Inulin and that “Gut” Feeling
Before inulin found fame on the U.S. low-carb circuit, it was making regular appearances on the ingredient labels of Stonyfield Farm (Londonderry, N.H.) products and other dairy manufacturers who nourish their probiotics with prebiotic fibers.
Over a span of five years, products by Stonyfield Farm have evolved to include prebiotic inulin in the company's entire line of yogurt and cultured soy products. “Our objective is to continue to provide as many healthy components as possible, through yogurt and cultured products, without sacrificing their quality,” says Kasi Reddy, vice president of R&D and quality assurance at Stonyfield Farm.
Stonyfield's yogurts contain six live and active yogurt and probiotic cultures, which include Bifidobacteria. Inulin selectively stimulates the growth of this beneficial microflora, creating the ideal symbiotic yogurt products. “We are big advocates of symbiotic products,” says Reddy. “Inulin has a perfect synergy with the probiotic bacteria we use.”
Symbiotic food products contain not only health-promoting microorganisms but also the prebiotic fibers that selectively stimulate the growth of lactic acid bacteria. “The health of the large intestine is generated almost exclusively by fermentable fibers (like inulin) that act as a food source for the health-promoting bacteria,” concurs Bryan Tungland, vice president of scientific and regulatory affairs for a global inulin supplier.
The relationship between inulin and bifidobacteria results in the production of short-chain fatty acids (SCFA), which creates a low-pH environment in the digestive system and helps with calcium and magnesium absorption, explains Reddy. This low-pH environment restricts the growth of disease-causing bacteria in the digestive system.
“Stonyfield's launch of Yo Baby drinkable yogurts with inulin has been a huge success,” states Mark Izzo, director of science and technology at another global inulin supplier. Of late, more U.S. products containing inulin, like those at Stonyfield Farms, also have assumed the challenge to make calcium absorption efficient in the gut. Both launched within the last year, Tropicana Smoothies (Bradenton, Fla.) and Yoplait Nouriche (General Mills, Minneapolis) also contain inulin for similar purposes.
Fermentable dietary fibers, in general, set the stage for the entire health of the human body. The fermentation of inulin produces high levels of propionic acid, the primary SCFA used by the liver to reduce serum triglycerides and serum cholesterol in the blood. “Not only does calcium absorption take place in the large intestine, but 65% to 70% of our immunity is located in our large intestine,” informs Tungland. In addition, colorectal health provides a preventive mechanism for autoimmune re-expression.
The USDA allows for structure function claims provided an efficacious dose of inulin is consumed based on clinical or literature references and inulin is a part of the nutritional make up of the food. “Some of the structure function claims that could be made with inulin include, 'helps promote the growth of bifida bacteria;' 'helps promote healthy digestion;' and 'helps maintain healthy cholesterol levels,'” says Tungland. “With the exception of structure function claims regarding calcium absorption, for which higher inulin levels would be needed, most of the structure function claims about inulin fall into the 5g/day category,” says Tungland.
The Right IdentityHowever, inulin has seen a burst of popularity in the U.S. because of its functional properties that affect texture, body and mouthfeel. Many of those textural properties are based on the size of the inulin chain length. Inulin is a non-digestable fiber culled from a chicory root by a hot water extraction process, and then filtered based on chain length.
“One of the misconceptions that a lot of people have about inulin is that inulin, fructo-oligosaccharide (FOS) and oligofructose are all inulin,” says Robert Veghte, a business manager at a specialty fiber blend supplier. “They are right to a point, but there are differences between the products. You may be able to get away with using one product in one application, but you may need to use another in a different application.”
The difference between inulin and oligofructose is the degree of polymerization. “The correct inulin must be chosen for the food system the manufacturer is working in,” says Izzo. With or without a glucose terminal, inulin can consist of linked fructose molecule chains ranging from two to five fructose molecules, all the way up to about 50 to 60 molecules. Standard inulin chains average at about 15 molecules. Long-chain inulin and standard inulin work well in applications that use inulin to bind water. It is perceived to convey a fattier mouthfeel than short-chain inulin. The long-chain inulins provide structure, fiber and bulk fill, are able to sustain high temperatures and (depending on the chain lengths) can bind roughly four times more water than short chains.
