Roughage Times Ahead:
Fiber Fortification Done Right
By Kimberly J.
Decker Contributing Editor
Here’s a riddle: Name a nutrient whose principal contribution to human health isn’t its beneficial digestion products or its catalysis of metabolic reactions, but instead comes from the fact that no matter how much of it we eat (and we don’t eat nearly enough), it never actually enters the body. Need another clue? So convincing is the evidence in favor of this un-nutrient’s value that the FDA sanctions several health claims aimed explicitly at increasing its consumption. If you’re still stumped, just think, “nature’s little broom.”
Yes, it’s dietary fiber, the same old-time roughage that grandmas have sworn by for ages. Positive scientific findings combined with a nascent vogue for whole foods, public-health advocacy and a population entering its later innings hoping to undo the slump it built up earlier in the game are giving Americans plenty of reason to eat more fiber.
Hypothetically, motivating a fiber-famished public to open wide shouldn’t be a tough sell—projected growth in the fiber industry from revenues of $193.1 million in 2004 to an estimated $495.2 million by 2011 suggests a bull market for fiber-fortified foods, as reported in the Frost & Sullivan study Strategic Analysis of the United States Food Fiber Industry. But such a market won’t develop on its own. As the report also states, “The appeal for food fiber as an additive is not related to its ability to increase the flavor of foods.”
And how. Notwithstanding consumer confidence toward fiber in theory, fiber in fact has rarely gotten more than a chilly reception. Perhaps our stepwise inclination toward refined tastes and textures has doomed coarse, drab fiber to irrevocable second- class status. Nor do manufacturers appreciate the havoc it can play in formulas where it is not welcome. But the road to roughage needn’t be a rough voyage. Knowing which ingredients to use and where to use them can make for smooth sailing.
 Photo: ADM |
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Resistant starches help boost the fiber content of baked goods while contributing little flavor to the food. |
More than good-for-the-gut
Technically speaking, because fiber never breaches the digestive lining or assimilates itself into our cellular or metabolic machinery, it never does enter the body. But Ody Maningat, vice president, applications technology and technical services, MGP Ingredients, Inc., Atchison, KS, says, “Fiber is a nutrient. It’s a misconception to say that it just passes through you.”
How does an indigestible nutrient benefit health? Chiefly, by improving conditions in the gastric cavity as it gels and ferments there. For starters, when soluble fibers, such as pectins, gums, mucilages and beta glucans—often called “viscous” fibers—form gels in the stomach, they slow, and thus increase, nutrient absorption in the small intestine. The polysaccharide inulin, for example, is particularly adept at boosting nutrient uptake, with 15 grams per day evidently increasing the bio-availability of calcium, iron and magnesium.
Some products can improve on that score. According to Kathy Niness, vice president, marketing, Orafti Active Food Ingredients, Malvern, PA, a double blind placebo-controlled study showed that “8 grams per day of BENEO™ Synergy 1, a proprietary new enriched form of inulin, increases calcium absorption by 20%.” In this study, published in the British Journal of Nutrition, 87 (Supplement 2), May 2002, page S187-S19, 32% of the consumed calcium was absorbed by subjects taking a placebo, whereas those consuming the company’s inulin ingredient absorbed 38%.
Inulin at levels as low as 5 grams per day also encourages the growth of healthful lactobacilli and bifidobacteria, crowding out “bad” microflora in the process. Thus, it acts as a prebiotic fiber—and in this capacity, it’s not alone. A host of other fermentable fibers, both soluble and insoluble, serve as fodder for gut bacteria. When considering a prebiotic fiber, notes Juliana Zeiher, ingredient technologies manager, GTC Nutrition, Golden, CO, “The glucose terminals and short chain length are extremely important to the fermentation profile and ingredient functionality,” as they determine how easily probiotic bacteria can metabolize it.
“As a prebiotic, the 95% active content of scFOS (short-chain fructooligiosaccharides) supports the growth of a wide variety of bifidobacteria and lactobacilli strains, and does not support the growth of pathogens in vivo,” she points out.
