Fiber du Jour
Fiber exists everywhere. It exists in whole grains and as hydrocolloids, prebiotics and resistant starches. Now that the “fiber gap” in the average American diet has been identified, experts recommend ingesting at least 15g daily of additional fiber; the decision to be made is simply a matter of determining what fiber is most appropriate for what product application.
The first question a manufacturer should ask before determining what fiber to use for nutritional purposes in a food product is, “What health benefit am I trying to sell in this product?” Fiber, in its many forms, is influential at abating and controlling a number of chronic diseases including: high blood cholesterol, diabetes and colon cancer.
The dietary guidelines do not differentiate between soluble fiber and insoluble fiber, but manufacturers will need to understand their benefits and disadvantages. Most people are familiar with insoluble fiber, which is known to provide bulk in stool and assist with maintaining regular eliminations. However, soluble fiber is just as (if not more) important than insoluble fiber for health. Soluble fibers, like beta glucan, which can be found in oats and barley, help lower blood cholesterol levels and control blood sugar.
“Soluble fiber tends to be the more minor fiber in foods, making it tough for consumers to incorporate it in the diet,” says Elizabeth Arndt, manager of product development for a food ingredient company. “Vegetables like okra, known to have higher soluble fiber content, may not be the most popular things to eat.” Deciding on the type of fiber to use is governed by the desirable appearance and texture of the product.
Fever for FiberSome fibers are great for a wide variety of applications, while others can be used only in very specific areas. There are health claims and/or label terminology associated with some forms of fiber and not others. For example, prebiotic properties, laxation and satiety are three qualities that can be referred to on product labels in association with the benefits of fiber.
Oats, a very popular whole-grain fiber source, is well recognized by consumers and heavily saturated in mainstream retail products. Beta-glucan is the predominant soluble fiber in oats and barley, and the two grains have garnered permission to use a USDA health claim stating a relationship between oat and barley soluble fiber and reduced risk of coronary heart disease.
Beta glucan is a very viscous soluble fiber widely associated with cholesterol reduction. It increases viscosity, and delays the emptying of contents from the stomach. It also delays the uptake of certain nutrients, which can have an effect on blood sugar management. “In barley, the ratio of soluble and insoluble [fiber] is more equal, whereas wheat contains mostly insoluble fiber,” explains Arndt. “So, barley provides an easier way to increase the amount of soluble fiber in the diet.” In addition, there are varieties of barley that contain more fiber than other common cereal grains.
For example, Prowashonupana (Prowash) is a non-genetically modified (GMO), “breeder-developed” variety of barley named for its characteristics by participants in a program at Montana State University. It is a high-protein (Pro), waxy (wa) starch, short-awned (sho [description of the structure of the hull that envelopes the kernel]), nude or hulless (nu) barley grain from the parent variety Compana (pana).
“The Prowash barley has approximately half the starch compared to other common cereal grains, including oats, wheat, corn and other barley,” says Arndt. While oats contain 10% dietary fiber and hulless barley has 13%, the Prowash barley variety has a minimum 30% fiber content, of which 12% to 15%) is soluble fiber or beta-glucan. Up to half of the fiber content of typical varieties of oat and barley are beta-glucan. Other grains contain beta glucan in much smaller amounts, adds Arndt.
Barley is highly associated with beef barley soup, where it is used in a pearled form or as a whole kernel; however, since the health claim recently was amended to add barley beta-glucan, it is likely barley food products soon will become a more popular source of fiber for prepared foods.
“Barley is very versatile and can be used across meal occasions: from breakfast to dinner to snacks and in baked goods such as breads, muffins, cookies, cakes and pastas. In products like muffins and cookies where you are not depending on gluten, you can use barley at 100%,” says Arndt.
Barley can be used in side dishes like rice pilaf. For example, 30% replacement of Prowash barley for brown rice allows the “excellent source of fiber” claim. “If you are trying to meet certain nutritional parameters, there are a lot of options by blending in oats or barley,” suggests Arndt.
According to Arndt, the Prowash variety of barley absorbs more water and can help retain moisture. “Barley does not have the same kind of gluten that wheat does. As a result, it is generally used as a partial inclusion in leavened breads.”
Many associate fiber with whole grains. Several studies show that whole grains may lower cholesterol levels in part because of a high level of soluble viscous fiber. Nevertheless, whole grains do not ensure high-fiber content. Wheat, oats, barley and rye are a few whole grains high in fiber.
“When we compare fibers, versus foods that are sources of fibers, there are some important functional and nutritional distinctions,” explains Arndt. “Although isolated fibers are wonderful and have their place in product development, they are just that…isolated. The other nutritional attributes and values have been removed from the original. So, when eating foods such as barley, you get not only the fiber, but also the whole-grain nutritional benefit, the vitamins, minerals, healthy lipids and other phytonutrients. Whole grains are a complex package, and the whole of the whole grain is greater than the sum of its parts. We have not figured out the roles of all of the bioactives, but they are all functioning together.” Some believe fiber integrated into plant cellular structure is handled differently in the body than isolated fiber.
There is a connection between whole grains, weight maintenance and satiety. Whole grains can help increase satiety of foods because they may delay gastric emptying and digest more slowly. Grains such as Prowash barley—with more fiber and less starch—have big potential in this area. The glycemic index (GI) of cereal grains is influenced by how the grain is processed. Grains like Prowash barley, with high fiber and low starch content, generate a much lower glycemic response, delay gastric emptying and also offer less overall starch for digestion, says Arndt.