The shorter chain length version of inulin, FOS is anything with a degree of polymerization (DP) shorter than 10. FOS comes in two forms created in two different ways. It naturally can be isolated from chicory root and then enzymatically hydrolyzed to shorter chain lengths. Alternatively, several single fructose molecules can be polymerized enzymatically to produce FOS. “The short-chain inulins provide humectant properties and elasticity when used with hydrocolloids like xanthan gum,” explains Tungland. Also known as oligofructose, or short-chain fructo-oligosaccharides, shorter FOS chains are sweeter and more soluble. In meats, medium-chain length inulin can represent properties of both long- and short- chain inulin.
Poly-dispersed inulin, which is the native inulin, is normally found in chicory root. “Typically, poly-dispersed inulin, a mixture of short-, medium- and long-chain inulin, is used in meat products,” says Tungland.
The difference in the health benefits of the shorter and the longer chains are dependent on each supplier's studies. “There are a number of different ways you can look at it. Overall, they all do the same things. It's just a matter of how much you need to eat. As far as intestinal health is concerned, shorter chains are generally linked with better or faster growth in beneficial bacteria,” says Veghte.
Low-carb ProductsAll fermentable dietary fibers have an effect not only on lipid metabolism but also on carbohydrate metabolism and inulin is no exception. Recently, inulin's popularity as a fat, starch and sugar replacer in U.S. weight-loss products has taken center stage over its original functionality as microflora chow. According to Izzo, inulin is being used in many low-carb baked goods, breads, cookies and muffins as an ingredient of choice for taste, functionality and nutritional reasons.
“Inulin is highly effective in low-carbohydrate food products because it provides elasticity to dough and baked products,” states Tungland. It works with protein and hydrocolloids to reestablish the film or food structure that is lost when protein and starch is removed from flour.
It is important for consumers and manufacturers alike to know that low-carb foods provide a vehicle to help diabetics and people trying to gain control of their weight, says Tungland. “[However,] the ingredients such as the dietary fiber [like inulin] are really the keys to health. It's not that the food is low-carb or sugar-free. It's the fact that they contain higher levels of fermentable fiber in specific ratios that provide the keys to gastrointestinal health, heart health, increasing immunity and bone health,” informs Tungland.
For instance, inulin, when fermented with resistance starch, results in high levels of butyric acid. Butyric acid is used almost exclusively by the lining of the large intestine and acts as a differentiating agent to convert pre-cancerous colon cells to normal cells. In regards to heart health, “Through the fermentation process, you have a reduction in the formation of glucose and the increase in the formation of glycogen with a reduction of LDL (bad cholesterol),” says Tungland.
Sugar Replacement“In low-carb foods and sugar-free systems, polyols are often used in combination with inulin,” says Izzo. Inulin is used in sweetener blends because it acts as a bulking agent during sugar replacement. “The mouthfeel that comes from the product is beneficial for bakery applications where you want a rich, thick, mouthfeel, especially when using it with sugar alcohols,” says Veghte.
“Generally, you have to add a sweetener to an inulin or an oligofructose if you are going to use it as a sweetener. It is not sweet enough on its own,” says Veghte. Also, inulin is not a non-nutritive sweetener. Depending on the supplier, the calorie content is usually around two calories/g as opposed to four calories/g of sucrose. “[The manufacturer should] look at each individual supplier's statement to obtain their calorie content,” suggests Veghte.
Some suppliers have oligofructose-based products that often are used as masking agents. According to Veghte, they cover up the taste of soy, whey protein, vitamins and minerals. “These products extend beyond the standard oligofructose product because they improve the flavor or sweetness profile of high-intensity sweeteners in order to give them a cleaner and better taste,” he adds.
Additionally, some consider them easier to use because they combine everything into one product. They act to mask sweeteners while also adding fiber. “It really depends on exactly what a manufacturer is looking for, but those products are one step easier. You don't have to add fiber, sweetener and flavor to cover up the sweetener aftertaste and then balance everything back out again. The supplier has already taken care of all that,” says Veghte.
Products like Entenmann's (Seattle) Carb Counting Chocolate Chip Cookies, launched March 2004, contain inulin blended with isomalt and acesulfame potassium, a combination that is said to enhance product flavor.
Humectant Properties“Inulin binds with water in any application where there is moisture,” says Veghte. Certain inulin suppliers have been given product- and production-specific GRAS approval by the USDA and the FDA to sell their inulin for use in meat products and analogs. Inulin adds lubricity and mouthfeel to meat analogs such as soy protein, tofu and vegetable protein.
