Viability vs. Process
September 1, 2008
by Laurie Gorton
Nutrients are not all alike when it comes to their ability to stand up to the rigors of food manufacturing processes. Some exhibit good stability, but others require more protection to enable them to deliver their benefits to the end user — the consumer. Millers, bakers and breakfast cereal makers effectively solved the problem of nutrient viability for the vitamins and minerals involved in the mandatory enrichment of their products.
The scope of fortification, however, has enlarged greatly in recent years. Consumers interested in pursuing healthy lifestyles want foods that support their choices. Improved nutritional value through fortification not only means added vitamins and minerals but also inclusion of nutraceuticals — food ingredients new to many applications. And it’s not just bread and breakfast cereal that get fortification but also snack foods, nutrition bars and a myriad of other food categories.
Some observers differentiate between fortified and functional foods, defining “fortified foods” as those primarily intended to help prevent nutritional deficiencies and giving the name “functional foods” to those that go beyond nutrition to prevent and treat disease and improve overall health status. Both categories, however, get their effects from ingredients added to formulations.
ADVANTAGE TO FOOD. As consumers widen the focus of their attention on nutrients, they also make decisions about the formats which deliver these nutrients. Dietary supplements offer many of these materials, but labels can be confusing, especially disclaimer required by the Dietary Supplement Health and Education Act of 1994.
Also, variability of active content can be a concern. The good news is that nutrients delivered through foods are being found to be more bioavailable than those supplied by supplements.
A recent study, for example, verified such vitality for vitamin E in the form of alpha-tocopherol consumed in ready-to-eat (RTE) breakfast cereal fortified at 30-IU and 400-IU per serving vs. 400-IU capsules. Researchers from the Linus Pauling Institute, Oregon State University and Bell Institute of Health and Nutrition found that at the lower level in the cereal, vitamin E was six times more bioavailable than in the supplement; at the higher level, it was 26 times more available.
VITAMIN SURVIVAL. Vitamins vary in stability, with vitamins A, C and folate particularly sensitive to loss during processing and storage.
Fat-soluble vitamins as well as carotenoids and tocotrienes are subject to autocatalytic (auto-oxidation) processes similar to those that affect unsaturated fatty acids. Light, atmospheric oxygen, metallic ions (especially iron and copper) and free fatty acid radicals are all risks. With the exception of vitamin K, thermal processing diminishes fat-soluble vitamins, and the water activity (a ) of the system also has an increasingly deleterious effect as it increases.
Coating of fat-soluble vitamins will limit their exposure to degradation forces, and food additive antioxidants such as BHA, BHT or alpha-tocopherol (vitamin E) can be included in the coating to provide additional protection.
Some water-soluble vitamins are susceptible to oxidation, notably thiamin and cyanocobalamin (vitamin B12). In general, the more exposure of such vitamins to excess water, the greater the potential leaching effect. Vitamins stable in the acidic pH range include ascorbic acid, niacin, free folacin and thiamin. Those lost more readily under alkaline conditions include thiamin, biotin, free folic acid, pantothenic acid and ascorbic acid. Biotin and pantothenic acid are most stable at pH 7.0.
L-ascorbic acid (vitamin C), another important watersoluble vitamin, oxidizes easily, which is the basis for its use as a flour maturing agent and dough improver. Other factors affecting vitamin C survival include exposure to heat, increased pH, moisture and copper or ferrous salts. While bakers advantageously use ascorbic acid for its flour improvement function, if they want it to survive into the finished product as a nutrient, then an enrobed or encapsulated form must be selected.
Physical factors that prompt loss of vitality during processing and storage include light in the visible and near-ultraviolet range, with riboflavin and pyridoxine being examples. Temperature is another factor, although niacin, biotin, riboflavin and vitamin K are generally stable to heat. For example, at temperatures common to processing of RTE breakfast cereals, as much as 17% of initial vitamin B12 content is lost, with another 17% disappearing after one year of storage.
Fortification of an extruded or flaked product should be done during the final process, after extrusion, to limit the exposure of the added nutrients to heat and sheer. The sugar coating given many RTE breakfast cereals provides both sweetening and protection. Applying a sugar solution over food previously sprayed with a fortification mixture will improve retention of the nutrients during storage by providing good protection from oxidation attack.