As lactobacilli and bifidobacteria ferment these fibers to short-chain fatty acids, such as butyrate, they lower colonic pH and thus prime the environment even more for their robust growth. Some studies also associate butyrate with colon-cancer prevention, which, coupled with soluble fiber’s ability both to dilute fecal carcinogens and hasten their transit through the gastrointestinal tract, argues convincingly for fiber as a cancer fighter.
The case for its role in cardiovascular health is even more persuasive. Soluble, viscous fibers inhibit bileacid absorption, forcing the liver to harvest cholesterol from the blood to synthesize and replace the lost bile. The upshot: reduced circulating cholesterol levels. For several years, the FDA has permitted foods with at least 0.75 grams per serving of soluble fiber from oats to bear the claim, “Soluble fiber from foods such as oat bran (or oatmeal, rolled oats, or whole oat flour), as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.” More recently, the FDA gave the goahead to a similar health claim for products containing at least 0.75 grams per serving of whole-grain barley or dry-milled barley, after the National Barley Foods Council, Spokane, WA, filed a petition with research showing daily consumption of 3 grams of barley beta-glucans lowered cholesterol by about 5%.
 Photo: ADM |
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When swapping flour for resistant starch in a baked snack, product designers usually do not have to alter baking times, partially due to the low water-holding capacity of resistant starches. |
For product designers, that means adding fiber can produce some attention- grabbing headlines—or at least labels. “A variety of meaningful health claims can be made on fiber-rich foods including nutrient content, health and structure/function claims,” says Zeiher. “Most prebiotic- fiber claims only pertain to products containing soluble fiber, whereas nutrient content claims can be achieved with both soluble and insoluble fibers.”
By forming viscous gels, soluble fibers delay carbohydrate digestion and absorption, helping maintain circulating blood glucose levels, dampening fluctuations in glycemic response, and increasing insulin sensitivity, while also extending feelings of satiety. Given that every gram of an effectively noncaloric fiber can potentially displace 4 or 9 calories from an equal amount of carbohydrate or fat, “Foods containing fiber are typically healthier and also lower in calories,” says Jit Ang, executive vice president of research and development and business development, International Fiber Corporation, North Tonawanda, NY. “Therefore, consuming these foods would fit into most dietary plans, from weight-loss diets to weight-maintenance diets.”
And, of course, we don’t call it “nature’s little broom” for nothing: Fiber, particularly insoluble, is the laxation aid for the ages.
How much is enough?
Pity, then, that Americans average only 10 to 15 grams per day, according to Ang. That’s far short of the 25- gram daily reference value (DRV) that the National Academy of Sciences set for a 2,000-calorie diet, as well as the 2005 USDA Dietary Guidelines for Americans recommendation of 14 grams per 1,000 calories.
Such targets are worthy goals, for sure, but they’re ambitious for a population that, as Ang says, “prefers ease rather than health.” Even conscientious eaters, mindful of what fiber does and where it lurks, would have trouble packing that much into three squares. Dorothy Peterson, product line specialist for starches, Cargill Food & Pharma Specialties, Minneapolis, observes most people are unwilling to completely change their diet to meet the recommendation and, instead, suggests “looking to more nontraditional foods to incorporate fiber so that people actually get close to that recommended amount.”
Ang agrees. “At this time, most consumers tend to relate fiber with grain-based foods,” such as unrefined grains and the baked goods and breads made from their fiber-rich flour and bran. But, he asks, why stop there? “I believe that if food technologists can develop good-tasting fiber-fortified foods, we can change the current consumer stereotype of high-fiber foods. For example, what is wrong with a fiber-fortified breakfast patty if it tastes good?”
Know your limits
Ah, but that’s the question. “Consumers are looking for fiber,” says Steve Ham, director of marketing for specialty ingredients at MGP, “yet taste is always going to win out. It’s a matter of making a healthier product without sacrificing the sensory properties.” A pivotal question he thinks formulators should ask is, “What’s the goal of balancing how much fiber to add without taking away from the sensory properties of the original product?”
 Photo: ADM |
| Fortifying a bar application with resistant maltodextrin not only boosts soluble-fiber levels, it can help extend the bar’s shelf life. |
It’s the existential dilemma of the fiber formulator. And at least the government has provided some goalposts to clear. The FDA allows products that are low in fat and contain at least 20% of the daily value for fiber—about 5 grams—per reference amount to promote themselves as “excellent” sources of fiber; “good” sources must contain at least 10%, or 2.5 grams, per serving.
