Roughage Times Ahead: 

Roughage Times Ahead: 
Fiber Fortification Done Right

By Kimberly J. 
Decker Contributing Editor 

Heres a riddle: Name a nutrient whose principalcontribution to human health isnt its beneficial digestion products or itscatalysis of metabolic reactions, but instead comes from the fact that no matterhow much of it we eat (and we dont eat nearly enough), it never actuallyenters the body. Need another clue? So convincing is the evidence in favor of this un-nutrientsvalue that the FDA sanctions several health claims aimed explicitly atincreasing its consumption. If youre still stumped, just think, natureslittle broom.

Yes,its dietary fiber, the same old-time roughage that grandmas have sworn by forages. Positive scientific findings combined with a nascent vogue for wholefoods, public-health advocacy and a population entering its later innings hopingto undo the slump it built up earlier in the game are giving Americans plenty ofreason to eat more fiber.

Hypothetically, motivating a fiber-famished public to open wide shouldntbe a tough sellprojected growth in the fiber industry from revenues of $193.1million in 2004 to an estimated $495.2 million by 2011 suggests a bull marketfor fiber-fortified foods, as reported in the Frost & Sullivan study StrategicAnalysis of the United States Food Fiber Industry. But such a market wontdevelop on its own. As the report also states, The appeal for food fiber asan additive is not related to its ability to increase the flavor offoods.

And how. Notwithstanding consumer confidence toward fiber in theory, fiber infact has rarely gotten more than a chilly reception. Perhaps our stepwiseinclination toward refined tastes and textures has doomed coarse, drab fiber toirrevocable second- class status. Nor do manufacturers appreciate the havoc itcan play in formulas where it is not welcome. But the road to roughage neednt be a rough voyage. Knowing whichingredients to use and where to use them can make for smooth sailing.

More than good-for-the-gut 

Technically speaking, because fiber neverbreaches the digestive lining or assimilates itself into our cellular ormetabolic machinery, it never does enter the body. But Ody Maningat, vicepresident, applications technology and technical services, MGP Ingredients,Inc., Atchison, KS, says, Fiber is a nutrient. Its a misconception to say that it just passes through you.

How does an indigestible nutrient benefit health? Chiefly, by improvingconditions in the gastric cavity as it gels and ferments there. For starters,when soluble fibers, such as pectins, gums, mucilages and beta glucansoftencalled viscous fibersform gels in the stomach, they slow, and thus increase, nutrientabsorption in the small intestine. The polysaccharide inulin, for example, isparticularly adept at boosting nutrient uptake, with 15 grams per day evidentlyincreasing the bio-availability of calcium, iron and magnesium.

Some products can improve on that score. According to Kathy Niness, vicepresident, marketing, Orafti Active Food Ingredients, Malvern, PA, a doubleblind placebo-controlled study showed that 8 grams per day of BENEOSynergy 1, a proprietary new enriched form of inulin, increases calciumabsorption 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 wasabsorbed by subjects taking a placebo, whereas those consuming the companys inulin ingredientabsorbed 38%.

Inulin at levels as low as 5 grams per day also encourages the growth ofhealthful lactobacilli and bifidobacteria, crowding out bad microflora inthe process. Thus, it acts as a prebiotic fiberand in this capacity, itsnot alone. A host of other fermentable fibers, both soluble and insoluble, serveas fodder for gut bacteria. When considering a prebiotic fiber, notes JulianaZeiher, ingredient technologies manager, GTC Nutrition, Golden, CO, Theglucose terminals and short chain length are extremely important to thefermentation profile and ingredient functionality, as they determine how easily probiotic bacteria can metabolize it.