Prepping PrebioticsPrebiotics support the growth of beneficial microflora in the gut. Some prebiotic ingredients from the chicory root have been shown to promote satiety and to limit energy intake in humans. For example, oligofructose fermentation modulates the release of gut hormones in the blood, which act as signaling agents to the brain, influencing appetite and, ultimately, food intake, says Joe O'Neill, a national sales manager with an inulin supplier.
Oligofructose, a mixed fructo-oligosaccharide (FOS), is the enzymatic hydrolysis product of inulin. It consists of mixed glucose and fructose-terminated chains, varying in length from 2 to 7.
“Oligofructose is a pleasantly sweet hydrolysis product of native inulin,” says Coni Francis, PhD, RD, a spokesperson at a company that sells FOS. “It consists of mostly linked fructose units, with some glucose-terminated chains. The unbound fructose chains have been shown by science to have prebiotic properties, and impart the ability of oligofructose to brown extensively under heated conditions, unlike inulin.” Oligofructose is about 30% to 60% as sweet as sugar, and contributes 1.5Kcal/g to food formulations, offers Francis.
Studies show inulin can decrease both triglycerides and cholesterol in individuals with high levels of these two lipids, says O'Neill. Additionally, inulin in its many forms can be added to improve digestive health, bone health and overall well-being.
“Inulin can also uniquely function [with some of the properties of] sugar and, therefore, replace a portion of the sugar in products with fiber,” states O'Neill. Consumption can help regulate blood glucose by replacing sugar in foods so the consumer actually eats less sugar. “Inulin works best in dairy products (milk-based drinks, yogurts and ice creams), baked products such as cereals or breads and sweet goods,” he says. It is used as a texturizer, sweetener (sugar replacer) and fat replacer in these systems.
“Inulin is an attractive fat mimetic and bulking agent,” says Francis. “Inulin is prized for its ability to hold water, as well as its bland flavor profile.”
One of the major challenges to whole-grain baking is the dilution of gluten-forming proteins and the cutting action of bran on gluten during mixing, which leads to a decrease in dough stability. Gluten breakdown impacts gas retention and overall volume. “While some choose to increase the amount of gluten to overcome this challenge, others have found that it can be better to replace a portion of flour with inulin instead, and thereby reduce off-flavors that can occur when excess protein is used,” suggests O'Neill.
Inulin has been shown to improve the quality of whole wheat and white bread when used at levels of 2% to 6% of flour weight. “Compared to other fibers, inulin is very easy to formulate with. It is not drying or gritty. I have not seen many formulation issues when manufacturers use it,” opines O'Neill.
Fiber de FactoThe forms of fiber are wide reaching; many gums, sweeteners, starches and other fat replacers also are digested as fiber and may have prebiotic qualities.
While some counter that the dietary fiber guidelines are unrealistic, others believe ingredients like resistant starches, which are more or less produced from cooked and cooled starches, allow consumers to ingest more fiber than they would normally by eating like they always have.
Resistant starches have many of the characteristics of both soluble and insoluble fibers and are commonly used for flour replacement. Unlike whole-grain ingredients, resistant starches have much less impact on taste or texture in many baked goods.
Such ingredients promote regularity and laxation, but because of the slow fermentation characteristics of resistant starch's insoluble structure, it can be consumed at significantly higher quantities, without the digestive side effects common to soluble fibers. In addition, its prebiotic properties help to increase production of short-chain fatty acids (SCFA) in the colon. Particularly important for colon health is butyrate, a SCFA with anti-carcinogenic and anti-inflammatory benefits.
According to Florian Ward, PhD, vice president of research and development for a gum manufacturer, gums always have been an excellent source of soluble dietary fiber. Hydrocolloids such as xanthan and guar gums, carrageenan, alginates and konjac glucomannan can be applied to enrich fiber in bakery, flour products, confectionery, dairy and soft drinks.
Compared to the 12% to 15% soluble fiber found in oat fiber, water-soluble gums contain at least 80% soluble fiber and do not drastically alter the finished viscosity or flavor of a product, explains Ward in a company press statement. “Gums are also multifunctional, in that they supply dietary fiber as well as work to reduce LDL or 'bad' cholesterol levels, inhibit atherosclerosis, speed oral rehydration and improve insulin response,” says Ward. Gums are useful in many forms, from energy bars to drinkable yogurts and emulsified salad dressings.
The most efficacious prebiotics selectively stimulate the production of the SCFA butyrate. Many low-calorie sweeteners and sugar alcohols have prebiotic properties. For example, both tagatose, a low-calorie and low-glycemic sweetener, and polydextrose, a reduced-calorie bulking agent and sugar/fat substitute, are used to encourage the growth of beneficial bacteria.
The list of ingredients that can function as fiber seems almost endless, and two items not previously mentioned include digestion-resistant maltodextrin (DRM) and amorphous cellulose. DRM, a clear, colorless, flavorless and odorless water-soluble fiber that is 90%+ indigestible in humans, often is used as a fat replacer. Amorphous cellulose, from highly refined corn bran, not only acts as a fat replacer, but also provides 80% soluble gellable cellulose fiber and 20% arabinoxylan—the soluble portion of dietary fiber naturally found in the bran and hulls of cereal grains and legumes.
Weaving together the right fibers in the right applications may not be a matter of conscience, but it can give consumers peace of mind about their fiber choices.
Website Resources:www.cfsan.fda.gov/~dms/flgragui.html — Guidance on the recently updated whole-grains label statement
www.conagramills.com— More info on barley ingredients
www.orafti.com — Ingredients from chicory root
www.gtcnutrition.com — All about fructo-oligosaccharides
www.ticgums.com — Hydrocolloids as fibers
www.ztrim.com/benefit.html — Info about amorphous cellulose from corn
www.barleyfoods.org/recipes/bavarian_barley.html — National Barley Foods Council website