Not that long ago, the focus of the grain-based food industry’s dialog about fiber ingredients was limited to insoluble fiber, the type predominantly found in whole grains and starch.
But there is an entire other broad class of fiber that has application in bakery and snack foods — soluble fiber. Typical soluble fiber ingredients are fructooligosaccharide (FOS), gum, inulin, polydextrose and resistant maltodextrin, among others.
Soluble fiber has many claims to fame including the ability to lower blood cholesterol by trapping dietary cholesterol and bile acids as they pass through the gastrointestinal tract, thus helping the body eliminate cholesterol. Soluble fiber also slows carbohydrate digestion and absorption. In theory, this might help prevent wide swings in blood sugar levels throughout the day and have an impact on the development of adult-onset diabetes. And in the past decade or so, soluble fiber has become recognized as a prebiotic.
WHAT’S A PREBIOTIC?
A prebiotic is something that provides an ecological advantage to a specific group of probiotic bacteria growing in the colon. So what are probiotics?
The term probiotic is derived from Greek and means "for life." Probiotics are best described as live microorganisms that improve health or wellbeing by modifying the intestinal microflora. In most, but not all definitions, the probiotic must survive passage through the stomach, take up residence in the gut and have a positive effect on health.
Probiotics have been studied for their ability to stimulate the immune system, to prevent diarrhea, to reduce gut colonization by pathogenic bacteria, to exhibit anticarcinogenic activity and to reduce serum cholesterol, lactose intolerance and allergic reactions to foods. However, not all probiotics have the same potential health benefits. Probiotic effects vary from strain to strain within the same species, and not all strains have been studied to evaluate their potential health benefits.
Prebiotics, in essence, are an energy source for probiotic bacteria. In other words, probiotic bacteria digest prebiotic fibers. The rationale for humans to consume prebiotics is that probiotic bacteria already resident in the gut are "given a boost" to assure a healthy microflora community and maintain positive health benefits. Since prebiotics are more stable in food systems than probiotic microorganisms, it is becoming quite common to see prebiotics added to all types of food formulations including bakery and snack foods.
The fact is, "all fiber acts as a prebiotic, some just more so than others (for example, soluble vs. insoluble fibers)," said Dennis Gordon, Ph.D., professor emeritus, North Dakota State University, Fargo, ND. "The search for novel prebiotic fibers that promote growth of specific desirable probiotics is ongoing."
As mentioned, the soluble version of fiber is typically what is considered a prebiotic; however, recent research reveals that certain insoluble fibers have prebiotic tendencies, too.
"Research has shown that highamylose maize starch granules can act as a delivery system for probiotic bacteria," said Rhonda Witwer, business development manager, nutrition, National Starch Food Innovation, Bridgewater, NJ. "Probiotic bifidobacteria were able to adhere to the amylose starch granules and hydrolyze the starch during growth. The study concluded that high-amylose maize starch granules contributed to enhanced survival of select strain of probiotic bacteria.
"In other studies, Hi-maize 5-in-1 Fiber was shown to act as a carrier for probiotic bacteria in yogurt," Ms. Witwer added. "By having Hi-maize and probiotics in the same system, formulators are able to develop a symbiotic product, which allows maximum benefits in the gastrointestinal system."
PROBIOTIC OUTSIDE DAIRY
Although probiotic bacteria are naturally present in the gut, many people feel it necessary to supplement them through their diets. Dairy products such as yogurt, as well as dietary supplements, are currently the preferred delivery vehicle for probiotics, but technology may enable bakery products to be probiotic carriers, too.
How might baked foods, with their high-heat processing method, host probiotics, which are heat sensitive? "Our proprietary technology encapsulates probiotics, protecting them from deleterious environmental factors," said Cliff Caron, vice-president, bakery product development, Lallemand/American Yeast, Montreal, QB. "Basically, a matrix of food-grade vegetable fatty acids is sprayed onto freeze-dried probiotic cultures. This non-water-soluble coating enables probiotics to be added to fillings or frostings, which are not exposed to baking temperatures.
"If the formulation also includes a prebiotic, then you can get both into the gut at the same time," he added.
FORMULATING WITH FIBER
These research findings and innovations all have great potential down the road for the baking industry. For immediate application, however, the tried-and-true method of adding soluble fiber to probiotic-containing foods can create a symbiotic product. Or in the case of grain-based products, fortification of foods with soluble fiber provides energy to bacteria inherently present in the colon. There are a variety of soluble fibers available to bakers and snack food manufacturers.
NutraFlora short-chain fructooligosaccharide (scFOS) from GTC Nutrition, Boulder, CO, provides an easy way to bring fiber enrichment and flavor enhancement to a variety of bakery and snack products. "In addition, a small inclusion of NutraFlora provides valuable prebiotic benefits, such as increased mineral and nutrient absorption, enhanced immunity and optimal digestive function," said Linda Douglas, Ph.D., GTC’s scientific affairs manager. "NutraFlora is produced from cane or beet sugar using a patented process, non-GMO ingredients and a traditional natural fermentation method that allows the retention of the positive attributes of sugar such as excellent solubility and a sweet flavor profile. And since NutraFlora is soluble prebiotic fiber, it has no glycemic impact.
