Formulating in Fiber

While fiber-enhanced product introductions have increased significantly in past years, a recently released study conducted by the National Institutes of Health (NIH) and the American Association for Retired Persons (AARP) may further accelerate that trend. The study identified a link between high-fiber diets and lower risks of death, not only from heart disease, but from infectious disease and respiratory illnesses, as well. Participants who consumed the highest levels of fiber experienced a significant reduction in mortality from all causes compared to those who ate the lowest amount. The overall benefit is greatest in diets high in fiber from grains.

Fiber can be added at 3-10% of total formula in a wide variety of baked products. Depending on sugar, fat content and other considerations, a front panel claim “a good (or excellent) source of fiber” may be made. Even for products where a claim cannot be made on the front panel, the fiber grams per serving listed in the nutritional panel on the package can still communicate a nutritional benefit, as more consumers preferentially select products with higher fiber levels.

When adding a fiber or resistant starch ingredient to a product for nutritional reasons, additions of 5-10% of total formula may be required to meet marketing objectives. It is often best to choose a fiber with minimal functionality in the food. This permits a larger amount of fiber to be added, with minimal effect on structure or texture of the product. When insoluble fibers are used, a fiber with low water-holding capacity would meet these criteria. For soluble fibers, a fiber that contributes low viscosity in solution is beneficial.

However, beyond nutrition, fiber can provide many functional benefits. In this case, the specific fibers will be selected for maximum functionality for the desired benefit. Depending on the specific fiber selected, fiber can serve as an emulsifier, aiding in aeration in the batter stage and the development of a controlled cell structure in the finished baked product. Fiber can provide a volume enhancement in the finished product. This may permit a cost reduction, by providing the same size product at a lower net weight. It may also serve to reduce calories/serving by the same mechanism.

Insoluble fibers with long particles can establish fibrous networks in the product, giving it dimensional stability. This can provide structural benefits in “soft” systems, such as bread, by preventing excessive softness. In cookies, fiber can be a tool for spread control. Significant resistance to breakage and cracking can be imparted to fragile baked goods, such as ice cream cones, pretzels, crackers, cookies and bars. Extruded products, such as cereals, pasta and extruded snacks; and crisp fried snacks, such as tortilla chips and structured potato chips, can also benefit from the same mechanism. This functionality can also enhance tortilla and wrap quality, by providing resistance to failure during use; and hot dog buns and flat bread, by increasing hinge strength.

Insoluble and soluble fibers have the potential to increase moisture retention through baking and shelflife. This moisture increase can help increase fresh shelflife for breads, rolls and buns by slowing staling reactions. The water-holding characteristics of fiber can be utilized to provide improved freeze/thaw properties and ice crystallization control for frozen baked goods. However, care must be exercised, when increasing finished product moisture contents, to assure microbiological stability of the finished product is maintained. Also, when moisture contents are altered, moisture-related reactions, such as Maillard browning, crystallization, etc., may be affected. This may require some other adjustments in formula or process to compensate.

Volume increases, improved structural integrity and increased moisture retention are clearly identifiable, quality benefits that result from fiber addition. But, these same quality benefits may also translate into substantial yield improvements in manufacturing or distribution, which ultimately drive lower product costs.

Consequently, to optimize a fiber-containing food product for both nutrition and functionality, one would select specific fibers and levels based on functionality first, then add the rest of the fiber required to meet nutritional objectives—via fibers that have minimal functional effect on the texture or structure of the food product. 

Fat Reduction and Trans Fat Replacement
Reducing the fat content or changing the fat source in baked goods can drive a range of textural issues. Again, fundamental understanding of the food system can provide approaches to resolve these problems.

One instructive example comes from fat-free formulations. When fat is reduced or eliminated from a food product, it must be replaced with another ingredient. In cakes, it was replaced by sugars. This led to an issue with collapse after baking, driven by insufficient structure caused by the increase in gelatinization temperature for wheat starch (caused by increased sugar concentration). Understanding the basic sources of structure, as the cake baked, led to the solution. The missing structure was replaced with pregelatinized or lower gelatinization temperature starches.

Other approaches focus on changing the composition of fat, rather than reducing the level. Trans fat replacement has been an area where a detailed understanding of baked goods structure, from the beginning to the end of the process, has been a key to success.

