There was a time when producing nutrition-oriented bakery products was a matter of simple subtraction. Formulators took out fat and sugar to support the "reduced" or "low" claims manufacturers needed to appeal to a growing health-conscious constituency. Now this segment is placing even more demands on baked food manufacturers, and the less-is-more approach will no longer suffice. Subtraction is replaced with addition, and formulators are adding as much as they can to products to support significant source claims. Both probiotics and prebiotics are becoming key additions, bringing more function to a wide variety of baked foods.
PRO VS. PRE. Before manufacturers can start reformulating, they must understand the differences between prebiotics and probiotics, and how these ingredients can be incorporated into various baked foods.
The Joint FAO/WHO Working Group Report on Drafting Guidelines for the Evaluation of Probiotics in Food defined probiotics as "live microorganisms which when administered in adequate amounts confer a health benefit on the host." More simply put, probiotics are cultures of bacteria living in the human gut that are healthful for normal intestinal function. Probiotics can prevent harmful bacteria from causing disease.
Like many bacteria, probiotics are heat sensitive, making them difficult to add directly to baked foods. However, if protected by encapsulation, probiotics can be added to snack bars, muffins and similar foods.
Encapsulation makes probiotics more resistant to acidity, compression, heat and shear. As encapsulation media, lipid materials with high melting points provide low-moisture conditions and an anaerobic environment for probiotics. Chocolate containing coated probiotics is ideal for probiotic addition because it will not require much additional processing and can be added to finished products in several ways.
Prebiotics differ from probiotics. They are defined as nondigestible food ingredients that may beneficially affect the host by selectively stimulating the growth and/or the activity of a limited number of bacteria in the colon. Thus, to be effective, prebiotics must escape digestion in the upper gastrointestinal tract and be used by the microorganisms comprising the colonic microflora. Another way to look at it is, prebiotics are nutrients that probiotic bacteria use as fuel sources, including dietary fiber and carbohydrates. One way to remember is: Pro — O — are bacteria that Operate in the human gut. Pre — E — is what they Eat.
Synbiotics are foods that combine probiotics and prebiotics. Since the term alludes to a combination of the activity of both, it should be reserved for products in which the prebiotic ingredient compound specifically favors the probiotic bacterial strain used in the product. For example, a product that contains the prebiotic oligofructose and a probiotic bifidobacteria would fulfill the definition.
HEALTHY ADDITIONS. According to a study published in the February 2001 issue of American Journal of Clinical Nutrition (Vol. 73, No. 2, Supplement Pages 361 to 364), numerous health effects are attributed to these "friendly" intestinal bacteria known as probiotics. Many different studies document that probiotics lower the frequency and duration of diarrhea associated with antibiotics, rotavirus infection, chemotherapy and, to a lesser extent, traveler’s diarrhea; stimulate humoral and cellular immunity; and decrease unfavorable metabolites, for example, ammonium and precarcinogenic enzymes in the colon.
Other studies provide evidence of the health effects of probiotics for reduction of Helicobacter pylori infections, reduction of allergic symptoms, relief from constipation and irritable bowel syndrome, increased mineral absorption (calcium and magnesium) to improve bone density and stability, and cancer prevention. All these effects cannot be explained by a unifying hypothesis based on a single quality or mechanism, so more research is needed to understand the health properties of pro- and prebiotics.
The beneficial influence of certain living bacteria consumed as part of foods has been known for more than 100 years. But it was not until recent decades that new knowledge has brought intestinal microflora into the spotlight. In Europe, the largest group of functional foods consists of probiotic, prebiotic and synbiotic foods targeted to improve the gut microbiota and, by doing this, improve human health and well-being.
Japan’s unique Foods for Specified Health Use (FOSHU) category came into effect in 1993, and more than 500 different items have qualified based on a list maintained by the Japanese Department of Health of approved foods and ingredients for which enough scientific evidence supports their health claims. The FOSHU list includes 70 different nondigestible carbohydrates (dietary fiber) and 50 probiotic organisms. Foods containing probiotics comprise the largest segment of Japan’s functional foods market.
FORMULATION CHALLENGES. Prebiotic fibers, because of their ability to aid in digestion, are probably the most common form of prebiotics found in baked foods. Prebiotic fibers can come in forms such as resistant starch, inulin and fructooligosaccharides (FOS). They generally aid beneficial probiotic bacteria such as Bifidobacteria and Lactobacilli already in the human gut. Research suggests that 5 g of inulin a day stimulates growth of helpful gut bacteria, which leads to a healthy digestive system. Resistant starch has excellent prebiotic properties and is well tolerated by the body, causing considerably fewer side effects than other fermentable fibers.
Despite the health benefits associated with fiber, formulators might find challenges working with these ingredients. It may be a balancing act between adding enough to achieve the functional properties without a negative impact on the sensory characteristics of the product. In addition, to perform as a prebiotic, the ingredient should be able to withstand, first, the rigors of food processing and, second, digestion in the upper gastrointestinal tract.
One formulation challenge to overcome is that many, but not all, forms of fiber absorb large amounts of water. This may affect the quality of the final product as well as the processing parameters. When insoluble fibers are used, moisture levels and mix times should be increased to account for the fiber’s ability to trap moisture. In addition, increased baking times and temperatures will be needed to drive off the lingering moisture.
Also, some materials such as inulin may be hydrolyzed slightly by yeast enzymes. The best choice for yeast-raised products would be a high-temperature-process inulin, which also allows controlled water uptake in high-fiber bread with improved dough handling.
Because probiotics often release gases as by-products of their fermentation, excessive fiber in a formulation can run the risk of gastrointestinal discomfort (bloating). A good guideline is to stay within 2.5 to 5 g of prebiotics per serving.
Longer chain length for the polysaccharides comprising prebiotics means longer fermentation times in the gut, and this improves tolerance by the consumer. Formulators can use a combination of fiber sources to aid tolerance. Arabanogalactan, a nonstarch polysaccharide found in many forms of dietary fiber, ferments very slowly, as does polydextrose. Also, tolerance is a function of the finished product’s water activity, so high-solids (low-moisture) products such as snacks, biscuits and breads that contain high levels of dietary fiber will be better tolerated than beverage products with equivalent fiber content.
See "A Prebiotic Guide" on Page 34 to find out specific prebiotics available, the sources of these nutrients, their properties and how they are marketed around the world.
NEW FORMULAS. Changing traditional baked foods and snacks into functional foods isn’t as simple as adding extra ingredients; food manufacturers must take a lot into consideration before altering formulations. Because they are affected by high baking temperatures, probiotics are commonly added after the baking process is complete. A probiotic could be mixed into the creamy filling inside a sandwich cracker or biscuit. Probiotics can also go into chocolate toppings or coatings, yogurt toppings or coatings, or oil-based coatings. Formulators need to work with environments that are friendly to the live probiotics such as low water activity, high protein level, low sugar level and higher fat level.
Before choosing a particular functional ingredient such as probiotics and prebiotics for bread, bars, cereal, pasta or other grain-based foods, food manufacturers need to consider taste, affordability and appropriate functionality.