As a prebiotic, the 95% active content of scFOS (short-chainfructooligiosaccharides) supports the growth of a wide variety of bifidobacteriaand 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 fattyacids, such as butyrate, they lower colonic pH and thus prime the environmenteven more for their robust growth. Some studies also associate butyrate withcolon-cancer prevention, which, coupled with soluble fibers ability both todilute fecal carcinogens and hasten their transit through the gastrointestinaltract, 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 toharvest cholesterol from the blood to synthesize and replace the lost bile. The upshot: reduced circulating cholesterol levels. For several years, theFDA has permitted foods with at least 0.75 grams per serving of soluble fiberfrom oats to bear the claim, Soluble fiber from foods such as oat bran (oroatmeal, rolled oats, or whole oat flour), as part of a diet low in saturatedfat and cholesterol, may reduce the risk of heart disease. More recently, the FDA gave the goahead to a similar health claim forproducts containing at least 0.75 grams per serving of whole-grain barley ordry-milled barley, after the National Barley Foods Council, Spokane, WA, filed apetition with research showing daily consumption of 3 grams of barley beta-glucans lowered cholesterol by about 5%.

For product designers, that means adding fiber can produce some attention-grabbing headlinesor at least labels. A variety of meaningful healthclaims can be made on fiber-rich foods including nutrient content, health andstructure/function claims, says Zeiher. Most prebiotic- fiber claims onlypertain to products containing soluble fiber, whereas nutrient content claimscan be achieved with both soluble and insoluble fibers.

By forming viscous gels, soluble fibers delay carbohydrate digestion andabsorption, 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 potentiallydisplace 4 or 9 calories from an equal amount of carbohydrate or fat, Foodscontaining fiber are typically healthier and also lower in calories, says JitAng, executive vice president of research and development and businessdevelopment, International Fiber Corporation, North Tonawanda, NY. Therefore,consuming these foods would fit into most dietary plans, from weight-loss dietsto weight-maintenance diets.

And, of course, we dont call it natures 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 toAng. Thats far short of the 25- gram daily reference value (DRV) that theNational Academy of Sciences set for a 2,000-calorie diet, as well as the 2005USDA Dietary Guidelines for Americans recommendation of 14 grams per 1,000calories.

Such targets are worthy goals, for sure, but theyre ambitious for apopulation that, as Ang says, prefers ease rather than health. Evenconscientious eaters, mindful of what fiber does and where it lurks, would havetrouble packing that much into three squares. Dorothy Peterson, product linespecialist for starches, Cargill Food & Pharma Specialties, Minneapolis,observes most people are unwilling to completely change their diet to meet therecommendation and, instead, suggests looking to more nontraditional foods toincorporate fiber so that people actually get close to that recommended amount.

Ang agrees. At this time, most consumers tend to relate fiber withgrain-based foods, such as unrefined grains and the baked goods and breadsmade from their fiber-rich flour and bran. But, he asks, why stop there? Ibelieve that if food technologists can develop good-tasting fiber-fortifiedfoods, we can change the current consumer stereotype of high-fiber foods. Forexample, what is wrong with a fiber-fortified breakfast patty if it tastes good?

Know your limits 

Ah, but thats the question. Consumers are looking for fiber, says Steve Ham, director of marketing for specialty ingredients atMGP, yettaste is always going to win out. Its a matter of making a healthier product without sacrificing the sensoryproperties. A pivotal question he thinks formulators should ask is, Whatsthe goal of balancing how much fiber to add without taking away from the sensoryproperties of the original product?

Its the existential dilemma of the fiber formulator. And at least thegovernment has provided some goalposts to clear. The FDA allows products thatare low in fat and contain at least 20% of the daily value for fiberabout 5gramsper reference amount to promote themselves as excellent sources offiber; 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 nighimpossible. As Maningat says, If you have a food that has a serving size of,lets say, 15 grams, and you have to meet claims for an excellent source offiber, that means you have to have 5 grams of fiber. So youre looking at morethan a 33% incorporation. You cannot do that with wheat bran or oat bran withoutnegatively affecting taste, texture and color.

Fiber fortification, thus, is typically self-limiting. When a food isfortified with fiber, a number of changes will take place, most of which can bedetrimental to texture, flavor and mouth-feel, Ang says. In most cases,over-addition of fiber will cause dryness in the food product, a chalky orgritty mouth-feel, a very dense texture and lack of flavor. That is why it is often difficult to develop great-tasting, high-fiber foodproducts.

Fiber the old-fashioned way 

Of course, what seems dense and gritty inone product might simply be rustic in another. Whole-grain and artisanbreads, hearty wheat crackers, flaked and shredded cereals, granola bars, andeven sweets like oatmeal cookies and homey quick breads have all historicallyhad success as high-fiber foods, in no small part because they often developedthat way. In these applications, the high-fiber medium is the message.