Shortening suppliers can first be relied upon to provide materials that meet the nutritional challenge. For systems where fat solids are not critical to acceptable texture, oils can replace plastic shortening. In some of these cases, the replacement is direct. For other products, adjustments must be made to replace the structure provided by the fat solids. Some products need to be reformulated to match the dough rheology to the greater fluidity of oil. The solids in trans-containing shortenings may provide structure early in baking, which is lost when oil is used. When this occurs, other ingredients, such as starches, fibers, hydrocolloids or emulsifiers, can be employed to replace the missing structure during that critical part of the process.

For other systems, oil cannot replace the functionality of trans-containing plastic shortenings. Oil suppliers offer a wide range of plastic shortening products to solve the problem, and developers need to choose the product that comes closest to matching the original shortening. Options include fully hydrogenated, hard stock blended with traditional oils, trait-enhanced varieties or alternative vegetable oils, which naturally possess higher solids contents. Emulsifiers are also added to some of these blends, providing a wide range of performance characteristics. Interesterification is also used to tailor specific melting profiles for certain difficult applications that warrant this relatively costly approach.

However, the alternatives seldom perform identically, leaving specific problems to be resolved. Again, most of these are to be structural in nature. Where palm oil or hard stock is incorporated into the fat, there may be mixing problems. These can be resolved by altering order of addition, mix procedures or processing temperatures. During dough processing, the new shortening may flow slightly differently from the original, necessitating adjustments in dough rheology to match the new shortening. For some products, the problems can be traced back to differences in structure during baking, specifically due to differences in the melting curve for the new shortening. In these cases, a detailed understanding of the specific problems during baking will guide the best solutions. The use of non-fat, structure-building ingredients, such as proteins, hydrocolloids, fibers and starches, may be helpful. If the problem is spread in cookies or other baked goods, pH, flour type, sugar level, emulsifiers and fibers can all help provide good solutions. When the traditionally optimum shortening is no longer nutritionally acceptable, there is potentially more than one way to replace the functionality.

Pressures continue to optimize the fat contents of food products. The 2010 U.S. Dietary Guidelines encourage the avoidance of trans fats and the reduction of saturated fat to 10% of calories or less. The replacement of saturated fat with poly- or monounsaturated fat is encouraged, and increases of sugar or refined grains are discouraged. With Wal-Mart targeting the elimination of remaining industrial trans fats and reduction of added sugars by 10% from packaged food products that it sells by 2015, there will likely be another round of reformulation for some products. Presumably, trans fats would have been eliminated in the previous reformulation, if this were easily accomplished. The approaches outlined above will need to be extended to eliminate the remaining trans fat in products, while also delivering to other the prescriptions in the Dietary Guidelines.

Nutrient-dense Products
This is an arbitrary title for product concepts that are increasing in popularity. Nutrient-dense products are loaded with multiple macronutrients to provide certain consumer benefits. One popular area includes “morning products,” which seek to provide satiety and manage blood glucose levels. Examples include cereals, breads and bars with high fiber and high protein, possibly with other fortifying nutrients.

The formulation problem with this category of products is the exclusionary principle. If macronutrients, such as protein and fiber, are increased, what can be removed? Here, a three-step method proves useful.

The first step is to preferentially choose multi-functional sources of macronutrients, if possible. Here, the ingredient provides two or more very different functionalities required by the product. An excellent example of this is inulin or oligofructose, which can provide fiber, sweetness and humectancy with one ingredient. As described earlier in this article, certain fiber ingredients can serve multiple functions. Proteins can also be selected to provide other specific product requirements, such as film forming, browning, specific flavors, etc.

The second step is to use the minimum amount of highly functional forms of ingredients to deliver the desired functional benefits. After these ingredients have been applied to the formula, the third step is used to deliver the remaining quantity of macronutrients.

The third step is to add the remaining required amount of a low-functionality form of macronutrient ingredients to minimize the extraneous functional effects on the food system. For example, proteins and fibers can be great water-absorbing ingredients. However, if the objective is to load the system with a high level of fiber, protein or both, and they also absorb a high level of water, this can make formulation more difficult. In this case, it might be best to specify proteins and fibers which deliver the lowest water-holding capacity possible. This will minimize the impact high levels of these ingredients have on the system. The same logic applies to other functional aspects for proteins and fibers. In general, if the goal is to maximize the level of these ingredients in a product, in this third step, look for the sources with the least product functionality.

Maximizing a baked goods matrix for both great taste and great nutrition is more possible today than ever before. The best tools are a clear understanding of the structures and ingredient functions in the food system; carefully chosen ingredients; and some good problem-solving. pf