“It allows you to have effective binding, elasticity and provide plastic character in meat products, which allows you to enhance meat and spice flavor, provide dietary fiber and reduce fat in meat applications,” says Tungland. Inulin has a lot of hydrogen bonds on the fructose polymer, which attracts water and facilitates the transfer of water to maintain the hydration of the protein.
“It doesn't release water when it is cooked. It gives you the moisture perception of meat when it is cooked, allowing the vegetable protein to have the lubricity, mouthfeel and hydration of animal meat,” explains Tungland.
In production of restructured poultry, consideration should be given to the efficiency of producing a homogeneous mixture, says Tungland. When inulin goes into a meat application, one is essentially injecting and rolling an inulin particle gel into the meat. “Injection processes typically take more consideration than tumbling processes to incorporate inulin. Injections cause layering. Tumbling is a more efficient process. The little pockets of white paste, noticeable in layering, do not exist when you tumble, which allows for more mixology and less potential for layering,” informs Tungland.
“Inulin provides hydration efficiency to hydrocolloids like xanthan gum to synthesize a fat like mouthfeel and texture when used together. Inulin is a hydration facilitator making hydrocolloids and proteins work together more efficiently to make meat products lower in fat,” says Tungland. However, they still are representative of the full-fat flavor profile.
Water binding also assists with shelflife extension in bakery as well as with bars and meat products. “Inulin is unique in how it attracts water preferentially to other components like starch.”
Like with most dietary fibers, solubility can pose a problem. “You cannot use inulin in something like coffee syrup. It won't stay in solution, but you could use oligofructose,” advises Veghte. Some suppliers produce inulin that can dissolve completely in clear beverage applications.
“Inulin is generally stable for baking, but it will break down some when heated. When inulin breaks down, the fructose chains break apart, “Which basically means you just added a little bit of fructose to the product,” says Veghte. The product will usually break down very rapidly in very acidic solutions under pH 3.5. “If you stick it in a normal soda it will break down to fructose. Although it won't reduce the amount of bulk, it will reduce the amount of fiber in the product,” warns Veghte.
“Whenever you reformulate a product, the goal is to keep the existing attributes intact and provide the consumer with a consistent quality product,” says Reddy. Inulin is suitable for just such a task. “Our objective was to provide as many healthy components as possible through the yogurt--without sacrificing the taste. Inulin not only matched the control, but enhanced the body and texture properties [of our products].”
Going GlobalDespite evidence that live and active cultures contribute beneficially to digestive health the, “U.S. yogurt market is still undeveloped compared to other parts of the world,” says Stonyfield Farm's Reddy. “Consumer perception of the use of gut health in general is way behind Europe and certainly way behind Southeast Asia and Japan. It has a lot to do with our culture. We're very averse to the social aspect of fermentable fibers and what they do, and some of the metabolites like gas that get produced,” observes Tungland. In fact, the low-carb caravan has, in many ways, brought inulin to the States despite the fact the low-carb trend is not as strong in the rest of the world as it is in the U.S.
According to Mintel's GNPD, as of May 19, 2004, there were 78 launches for food products listing inulin as an ingredient between Jan. 2004 and May 2004 in all regions of the world--except for North America. Salutello brand Probiotic Salame by La Felinese Salumi (Parma, Italy), Tropicana's Pure Premium Fibres Juice (Brussels, Belgium) and Goldhand Vertriebsgesellschaft's Tip brand Frühstücks Müsli Breakfast Cereal (Düsseldorf, Germany) were among that list. Of them all, only one, EnfaMom Dietary Supplement Drink Mix (Bristol-Myers Squibb de Mexico) for pregnant and nursing mothers, makes a low-carb claim. Conversely, in North America, there were 44 inulin-related launches within the same time period, of which 27 make low-carb claims.
All gastrointestinal-related disorders can be attributed--to some extent--to low-fermentable fiber diets. “If U.S. consumers actually knew that…most autoimmune diseases like Crohn's disease, rheumatoid arthritis and diabetes have a link to diets low in fermentable fiber…they would be a little less concerned about their bowels and more concerned with the health-promoting properties of natural fibers like inulin,” presumes Tungland.