Because such items have evolved for higher fiber levels, formulators andmanufacturers have adapted to fibers effects on processing. As Sarah Schut,market manager, CreaFill Fibers Corp., Chestertown, MD, says, An insolublefiber loves water. It absorbs tremendous amounts of it, holds it and forms amatrix with it. This also can affect product color and moisture release. Thus, bakers of high-fiber foods have learned to increase moisture levels andmix times to account for insoluble fibers hygroscopicity. They may also lengthen baking cycles or raise temperatures to drive off thatlingering water. And they prehydrate fibers that take longer to soften, and useingredient forms that convey the proper color and mouth-feel almostinstinctually.

It always helps, though, when instinct gets a shot of innovation. Theattention directed at fiber has spawned innovative ingredients that, to alloutward appearances, look and perform like the fiber sources of old. For example, Sustagrain barley, an identity-preserved waxy barley fromConAgra Mills, Omaha, NE, improves upon traditional whole-grain barleys fiber and nutritionalbenefits. The company, in conjunction with Montana State University, conventionallybred the barley to have a total dietary fiber (TDF) of 30%, fully half of whichis cholesterol-lowering beta glucan. Thats roughly triple the TDF and solublefiber of conventional whole oats. And with only 30% starchless than half thatof other cerealsits glycemic index (GI) ranks among the lowest for grains.

Adds Beth Arndt, manager of product development at ConAgra Mills, this iswhole-grain barley were dealing with. Part of the benefit of using wholegrain is that youre not just delivering the isolated fiber, youredelivering 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 oatproduct would, says Bill Bonner, ConAgra Mills director of productdevelopment. The steel-cut kernels show up well in soups or anywhere youregoing to have a high moisture content so that itll be able to cook up. Andwhile the lower starch-to-fiber ratio gives the flakes a firmer texturevis-à-vis oats, with the right thickness, Bonner notes, the two areinterchangeable. Just flake it a bit thinner and its indistinguishable,he says. In fact, a 2-to-1 blend of oat flakes with this barley increases theper-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 glutencontent and higher fiber prevent it from replacing wheat flour 1-to-1, hesuggests aiming for a 15% to 40% addition and homing in on the ideal level fromthere. Flatbreads, tortillas and pizza crusts can substitute at higher levels,because they dont 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 0.6grams of beta glucan per reference amount, Arndt adds, you dont need bushelsto make a health claim. The microfine form of the flour, with a particle size ofless than 200 mesh, goes unnoticed in viscous, opaque beverages, smoothies,yogurt, puddings and other products not normally associated with barley betaglucans.

Breaking from tradition 

As fiber suppliers have taken stock of theprofit potential of high-fiber mainstream foods, theyve responded with a rangeof invisible fibersinnocuous both on the palate and in productionthat in some casesnot only dont muck up processing or quality, but even enhance it.

Take fiber and its performance in extruded breakfast cereals. When workingwith extrusion, says Doris Dougherty, senior food scientist, Tate & LyleAmericas, Decatur, IL, you quickly find that the issue is expansion due tothe inability to cook out your base material. But when were trying to fortifyat high levels of fiber, it becomes more and more difficult to cook out thatbase material.

Chalk it up to water management: Modified fibers exert a tenacious moisture grip. Many times, though, youdont want to add that additional water, says Susan Potter, R&Dscientist at Tate & Lyle. You dont want it to come out too wet becauseyou 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 dont get the right mouth-feel and texture. Tate & Lyle hasdeveloped an ingredient system, that when added at roughly 13% to 18% of anextruded breakfast cereals formula (depending on the form of the ingredient),can provide enough fiber per 30-gram serving for a good or excellentsource claim without dampening either expansion or a cerealscharacteristic light, crispy texture. A blend of insoluble oat fiber, modifiedfood starch, maltodextrin, sucralose, natural flavors, and colors, it facilitatesthat cooking and gives the proper expansion and balanced flavor, Dougherty says.