But squeezing even that much fiber into some serving sizes can be well nigh impossible. As Maningat says, “If you have a food that has a serving size of, let’s say, 15 grams, and you have to meet claims for an excellent source of fiber, that means you have to have 5 grams of fiber. So you’re looking at more than a 33% incorporation. You cannot do that with wheat bran or oat bran without negatively affecting taste, texture and color.”
Fiber fortification, thus, is typically self-limiting. “When a food is fortified with fiber, a number of changes will take place, most of which can be detrimental to texture, flavor and mouth-feel,” Ang says. “In most cases, over-addition of fiber will cause dryness in the food product, a chalky or gritty mouth-feel, a very dense texture and lack of flavor. That is why it is often difficult to develop great-tasting, high-fiber food products.”
Fiber the old-fashioned way
Of course, what seems dense and gritty in one product might simply be “rustic” in another. Whole-grain and artisan breads, hearty wheat crackers, flaked and shredded cereals, granola bars, and even sweets like oatmeal cookies and homey quick breads have all historically had success as high-fiber foods, in no small part because they often developed that way. In these applications, the high-fiber medium is the message.
Because such items have evolved for higher fiber levels, formulators and manufacturers have adapted to fiber’s effects on processing. As Sarah Schut, market manager, CreaFill Fibers Corp., Chestertown, MD, says, “An insoluble fiber loves water. It absorbs tremendous amounts of it, holds it and forms a matrix with it.” This also can affect product color and moisture release. Thus, bakers of high-fiber foods have learned to increase moisture levels and mix times to account for insoluble fiber’s hygroscopicity. They may also lengthen baking cycles or raise temperatures to drive off that lingering water. And they prehydrate fibers that take longer to soften, and use ingredient forms that convey the proper color and mouth-feel almost instinctually.
It always helps, though, when instinct gets a shot of innovation. The attention directed at fiber has spawned innovative ingredients that, to all outward appearances, look and perform like the fiber sources of old. For example, Sustagrain barley, an identity-preserved waxy barley from ConAgra Mills, Omaha, NE, improves upon traditional whole-grain barley’s fiber and nutritional benefits. The company, in conjunction with Montana State University, conventionally bred the barley to have a total dietary fiber (TDF) of 30%, fully half of which is cholesterol-lowering beta glucan. That’s roughly triple the TDF and soluble fiber of conventional whole oats. And with only 30% starch—less than half that of other cereals—its glycemic index (GI) ranks among the lowest for grains.
 Photo: Orafti Active Food Ingredients |
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Adding inulin to yogurt products contributes prebiotic fiber while providing other health benefits, including increased calcium absorption by the consumer. |
Adds Beth Arndt, manager of product development at ConAgra Mills, this is whole-grain barley we’re dealing with. “Part of the benefit of using whole grain is that you’re not just delivering the isolated fiber, you’re delivering the entire nutrient package, including lipids, proteins, vitamins, minerals, flavonoids and other phytonutrients,” she says.
Flaked and steel-cut forms of the ingredient work wherever an analogous oat product would, says Bill Bonner, ConAgra Mills’ director of product development. The steel-cut kernels show up well in soups or “anywhere you’re going to have a high moisture content so that it’ll be able to cook up.” And while the lower starch-to-fiber ratio gives the flakes a firmer texture vis-à-vis oats, “with the right thickness,” Bonner notes, the two are interchangeable. “Just flake it a bit thinner and it’s indistinguishable,” he says. In fact, a 2-to-1 blend of oat flakes with this barley increases the per-serving fiber in a hot cereal by 50% without affecting taste or texture.
In flour form, the barley can strengthen fiber levels in baked goods, extruded cereals, snacks and pasta, Bonner continues. While its minimal gluten content and higher fiber prevent it from replacing wheat flour 1-to-1, he suggests aiming for a 15% to 40% addition and homing in on the ideal level from there. Flatbreads, tortillas and pizza crusts can substitute at higher levels, because they don’t need the lift or gluten structure of highly risen bread. And the company has developed a pasta that substitutes the barley flour for 30% of the durum semolina. With only 4 grams of the ingredient needed to deliver 0.6 grams of beta glucan per reference amount, Arndt adds, you don’t need bushels to make a health claim. The microfine form of the flour, with a particle size of less than 200 mesh, goes unnoticed in viscous, opaque beverages, smoothies, yogurt, puddings and other products not normally associated with barley beta glucans.