"NutraFlora supports both of the major probiotic gut microflora species — bifidobacteria and lactobacilli," she continued.
Hilary Hursh, food and nutrition scientist, Orafti Active Food Ingredients, Malvern, PA, discussed the company’s prebiotic ingredients. "Raftiline inulin is extracted from chicory roots and is composed of chains of fructose units. Raftilose oligofructose is obtained by partial hydrolysis of inulin," she said. "Human studies have shown that daily intake of small amounts of inulin and oligofructose stimulates the numbers and activity of beneficial bifidobacteria in the human colon. Furthermore, studies have shown that oligofructose and bifidobacteria have a protective effect against some intestinal disorders. This means that the bifidogenic effects of oligofructose and inulin can have important implications for health and well being."
Orafti also markets an enriched inulin, Raftilose Synergy1, which has been shown to increase dietary calcium uptake by up to 20%. "It is effective at a dosage of just 8 g per day, which equates to 2 g per serving, a very reasonable amount to use in food formulations," Ms. Hursh stated. "This could have important consequences for the prevention of osteoporosis."
A new large-scale scientific study found that older people, can benefit from foods containing Raftilose Synergy1. "As people age, the number of beneficial bacteria in their intestines declines, putting them at greater risk of disease," Ms. Hursh said. "The results of this new work show that Raftilose Synergy1, combined with probiotics, helps reverse this process, improving intestinal function and well-being by keeping the important digestive microflora healthy."
Inulin is readily added to grainbased formulations because it does not bind water. It also has a clean, neutralto-sweet taste.
Minneapolis-based Cargill Health & Food Technologies markets Oliggo-Fiber inulin. Natural chicory fructan inulin from Cargill’s inulin supplier, Cosucra Group Warcoing, was used in a recently published study by Kyung Hee University, Seoul, Korea. Results revealed that two 4-g servings of Oliggo-Fiber Instant inulin may increase calcium uptake in post-menopausal women by as much as 42%. These findings echo previous studies on inulin’s potential calcium retention benefits, which are thought to be a result of the ingredient’s ability to lower pH within the colon, thus improving calcium’s solubility.
Calcium absorption is of particular importance to post-menopausal women, who are at higher risk for osteoporosis, especially if they don’t take hormone replacement therapy. "Consumer awareness of the importance of bone health has led to the growing popularity of calcium-fortified products," said Steve Snyder, vice-president at Cargill. "Now science supports the incorporation of Oliggo-Fiber inulin into calcium-enriched foods with massmarket appeal because it may boost calcium absorption during critical times of calcium need such as the pre-teen and post-menopausal years." Grain-based foods are proven delivery vehicles for calcium, making them attractive for both calcium and inulin fortification.
Digestion-resistant maltodextrin is another category of soluble fiber with prebiotic tendencies. An example is Fibersol-2 developed by Matsutani America, Inc., Decatur, IL, and marketed by Matsutani and ADM Specialty Ingredients, also of Decatur.
"Fibersol-2 is a unique product. It has the lowest viscosity of all available soluble fibers. At normal usage levels, it simply does not interfere with final product viscosity," said Mark Matlock, senior vice-president, food research at ADM.
In bakery products, Fibersol-2 can be incorporated with other dry ingredients at fairly high usage levels. "In fact, it can be dropped into nearly any product with only minimal changes to the formulation," Mr. Matlock said. "And if you are just a few grams under being able to make a fiber claim, a small addition of Fibersol-2 will bring that fiber up to claim level.
"Digestion-resistant maltodextrin does not interfere with water function in bakery systems,’ he continued. "Many other soluble fibers absorb water — sometimes as much as three to 12 times their weight in water. When a fiber takes up moisture, it often changes the bake time and the formula because more water is needed. With Fibersol-2, addition is invisible."
Polydextrose is an example of a soluble, prebiotic fiber that can be used in a variety of bakery applications. As with most fiber sources, when using polydextrose in a bread application, there may be a need to slightly increase water and vital wheat gluten depending upon the amount of added polydextrose.
Polydextrose is an attractive prebiotic fiber choice to many bakers. "Litesse polydextrose is one of the more effective prebiotics on the market today because it has a sustained effect throughout the entire intestine, and it is well tolerated," said Donna Brooks, product manager, Danisco Sweeteners, Ardsley, NY. "Not sweet in itself but ideal for use in combination with intense sweeteners, Litesse has a superior clean taste, which means it can be used in high proportions for up to 50% calorie reduction even in products with sensitive flavor systems."
There are numerous other ingredients that are high in fiber, and researchers are continually investigating their prebiotic tendencies. As Florian Ward, Ph.D., vice-president of research and development, TIC Gums, Belcamp, MD, noted, "Water-soluble gums contain at least 80% soluble fiber."
As consumers continue to seek out dietary solutions to health and wellness, prebiotics will play a more important role in food formulating. "Many of the trends concerning health and wellness that have evolved over the past 16 years or emerged in recent years are converging today to reshape how consumers think about their health and the healthy choices they make for themselves and for their families," said Linda Gilbert, president of HealthFocus International, St. Petersburg, FL. "This is a critical time for brands and companies to consider their strategies and how they align to where shoppers are headed in their thinking and behavior toward health."