Fibersym®RW is a food-grade resistant wheat starch belonging to the RS4 classification of resistant starch.
The term “resistant starch” was coined in 1982 when British research scientists discovered the existence of enzyme-resistant starch in bread and cooked and cooled potatoes. The official definition for resistant starch was developed in 1992, which states that it is “the sum of starch and products of starch degradation not absorbed in the small intestines of healthy individuals”.
Resistant starch is part of dietary fiber. The newly adopted Codex definition for dietary fiber as well as the fiber definitions of several organizations and regulatory agencies of many countries includes resistant starch in the definition of dietary fiber. In essence, resistant starch is a dietary fiber.
Not all resistant starches are the same. In fact, they are classified into five types. Type 1 or RS1 occurs in whole grains or incompletely or coarsely-milled cereal grains, seeds, and legumes. Examples are cracked wheat, farina, semolina, red beans, pinto beans, and white beans. The starch granules are encapsulated within a cell wall matrix so that the digestive enzymes are prevented or delayed from having access to them. The gastrointestinal tract of humans lacks enzymes capable of degrading the components of cell walls in order to expose the physically-shielded starch granules. The amount of RS1 is affected by processing and can actually be decreased or eliminated by complete disintegration or fine milling. Commercially, flours and meals from high-amylose corn and flours from high-amylose barley are available for use as resistant starch source in food product development.
Examples of type 2 or RS2 are starch granules from raw potato, unripe or green banana, and high-amylose corn, wheat, barley or rice. Their starch granules are resistant to enzymatic digestion by virtue of their inherent crystalline structure. Like RS1, the amount of RS2 can be affected by processing. Raw potato and raw banana starch lose resistance to enzyme digestion upon cooking. High-amylose corn starch with varying levels of RS2 resistant starch contents are currently sold in the market.
Recrystallized amylose or retrograded amylose represents resistant starch belonging to type 3 or RS3. Retrogradation is a time- and temperature-dependent process after starch has been cooked or gelatinized. The intimate association of amylose results in the formation of water-insoluble semi-crystalline structures thereby preventing the enzyme from digesting them. This type of resistant starch can be generated in processed foods as in cooked and cooled potato, cooked and cooled rice as well as in bread and corn flakes. RS3 products based on tapioca starch, normal corn starch, and high-amylose corn starch are commercially available.
Type 4 or RS4 occurs in chemically modified starch. All forms of chemically modified starch have varying degrees of resistance to enzyme digestion. Some of MGPI’s modified wheat starch products like Midsol™ 1, Midsol™ 46 or Pregel™ 40 offer some resistance to digestion, but the magnitude of resistance is low and they offer no commercial value as a significant source of resistant starch. One form of modification that is accomplished by cross-linking starch with sodium trimetaphosphate in the presence of small amounts of sodium tripolyphosphate, imparts the highest level of resistance to enzyme digestion. Two products made by such process are Fibersym® RW and FiberRite® RW. Due to the high degree of cross-linking, these two starches have limited swelling when heated and the tight structure coupled with steric effect inhibit enzymatic digestion. Through MGPI’s sublicensing agreements, other RS4 commercial products are available such as those from potato and tapioca starch that have been modified using the same technology as Fibersym® RW. Resistant starch products abound in the RS4 category. Dextrins from corn and wheat produced by three manufacturers also compete in this RS4 market.
The fifth type or RS5 was recently introduced as a new type of resistant starch. It occurs as starch-lipid or amylose-lipid complex that forms when starchy foods are heated or cooked in the presence of fats or lipids. This durable complex offers resistance to enzymatic digestion based on steric hindrance by the complex. Currently, there is no commercially-manufactured RS5 resistant starch available in the market.
It has been long recognized that there are two kinds of conventional fiber --- insoluble fiber and soluble fiber. Insoluble fiber is represented by cellulose, lignin and some insoluble hemicelluloses. Soluble fiber is represented by pectins, gums, mucilages, inulin, fructooligosaccharides and some soluble hemicelluloses.
Resistant starch originates from starch in foods that escapes digestion in the small intestine. It differs compositionally from the conventional fibers by being from a starch source.
When hydrated, 1 gram of Fibersym®RW absorbs 0.7 grams of water, which is similar to the absorption capacity of wheat flour. This translates to ease of formulation when Fibersym®RW is used to replace wheat flour in bakery products as water absorption and baking time remain unchanged.
The production process for Fibersym®RW involves treatment of wheat starch with sodium trimetaphosphate (a cross-linking agent) and sodium tripolyphosphate (a substituting agent) yielding a highly cross-linked wheat starch containing small levels of substituents. The level of chemicals during reaction and residues in final product (no more than 0.4% phosphorus) comply with 21 CFR 172.892.
