Fiber: Fitting Fiber
February 01, 2009
by Rebeca López-García, Ph.D.
Fiber is no longer considered trendy. It is a well established ingredient that will continue to gain popularity. The 2008 International Food Information Council (IFIC) Food and Health Survey on Consumer Attitudes toward Food, Nutrition and Health showed that more than 80% of all Americans say they are currently consuming foods and/or beverages for healthrelated benefits. However, although the health benefits of fiber have been long recognized, Americans are still not consuming nearly enough.
The average fiber intake in the US is approximately 15 g per day. The dietary reference intake (DRI) recommends the consumption of 14 g for every 1000 Cal consumed for everyone over the age of 1. This translates to 25 g for adult women and 38 g for adult men. So, there is still a lot of room for improvement.
Why is it so important to consume all that roughage? In the October 2008 issue of the Journal of the American Dietetic Association (108(10): 1716-1731), ADA stated that populations that consume more dietary fiber have less chronic disease as well as a reduced risk for developing several chronic diseases.
How should a company begin to approach a formulation with additional fiber? One important consideration is the type of fiber that will be added to the product.
Scientific evidence confirms that fibers are not the same, according to Rhonda Witwer, senior business development manager, nutrition, National Starch Food Innovation, Bridgewater, NJ. Nowadays, the fiber market is fragmenting into specific fibers delivering known benefits, with evidence required for those benefits. After all, indigestible ingredients could qualify as dietary fiber that delivers no benefit whatsoever. In the future, continued Ms. Witwer, evidence confirming physiological benefits within humans will be required to call an ingredient a dietary fiber. One of the major challenges is to add enough fiber to be able to make a claim while formulating a highly appealing product and keeping the overall formulation healthy.
The Food and Drug Administration (FDA) allows products that are low in fat and contain at least 20% of the daily reference value (DRV) for fiber (about 5 g) per reference amount to promote themselves as “excellent” sources of fiber. “Good” sources must contain at least 10 to 19% of the DRV. This is a lot of fiber in a low-fat product and cannot be done with the usual wheat bran or oat bran without negatively affecting sensory qualities.
Jody Mattsen, Cargill Bakery Technology research scientist, Cargill, Minneapolis, MN, stated that one good approach to make the fiber claim is to use ingredients that are high in fiber but incorporate them in nonstandard ways. For example, these ingredients could be used as part of a filling or inclusion vs. in the dough. An additional solution is to add specific components of wheat bran such as wheat aleurone, an all-natural ingredient from the aleurone layer of the wheat bran, where most of the desirable wheat nutrients are concentrated.
There are several fiber ingredients that can be used for fat replacement in formulations. Donna Brooks, regional director, Danisco USA, Inc., Elmsford, NY, stated that oftentimes baked foods inherently contain small amounts of fiber, but not enough to make a “good source” or “high in fiber” claim. This is where the addition of polydextrose can help add enough incremental fiber to reach these claims. Polydextrose is a complex carbohydrate mainly composed of randomly crosslinked glucose. It resists digestive enzymes and provides a prebiotic function to intestinal microflora. Polydextrose is a 1-Cal per g bulking agent that shows physiological effects, allowing it to be classified as a fiber and can function as a fat replacer. Brock Lundberg, vice-president of technology, Fiberstar, Inc., River Falls, WI, commented on the use of citrus-based fiber products that can be used for cost, fat and calorie reduction. Mr. Lundberg stated that citrus-based products can be used to help overcome the lack of moisture, texture and mouthfeel of whole-grain products because a small amount (1% or less) is a straightforward way to improve the sensory qualities of the finished product.
Incorporating citrus-based fiber is simple because it does not need to be prehydrated or sheared to function even when it binds large amounts of water. Although this type of fiber cannot be used to substantially increase fiber content, it does reduce fat and calories in formulations.
PIÈCE DE RÉSISTANCE.
Resistant starch is perhaps one of the most innovative groups of ingredients. Ms. Witwer stated that the blandly flavored white powder easily replaces flour to invisibly incorporate dietary fiber into baked products and snacks. She recommended the use of whole-grain corn flour that delivers natural resistant starch combined with whole-grain goodness. With 30% dietary fiber (as natural resistant starch), it enables the formulation of higher-fiber, whole-grain baked foods.
Resistant starches can be used to substitute soluble carbohydrates such as corn syrup to add fiber into confections and fillings. According to Ody Maningat, Ph.D., vice-president, applications technology and technical services, MGP Ingredients, Inc, Atchison, KS, bakers have to contend with processing and finished product issues during fiber formulations. Water absorption, mixing time, dough properties and machinability of fiber-enriched products must not deviate significantly from the unenriched product.
Therefore, bakers must choose a fiber ingredient that has water absorption capabilities similar to flour and possesses neutral taste, white color and fine particle size. It must also have a positive impact on the volume of the baked food. This can be done by directly substituting resistant wheat starches in place of flour. In addition to fiber enhancement, resistant wheat starch also works as a fat replacer.