Breaking from tradition
As fiber suppliers have taken stock of the profit potential of high-fiber mainstream foods, they’ve responded with a range of “invisible” fibers—innocuous both on the palate and in production—that in some cases not only don’t muck up processing or quality, but even enhance it.
Take fiber and its performance in extruded breakfast cereals. “When working with extrusion,” says Doris Dougherty, senior food scientist, Tate & Lyle Americas, Decatur, IL, “you quickly find that the issue is expansion due to the inability to cook out your base material. But when we’re trying to fortify at high levels of fiber, it becomes more and more difficult to cook out that base material.”
Chalk it up to water management: Modified fibers exert a tenacious moisture grip. Many times, though, “you don’t want to add that additional water,” says Susan Potter, R&D scientist at Tate & Lyle. “You don’t want it to come out too wet because you still have to drive that moisture off to get a crisp product. Driving off moisture adds cost, and if you fail to drive off that moisture, you don’t get the right mouth-feel and texture.” Tate & Lyle has developed an ingredient system, that when added at roughly 13% to 18% of an extruded breakfast cereal’s formula (depending on the form of the ingredient), can provide enough fiber per 30-gram serving for a “good” or “excellent” source claim without dampening either expansion or a cereal’s characteristic light, crispy texture. A blend of insoluble oat fiber, modified food starch, maltodextrin, sucralose, natural flavors, and colors, it “facilitates that cooking and gives the proper expansion and balanced flavor,” Dougherty says.
Another fiber source that helps manufacturers eliminate sugar from their formulas is inulin and the related shorter-chained FOS. There are distinctions between the ingredients that fall into this category. Zeither notes that “fructooligosaccharides” has been used almost universally when describing these prebiotic fibers, but cautions that “this label is not entirely accurate, and the general misunderstanding has occurred specifically because the differences between the three prebiotic categories were previously not well understood.” She terms scFOS “a specific, defined mixture of glucoseterminated fructose chains with a maximum chain length of 5 units and 95% pure active prebiotic,” which is derived from sugar cane by a natural fermentation process. On the other hand, she describes oligofructose as a “mixed FOS,” the enzymatic hydrolysis product of inulin. “It consists of mixed glucose and fructoseterminated chains, varying in length from two to seven, she says. “Inulin is not a fructooligosaccharide, because the majority of its chains exceed 10 units. This makes inulin a polysaccharide that has some prebiotic properties.”
A signal advantage of these soluble polyfructans, which occur naturally as storage polymers in plants, is their mildly sweet taste. “Inulin has a very pleasant flavor,” says Sally Romano, vice president, sales and marketing, Sensus America, Monmouth Junction, NJ. And the shorter the chain length, the sweeter the FOS. This comes in handy in formulas aiming both to maximize fiber and minimize carbs. “We’ve got a liquid inulin that we call ‘sweet liquid fiber’™ that’s 50% as sweet as sucrose and only 1.9 kcal per gram,” she continues. “So in addition to adding fiber, you can replace sweeteners at the same time.”
ScFOS is mildly sweet, according to Zeither—about 30% as sweet as sucrose—and only 1.5 calories per gram. She describes oligofructose as “a pleasantly sweet hydrolysis product of native inulin,” consisting mostly of linked fructose units, with some glucose-terminated chains. Oligofructose is about 30% to 60% as sweet as sugar and contributes 1.5 kcal/gram.
Product developers who replace some of that sugar with high-intensity sweeteners might also want to consider adding inulin and shortchain FOS for their ability to mask the oft-derided aftertaste that haunts some alternative sweeteners. As a bonus, “some prebiotic fibers allow for claims such as ‘enhances calcium absorption,’ ‘helps build a stronger immune system,’ ‘good/excellent source of fiber,’ ‘for optimal digestive health’ and more,” says Zeiher. “The opportunity to make claims will vary depending on the fiber source, the application used and inclusion rates.”
