with refined flours to make terrific breads. We’ve had interest from pasta makers and conventional bread and roll bakers who have found that use of these fractions have significantly improved their existing products and provided new product opportunities.”
Down the road
As consumers and regulators alike continue their demand for an increase in the fiber content of food, manufacturers can expect to see changes ranging from sources to technology to processing to shape and size.
SunOpta’s Ms. Peterson predicted the industry will see a broader range of fibers from different sources as well as significant progress in the technology used to modify the shape and particle size so it is easier to work with.
“SunOpta is looking at ways to make fiber smoother, longer or finer for easier incorporation into products,” Ms. Peterson said. “The company is also looking at how processing fiber can affect its water-holding properties. We are able to drill into the specifics, such as the level of water-holding, particle size and texture, that are needed for specific applications.”
Other fiber suppliers projected a proliferation of new cereal grains containing intrinsic fiber, driven by the push for clean labels.
“A lot of work is being done to improve the fiber content and functionality through conventional seed breeding techniques,” Ms. Zammer said. “I think we’ll see more work at the seed genetics level and the creation of more naturally occurring fibers that are intrinsically functional and healthful.”
Clean label was cited by Jennifer Stephens, marketing manager, Penford Food Ingredients, for the increasing popularity of grain-based fibers. “Botanical sources such as rice, sorghum, millet, barley, buckwheat and quinoa are riding the ancient grain wave and being promoted not only for their protein and nutritional content but fiber as well,” she noted. “Clean label has created a need for natural cereal grains that are easy to use.”
Brenntag’s Ms. White agreed that exotic grains are becoming more mainstream but thought that the limited supply of these grains might make product launches unrealistic for major manufacturers. “We may see some new items listing fiber from sources like buckwheat, amaranth or quinoa coming from smaller companies,” she predicted.
When it comes to corn fiber, Mr. Giesfeldt described this ingredient functioning as a fat mimetic, especially if suppliers can meet the technical challenge of grinding it to under 1 or 2 microns. He also pointed out another area with potential: corn fiber gum. “The process can also yield relatively pure cellulose, which could be more label-friendly than other sources of food-grade cellulose,” he observed.
As regulators and manufacturers work to fill the nutritional fiber gap, supplier offerings in this area should expand rapidly, making it easier for bakeries and snack food producers to help consumers get their added-fiber cake and eat it, too.