Another fiber source that helps manufacturers eliminate sugar from theirformulas is inulin and the related shorter-chained FOS. There are distinctionsbetween the ingredients that fall into this category. Zeither notes that fructooligosaccharideshas been used almost universally when describing these prebiotic fibers, butcautions that this label is not entirely accurate, and the generalmisunderstanding has occurred specifically because the differences between thethree prebiotic categories were previously not well understood. She termsscFOS a specific, defined mixture of glucoseterminated fructose chains with amaximum chain length of 5 units and 95% pure active prebiotic, which isderived from sugar cane by a natural fermentation process. On the other hand,she describes oligofructose as a mixed FOS, the enzymatic hydrolysisproduct of inulin. It consists of mixed glucose and fructoseterminatedchains, varying in length from two to seven, she says. Inulin is not afructooligosaccharide, because the majority of its chains exceed 10 units. Thismakes inulin a polysaccharide that has some prebiotic properties.

A signal advantage of these soluble polyfructans, which occur naturally asstorage polymers in plants, is their mildly sweet taste. Inulin has a verypleasant flavor, says Sally Romano, vice president, sales and marketing,Sensus America, Monmouth Junction, NJ. And the shorter the chain length, thesweeter the FOS. This comes in handy in formulas aiming both to maximize fiberand minimize carbs. Weve got a liquid inulin that we call sweet liquidfiber thats 50% as sweet as sucrose and only 1.9 kcal per gram, she continues. So in addition to adding fiber, you can replace sweetenersat the same time.

ScFOS is mildly sweet, according to Zeitherabout 30% as sweet as sucroseandonly 1.5 calories per gram. She describes oligofructose as a pleasantly sweethydrolysis product of native inulin, consisting mostly of linked fructoseunits, with some glucose-terminated chains. Oligofructose is about 30% to 60% as sweet as sugar and contributes 1.5kcal/gram.

Product developers who replace some of that sugar with high-intensitysweeteners might also want to consider adding inulin and shortchain FOS fortheir ability to mask the oft-derided aftertaste that haunts some alternativesweeteners. As a bonus, some prebiotic fibers allow for claims such as enhancescalcium absorption, helps build a stronger immune system, good/excellentsource 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 inclusionrates.

Inulin can also help those formulators tackling low-glycemic products. Replacing sugar with inulin lowers the glycemic index of foods which inturn helps control blood sugar levels, says Niness. Inulin may be used toreplace up to 8 grams of sugar per serving in foods and has the added benefitsof being natural and promoting digestive and bone health.

Romano also notes that inulin, unlike some other fibers, doesnt have amarked affinity for water and moderates the effects of more water-seekingfibers. Sometimes manufacturers will use it with insoluble fibers, like wheatfiber, because a lot of those fibers bind a lot of water.

For those looking for the likeliest application candidates, Zeiher lists anumber of emerging products incorporating prebiotic fibers, including kefir,yogurt and other dairy drinks, sports products, functional waters, nutritionbars, weight loss products, soymilk, green foods, probiotic supplements, mineralsupplements, medical foods and pet foods.

Joining the resistance 

Inulin is hardly the least water-binding fiberout there. For that purpose and others, the family of digestion- resistantstarches has really bloomed in recent years as manufacturers have looked tothese ingredients as the ultimate in stealth fiber addition. As Ham notes, Ifyou look at resistant starches, for example, theres very low water-holdingwith a high TDF. So its easy to formulate without having to deal with higherwater levels.

Unlike traditional starches, resistant starches (RS) evade absorption in thesmall intestine while fermenting in the large. Classified into four categoriesRS1 through RS4they generally behave metabolically like insolublecellulose fibers. RS1 is physically trapped within foods, protecting it fromamylolytic enzymes and landing it within the National Academy of Sciencesdefinition of intrinsic and intact dietary fiber. Also considered as such is RS2, a native granular form of starch resilient toenzyme action, except in its gelatinized state. Peterson notes that while RS2sdont have as high a level of total dietary fiber as some other resistantstarches, They do have benefits in terms of being more of a good carb. Theyhave less impact on glycemic response. The RS3 category undergoes physicalretrogradation to a crystalline form of nongranular starch, and RS4, the newestgroup of RS, comprises starches that are chemically modified to make them bothdigestion-resistant and more concentrated in TDF. For example, Fibersol-2, adigestionresistant maltodextrin from ADM, Decatur, IL, analyzes as fully 90% TDF.