Inulin can also help those formulators tackling low-glycemic products. “Replacing sugar with inulin lowers the glycemic index of foods which in turn helps control blood sugar levels,” says Niness. “Inulin may be used to replace up to 8 grams of sugar per serving in foods and has the added benefits of being natural and promoting digestive and bone health.”
Romano also notes that inulin, unlike some other fibers, doesn’t have a marked affinity for water and moderates the effects of more water-seeking fibers. “Sometimes manufacturers will use it with insoluble fibers, like wheat fiber, because a lot of those fibers bind a lot of water.”
For those looking for the likeliest application candidates, Zeiher lists a number of emerging products incorporating prebiotic fibers, including kefir, yogurt and other dairy drinks, sports products, functional waters, nutrition bars, weight loss products, soymilk, green foods, probiotic supplements, mineral supplements, medical foods and pet foods.
Joining the resistance
Inulin is hardly the least water-binding fiber out there. For that purpose and others, the family of digestion- resistant starches has really bloomed in recent years as manufacturers have looked to these ingredients as the ultimate in stealth fiber addition. As Ham notes, “If you look at resistant starches, for example, there’s very low water-holding with a high TDF. So it’s easy to formulate without having to deal with higher water levels.”
 Photo: ADM |
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Beta-glucan-rich barley flour can replace a high level of wheat or white flour in flatbreads and other unleavened baked goods. |
Unlike traditional starches, resistant starches (RS) evade absorption in the small intestine while fermenting in the large. Classified into four categories —RS1 through RS4—they generally behave metabolically like insoluble cellulose fibers. RS1 is physically trapped within foods, protecting it from amylolytic enzymes and landing it within the National Academy of Sciences’ definition of intrinsic and intact “dietary fiber.” Also considered as such is RS2, a native granular form of starch resilient to enzyme action, except in its gelatinized state. Peterson notes that while RS2s don’t have as high a level of total dietary fiber as some other resistant starches, “They do have benefits in terms of being more of a good carb. They have less impact on glycemic response.” The RS3 category undergoes physical retrogradation to a crystalline form of nongranular starch, and RS4, the newest group of RS, comprises starches that are chemically modified to make them both digestion-resistant and more concentrated in TDF. For example, Fibersol-2, a digestionresistant maltodextrin from ADM, Decatur, IL, analyzes as fully 90% TDF.
Regardless of its subgroup, a resistant starch as a rule boasts the benefits of small particle size—making it less texturally or visually intrusive —lower water-absorption, paler color and blander flavor—considerably opening the applications to fiber fortification. Notes Allan Buck, research and development, ADM, “By simply removing soluble carbohydrates, such as corn syrup, and replacing them with Fibersol-2, at 90%-plus fiber, we can put fiber into confections, beverages, frozen desserts, sauces, fillings, condiments, and so on.”
Because some resistant starches’ low water-holding capacity can very closely match the absorptive capacity of traditional wheat flour, Maningat says, “If you have a flour that has a 60% water absorption, a formulator won’t even have to change that when he incorporates resistant starch as a source of fiber.” Changing to resistant starch also does not impact baking time.
Nevertheless, some applications that could benefit from resistant starches could also benefit from greater moisture retention. MGP is developing a 70%-TDF resistant starch that, through starch choice and processing modifications, holds more moisture than the average resistant starch. “Let’s say that a typical wheat-based resistant starch will absorb 0.7 grams of water per gram of starch,” Maningat says. “We can change our process to raise that to 2 grams of water per gram of starch.” And with the fiber’s shortening-like texture in mind, Ham says, “We are going to be pursuing dairy applications, sauces, salad dressings. With the added water, we see the possibility to replace fat in addition to adding fiber.”
By gum!
Most fat-reduced sauces and salad dressings cast gums and hydrocolloids in the role of fat mimetic. But these viscous, soluble fibers, under the right conditions, can also help boost fiber levels in foods. “Depending on the benefits you want from the gum, fortification will be easy or hard,” says Mar Nieto, technical services manager, TIC Gums, Inc., Belcamp, MD. This has to do with gum’s inherent viscosity and its effects on both nutrition and product quality. Remember that it’s through viscosity that a gum interferes with glucose and bile-acid absorption, so to reap a gum’s glucose-maintenance and cholesterol-lowering benefits, “You want to use the thicker gums that will add viscosity,” such as guar gum, konjac, pectin, and locust bean gum, he says. However, “There will be a restriction here because you cannot make a product so thick that nobody will eat it.”