The chemical name for Fibersym®RW is phosphated distarch phosphate. Its Chemical Abstract Service (CAS) Number is 11120-02-8 and E-number is 1413.
Fibersym®RW delivers a minimum total dietary fiber of 85% (dry basis). The method used to determine total dietary fiber is AOAC Method 991.43.
Fibersym® RW is a source of insoluble fiber as do other resistant starches like Hi-Maize, Novelose, and ActiStar. Counterpart products that are considered a source of soluble fiber are inulin, fructooligosaccharides, Nutriose, and Fibersol.
The recommended labeling statement for Fibersym®RW is “modified wheat starch”. It complies with 21 CFR 172.892 and the Food Labeling and Consumer Protection Act of 2006, which requires that the botanical source of starch be declared.
There is no commercially-grown wheat in the U.S. that is genetically modified (GMO). Because the source of raw material wheat for manufacturing of Fibersym®RW is 100% domestic, it is considered non-GMO.
Fibersym®RW has several advantages over other resistant starches as well as conventional dietary fibers. They are enumerated as follows:
Fibersym®RW, when formulated in a nutritional bar, reduces the glycemic and insulin response of healthy individuals as well as type 2 diabetics. The results will assist these individuals to their blood glucose levels, which consequently may have a positive impact on avoiding weight gain. This particular study was conducted at Kansas State University.
Fibersym®RW was also formulated in snack crackers to determine the effect on gut health. Daily consumption of crackers for three weeks showed a significant increase (more than three-fold) of bifidobacteria indicating a prebiotic effect. This study was completed at the University of Nebraska-Lincoln.
In an in vitrostudy conducted at the University of Toronto, the indigestible residue of Fibersym®RW was fermented using a human fecal inoculum. Fermentation products after 24 hours consist of gases as well as short-chain fatty acids like acetic, propionic and butyric acids. Of these acids, butyric acid is known to be protective against colon cancer.
Product designers often add Fibersym® RW to boost fiber content. Two nutrient claims can be applied to food products with respect to the level of dietary fiber per serving size. A “good source of fiber” claim means at least 2.5 grams of fiber (but not more than 5.0 grams) per serving size. Nutrition Facts panels in food packages do not normally report fractional numbers, so a “good source of fiber” will be seen as 3 grams or 4 grams of fiber per serving size. Another nutrient claim is “excellent source of fiber”, which means that a serving size of a given food will deliver at least 5.0 grams of fiber per serving size. It should be noted that serving size differs among consumer food products. FDA defines serving sizes in the Code of Federal Regulations (21 CFR 101.12).
Knowing that Fibersym®RW delivers a minimum of 85% total dietary fiber, product developers can easily calculate the level of Fibersym®RW addition for a “good source” or “excellent source” of fiber claim.
Current daily consumption of fiber among U.S. consumers is in the range of 13-17 grams. The statistics on resistant starch is even lower. The amount consumed in the U.S. is 3-8 grams per day based on a 2008 survey. Both values are lower than the recommended daily intake of 25-38 grams of fiber, which each of us should consume every day. The threshold for regularity is 23 grams of fiber consumed per day.
This is a difficult exercise. One can first look at the Nutrition Facts panel and determine if the level of fiber meets the nutrient claim of “good source” or “excellent source” of fiber. If it does, the next information to look at is the list of ingredients. If the ingredient list does not contain any significant source of fiber from sources such as cereal brans, inulin, soy fiber, cellulose, etc. and “modified wheat starch” is a prominent ingredient, then the probability is high that this particular product contains Fibersym® RW.
Most commercial food applications of Fibersym®RW are in the bakery product category. Some examples are white breads, hot dog buns, hamburger buns, English muffins, bagels, flour tortillas, breakfast cookies, blueberry muffin bars, banana muffin bars, oatmeal raisin cookies, oatmeal chocolate chip cookies, double fiber breads, light breads, cheese crackers, pretzels, pizza and bakery mixes.
In the pasta category, Fibersym®RW is formulated in penne rigate, rotini, spaghetti, macaroni elbows and pasta mixes.
Processed foods like deli ham and turkey lunch wraps, turkey and bacon club lunch wraps, breakfast wraps, and pouch potatoes contain Fibersym®RW.
Fibersym® RW has a fine particle size. Typically, 95% of Fibersym® RW passes through a # 200 Sieve (USA Standard Testing Sieve; ASTME 11 in which the # 200 sieve has 75 micrometer openings).