According to information from Matsutani America, Inc., Decatur, IL, chemically processing starch to create indigestible starch esters, ethers and cross-bonded starches produces resistant maltodextrins (RS4 – see “Classification of Fiber Ingredients,” Page 76). These digestion-resistant maltodextrins offer many processing and formulation advantages because the off-white powder has a clean, neutral flavor, is highly soluble and yields a clear, transparent solution. Also, it is fully stable to heat and acid, and unlike some other resistant starches, it never varies in its fiber content regardless of the product or process. This product is a refined fiber, so formulators can use a high level in many applications without impacting desirable sensory properties.
According to information from Tate & Lyle, Decatur, IL, it is important to avoid using additional water because if the dough becomes too wet, you will still have to drive off the moisture to get a crisp product, and driving off the moisture adds cost. Tate & Lyle’s resistant starch from corn is designed to replace flour and can be used in baked products and snacks.
Its corn fiber product replaces sugar in product applications. Also, the product has a very low water-holding capacity, which Tate & Lyle said makes it easy to formulate products when substituting for wheat flour in lowmoisture systems such as crackers and cookies. Another product, soluble corn fiber, can be used to replace traditional sweeteners such as liquid and dry corn sweeteners, sucrose and other sugar alcohols. As a result, the ingredient can help cut calories by almost half.
DIGESTIVE HEALTH, TOO.
Joseph O’Neill, executive vice-president, sales and marketing, BENEO-Orafti, Inc., Morris Plains, NJ, stated that prebiotic ingredients inulin and oligofructose are ideally suited to the goal of adding a healthy boost of dietary fiber to baked foods.
These products come in different presentations, and ingredient selection depends on the specific application. For example, oligofructose is available as a powder and in liquid form and has excellent humectancy and binding properties. It can be used as a source of “invisible” fiber supplementation imparting virtually no taste to the final product. It can also be useful as a binder and shelf-life extender in cereal bars. Additional functional benefits include partial sugar replacement while contributing a sweetness level 30 to 50% that of sucrose while also contributing to browning reactions in bread and baked foods.
Native inulin can be used as a fiber source in sweet goods and cookies with the added benefit of partially replacing fat and sugar. Mr. O’Neill stated that a newly launched inulin-based ingredient is the best for highfiber baked foods applications because it provides an extra fiber boost to high-fiber and whole-grain bread applications without the need for additional water to hydrate. It does not cause lumping, allows easy dough processing and resists breakdown by yeast enzymes.
Inulin has binding properties in granola formulations, and used in combination with sugar syrups, it binds the particles together resulting in crunchy clusters. It is recommended that the inulin be slowly added to heated syrup before adding any other dry ingredients to allow maximum functionality. In extruded cereal products such as rice crisps where an increase in expansion is required, the maximum concentration of inulin recommended is 30% because higher levels will result in a reduced expansion index.
Oligofructose may be used as a coating or a glaze on baked foods. In cold-formed or baked cereal bars, inulin or oligofructose fiber can be added to the mixture or added as an inclusion. In addition to acting as a source of invisible fiber, inulin may also replace sugar or fat. Fiber delivery systems include chocolate coatings, compound coatings, variegates, inclusions, low-water-activity fruit fillings, variegate layers (for example, caramel) and fruit preparations, concluded Mr. O’Neill.
GUMS AND OTHER INGREDIENTS.
In breads, the use of gums can make the structure so dense that they may seem uncooked even after baking. So gums cannot be used in baking in ranges over approximately 0.6%. Therefore, a gum with 30 to 90% total dietary fiber will deliver only 0.54 g of fiber per 100 g of bread. Gums, however, can be used in baking as dough conditioners.
In 2007, TIC Gums, Belcamp, MD, launched a gum blend of soluble and insoluble fiber that claims to allow bread manufacturers to add high levels of fiber (20% flour replacement) to their products without affecting the bread’s texture. At this level, manufacturers can add 6 g of fiber to a 50-g bread serving.
Arabinogalactan, an ingredient extracted from larch trees, contains more than 90% soluble dietary fiber and helps with moisture retention. It can be effective in developing products with lower water activity. Used at 2 to 10%, it helps extend shelf life, and improves texture and dough handling by reducing stickiness. It is considered a prebiotic that ferments slowly, so it prevents gas and bloating.
Other interesting sources of fiber include sugar beet fiber and bamboo fiber. Obviously, the addition of highfiber ingredients such as whole-grain oats and barley also boosts fiber content. Grain Millers, Inc., Eugene, OR, provides a lightened oat fiber that is useful in applications where a lighter color is expected of the finished product. NutraCea, Phoenix, AZ, provides stabilized rice bran that has a high fiber content, a good antioxidant profile and unique nutritional properties inherent in rice bran. Dehydrated fruits are also good ingredients to increase fiber. TreeTop, Inc., Selah, WA, provides a low-moisture apple fiber that can be used in several bakery applications.
There are many sources of fiber used in baked foods, cereal and snack production. Fiber ingredient selection depends on desired fiber content, water absorption and retention properties, as well as cost and flavor attributes. It is important to understand how all these parameters affect dough processing and finished product quality. It is clear that fiber is no longer the trend of the moment: It is an essential ingredient.