 Photo: Orafti Active Food Ingredients |
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Inulin can add "hidden" processing advantages to some bar applications. For example, inulin can help cereal bars maintain their shape, which aids extrusion and packaging. |
The texture of highly hydrated products, such as bread doughs and beverages, suffers when fortified with gums sufficient to achieve their cardio and blood-glucose benefits. In breads, for example, gums “will make the structure so dense that, even after baking, parts of it will be so dense that it looks like it’s not cooked,” Nieto says. “We’ve done a lot of work using thick gums in bread, and the highest you can use is 1%, baker’s percentage. With water and other ingredients, it would be lower—say, 0.6%.” At a 0.6% addition, even a gum with 80% to 90% TDF—average for most—will only deliver about 0.54 grams of fiber per 100 grams of bread. Figure a single slice weighs half that and you’re not gaining much fiber to crow about. And while suppliers have suggested low-viscosity guar as a solution, by virtue of its low viscosity, “You will still have to use a lot more of the gum for it to be beneficial to health,” he says.
On the other hand, if prebiotic advantages are your goal, the main criterion for a prebiotic gum is not its viscosity, but rather its suitability to fermentation in the large intestine. “The fermentation products—the short-chain fatty acids—are what’s beneficial,” Nieto says. Sound fermentation candidates include gum arabic, guar gum, pectin, inulin and gum acacia, but the latter two stand out for their marked lack of viscosity, meaning that “you can load your food with a lot of them,” he says.
The most effective way to load a product with gum’s benefits, however, is to take a tag-team approach that blends thick ones with thin. This allows for significant fiber levels in beverages, yogurt and other foods otherwise unable to access gum’s cholesterol and glucose-maintenance benefits. “So if I want to fortify a product mainly to gain prebiotic value,” Nieto says, “I can use as much gum as I want—as high as 5 grams per serving—and it will not have a negative effect on sensory attributes. But if I want to get the glucose-absorption benefit, I would use a thick gum in combination with a thin gum to achieve the fortification levels I want.” While fiber quantities will of necessity depend on the gum, the product and the serving size, he cites levels as high as 3.5 grams per serving as realistic.
A few grams here, a few more there—pretty soon, meeting those fiber guidelines won’t seem that tall an order after all. Thanks to the widening range of ingredients available, to say nothing of the products they allow us develop, nature’s little broom looks poised to make a clean sweep of the fortification market.
Kimberly J. Decker, a California-based technical writer, has a B.S. in Consumer Food Science with a minor in English from the University of California, Davis. She lives in the San Francisco Bay area, where she enjoys eating and writing about food. You can reach her at kim@decker.net.
What's in a Name?
Believe it or not, dowdy old fiber has courted some controversy of late as industry, regulatory and research bodies have attempted to craft a common definition for it. In doing so, they've also illustrated how even a noble public health effort can set interests at odds when it seeks to reconcile society's need for healthful foods with consumers' insistence on sensory pleasure.
Through the end of the last century, we defined fiber in terms of chemistry and extraction methodology: Is it susceptible to enzymatic digestion, and does it dissolve in ethanol solution? While this took in both common insoluble fibers such as cellulose, hemicellulose, vegetable brans and lignins, and the water-soluble gums, pectins and beta-glucans, one of its weaknesses was its exclusion of oligo- and polysaccharides, such as inulin, and some resistant starches that, while falling short of the aforementioned criteria, still exhibit fiber's salutary effects.
Early in 2001, the American Association of Cereal Chemists (now AACC International, St. Paul, MN) thus widened its definition to account for health as well as for chemistry. "Dietary fiber," it said, "is the edible parts of plants or analogous carbohydrates that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the large intestine. Dietary fiber includes polysaccharides, oligosaccharides, lignin, and associated plant substances. Dietary fibers promote beneficial physiological effects including laxation, and/or blood-cholesterol attenuation, and/or blood-glucose attenuation."