Regardless of its subgroup, a resistant starch as a rule boasts the benefitsof small particle sizemaking it less texturally or visually intrusive lower water-absorption, palercolor and blander flavorconsiderably opening the applications to fiberfortification. Notes Allan Buck, research and development, ADM, By simplyremoving soluble carbohydrates, such as corn syrup, and replacing them withFibersol-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 veryclosely match the absorptive capacity of traditional wheat flour, Maningat says,If you have a flour that has a 60% water absorption, a formulator wonteven have to change that when he incorporates resistant starch as a source offiber. Changing to resistant starch also does not impact baking time.

Nevertheless, some applications that could benefit from resistant starchescould also benefit from greater moisture retention. MGP is developing a 70%-TDFresistant starch that, through starch choice and processing modifications, holdsmore moisture than the average resistant starch. Lets say that a typicalwheat-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 waterper gram of starch. And with the fibers shortening-like texture in mind, Ham says, We aregoing to be pursuing dairy applications, sauces, salad dressings. With the addedwater, 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 inthe role of fat mimetic. But these viscous, soluble fibers, under the rightconditions, can also help boost fiber levels in foods. Depending on the benefits you want from the gum, fortification will beeasy or hard, says Mar Nieto, technical services manager, TIC Gums, Inc.,Belcamp, MD. This has to do with gums inherent viscosity and its effects onboth nutrition and product quality. Remember that its through viscosity thata gum interferes with glucose and bile-acid absorption, so to reap a gumsglucose-maintenance and cholesterol-lowering benefits, You want to use thethicker gums that will add viscosity, such as guar gum, konjac, pectin, andlocust bean gum, he says. However, There will be a restriction here becauseyou cannot make a product so thick that nobody will eat it.

The texture of highly hydrated products, such as bread doughs and beverages,suffers when fortified with gums sufficient to achieve their cardio andblood-glucose benefits. In breads, for example, gums will make the structureso dense that, even after baking, parts of it will be so dense that it lookslike its not cooked, Nieto says. Weve done a lot of work using thickgums in bread, and the highest you can use is 1%, bakers percentage. Withwater and other ingredients, it would be lowersay, 0.6%. At a 0.6%addition, even a gum with 80% to 90% TDFaverage for mostwill only deliverabout 0.54 grams of fiber per 100 grams of bread. Figure a single slice weighshalf that and youre not gaining much fiber to crow about. And while suppliers have suggested low-viscosity guar as a solution, byvirtue of its low viscosity, You will still have to use a lot more of the gumfor it to be beneficial to health, he says.

On the other hand, if prebiotic advantages are your goal, the main criterionfor a prebiotic gum is not its viscosity, but rather its suitability tofermentation in the large intestine. The fermentation productsthe short-chain fatty acidsare whatsbeneficial, Nieto says. Sound fermentation candidates include gum arabic, guar gum, pectin, inulinand 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 gums benefits, however, isto take a tag-team approach that blends thick ones with thin. This allows forsignificant fiber levels in beverages, yogurt and other foods otherwise unableto access gums cholesterol and glucose-maintenance benefits. So if I wantto fortify a product mainly to gain prebiotic value, Nieto says, I can useas much gum as I wantas high as 5 grams per servingand it will not have anegative effect on sensory attributes. But if I want to get theglucose-absorption benefit, I would use a thick gum in combination with a thingum to achieve the fortification levels I want. While fiber quantities willof necessity depend on the gum, the product and the serving size, he citeslevels as high as 3.5 grams per serving as realistic.

A few grams here, a few more therepretty soon, meeting those fiberguidelines wont seem that tall an order after all. Thanks to the wideningrange of ingredients available, to say nothing of the products they allow usdevelop, natures little broom looks poised to make a clean sweep of thefortification market.

Kimberly J. Decker, a California-based technical writer, has a B.S. inConsumer 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 andwriting about food. You can reach her at [email protected]. 

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."