Meanwhile, the Food and Nutrition Board (FNB) of the Institutes of Medicine at the National Academies, Washington, DC, proposed its own slightly divergent definition. In the FNB scheme, total fiber equals the sum of dietary fiber--the "nondigestible carbohydrates and lignin that are intrinsic and intact in plants"--plus functional fiber, "isolated, nondigestible carbohydrates that have beneficial physiological effects in humans."
The two classifications correspond in acknowledging fiber's indigestibility and physiological benefits. Where they and their respective proponents diverge concerns the ambiguity of "intrinsic and intact." Because the FNB attributes fiber's healthfulness to its native presence as a complex matrix of elements, any one of which many not function in isolation, they believe that their strict-construction definition protects consumers from foods fortified with isolated fibers that, in vivo, don't do much. For their part, AACC International and its industry partners contend that such picayune distinctions only confuse consumers and limit the scope of ingredients available to formulate high-fiber foods that people actually like--and buy.
The good news is that in the absence of a universal standard, manufacturers can continue operating much as they have. As Ody Maningat, vice president, applications technology and technical services, MGP Ingredients, Inc., Atchison, KS, says, the brouhaha "doesn't have any effect on our day-to-day formulations." Adds his colleague, Steve Ham, director of marketing for specialty ingredients, fiber's definition "is somewhat black-and-white in that if you run an analysis and you get a certain dietary fiber content, you can use that on a package." Identify your product's constituent fibers--intrinsic or added--quantify them through independent analysis, and you should be in the clear.
Solving the Insoluble
We know that both soluble and insoluble fiber are good for us. But is each equally good for the product application? Not by a long shot. Says Sarah Schut, market manager, CreaFill Fibers Corp., Chestertown, MD, "It is a constant battle within industry to inform people about the difference between soluble and insoluble fiber, because they do perform very differently."
Although neither is digestible in an aqueous enzyme solution, insoluble fibers--think celluloses, hemicelluloses, lignins and resistant starches--fall right out of solution, while the soluble hydrocolloids, pectins and beta glucans remain in solution until treated to alcohol addition. (Although inulin, fructooligosaccharides, and some resistant maltodextrins don't conform to this extraction duality, we still include them in the soluble-fiber category.) But what does that mean for formulation? It depends on what you're formulating.
"Soluble fibers, especially gums, can sometimes increase the viscosity of food systems. Insoluble fibers, on the other hand, can affect mouthfeel," explains Jit Ang, executive vice president of research and development and business development, International Fiber Corporation, North Tonawanda, NY. "Normally food applications that require a smooth and creamy mouthfeel will lean toward the use of soluble fibers, while, in general, grain-based products are easier to fortify with insoluble fibers."
Take the case of a beverage. Says Allan Buck, research and development, ADM, Decatur, IL, "You would not use an insoluble fiber in a clear, acidic fruit-flavored drink due to clarity problems." Other reasons for its disqualification include that, without help, it will fall out of suspension and settle as grit on the bottom of the bottle. Soluble fibers make much better fortification choices, especially if the beverage benefits from the soluble fiber's viscosity, as might a smoothie. Of course, not all beverages do; as Buck points out, "Soluble fibers such as oat fiber or psyllium create excess viscosity in a beverage at common fortification levels, and others, such as inulin, break down under low pH and high-temperatures processing." His suggestion then is to use a digestion-resistant maltodextrin, which "is unique in that it is capable of delivering high dietary-fiber levels without negatively impacting the appearance, texture or flavor in many finished foods or beverages."
A soluble fiber's viscosity might also impede its utility in baked goods. Says Dorothy Peterson, product line specialist for starches, Cargill Food & Pharma Specialties, Minneapolis: "The soluble fibers have some functional aspects that sometimes make them a little more difficult to incorporate into a grain-based product. They tend to have more ability to bind and hold water, which is usually something that's fairly negative if you're trying to put the fiber into a baked good or cereal or snack." Again, look to insoluble sources when fortifying these applications.
"Noting the differences between soluble and insoluble fiber is going to be critical, as well as knowing the origin of the fiber," Schut concludes. "And I think that with food as a whole, product developers are going to have to look at combining the benefits of these different fibers. That's where I really see soluble and insoluble fibers having to work together. I think they achieve different things in products."