MINERAL METHODS. Minerals, however, are not destroyed by heat, light, oxidizing agents or pH changes, but their bioavailability is subject to change due to processing methods. An interesting effect of calcium is that it tends to mask flavor and thus interfere with the desired flavor delivery of other food components. In general, the more bioactive the mineral form, the more likely it will be to cause a flavor, color or texture problem. Ferric ions will interact with fatty acids, causing rancidity. Thus, if a formulator wants to supplement foods containing omega-3 fatty acids with iron, an encapsulated iron is the best choice.
Sometimes, it’s the natural content of ingredients that gets in the way. Cereal grains, for example, are naturally high in phytic acid, or phytate when in salt form. Plants store phosphorus by forming these compounds and depositing them in their seeds, particularly in the bran. Phytic acid, which chelates zinc, magnesium and calcium, impairs the bioabsorption of these essential minerals. However, phytate and phytic acid can be broken down by the enzyme phytase, supplied by several species of probiotic bacteria. This conversion renders the metal ion complexes more soluble and more readily absorbed by the intestine. Probiotics must remain alive to perform their benefits, so encapsulating these microorganisms ensures their viability, too.
Not so incidentally, product developers should note that vitamins A, C and E are currently the focus of consumer interest for their physiological antioxidant qualities, believed to provide positive health effects ranging from inhibiting various forms of cancer to relieving hypertension.
FUNCTIONAL CHOICES. Nutraceuticals, or ingredients that function in the body to achieve desired nutritional effects, come in many forms: pieces, flours, liquids, extracts and powders. The sources of nutraceutical ingredients are varied and so is their performance during processing.
For many food categories, fruit is an ideal choice to call attention to healthy content by increasing the food’s nutritional profile without negatively impacting taste. The key to success is choosing the best fruit for the job, an especially critical decision for breakfast cereals. Most dried fruits are higher in moisture content than the cereal flakes, so the fruits will lose their moisture to the cereal. Because raisins keep their skins as the grapes dry, they tend to loose less moisture into their surroundings, according to the California Raisin Marketing Board, Fresno. CA. Raisins are also available in glycerated style, which further limits moisture migration.
Sweetened dried cranberries (SDCs) offer the texture of a dried fruit at even lower moisture content, according to Ocean Spray ITG, Middleboro, MA. The cranberries can be infused with other fruit flavors and with glycerin. Product developers seeking to add antioxidants to low-moisture foods such as RTE cereals would do well to choose SDCs. Cranberries are not only high in antioxidants but also proanthocyanidins, which are linked to improved gastrointestinal and oral health.
When considering a nutraceutical as a fortification ingredient, the product developer must determine its stability during preparation of the food. Inulin offers a good example. This dietary fiber has been demonstrated to boost calcium absorption and bone density while also helping lower body mass index (BMI) status of adolescents. In addition, inulin is very tolerant to extruder processing and the flaking process used to make many RTE breakfast cereals, according BENEO-Orafti, Morris Plains, NJ.
Choline has attracted growing attention for its health benefits, which encompass memory enhancement, mitigation of stress and improvement of liver function. Although choline occurs naturally in foods such as egg yolks and liver and is a mainstay in dietary supplements, interest in it as a fortification ingredient is growing, particularly for applications such as baked foods, nutrition bars and breakfast cereals, among others. According to Balchem Corp., New Hampden, NY, choline exhibits excellent stability in harsh processing conditions. It is easy to add to food systems and imparts negligible sensory effects.
Lutein, another nutraceutical of interest, is a naturally occurring carotenoid. It appears to play a crucial role in eye health and fits the “beauty from within” trend in food formulating. Obtained from marigold flowers, lutein is Generally Recognized as Safe (GRAS) for use in baked foods, breakfast cereals and a variety of other foods. It takes the chemical form of a fatty acid ester. This summer, Cognis, LaGrange, IL, introduced Xangold 8% WPD, a natural lutein ester in a water-dispersible powder form. In this form, it exhibits excellent bioavailability, according to the company because lutein esters are hydrolyzed and free lutein is readily absorbed.
Plant sterols, which have important heart health benefits, are amphipathic lipids, having mostly hydrophobic but polar regions. To improve incorporation of these nutraceutical ingredients into water-based systems such as doughs and batters, Cognis introduced Vegapure sterol esters in water-dispersible powder form. The sterol content of these powders ranges from 41 to 90%. When used in breakfast cereals, with typical serving sizes of 50 g, they provide sterol concentration of 0.8% per serving, and in nutrition bars, this content can reach 1.0% concentration in a 40-g serving. The sterol esters are also suitable for breads, cookies, muffins, pasta and snack foods.
PREMIX APPROACH. Custom nutrient premixes of functional ingredients are ideal for streamlining the development and production processes. As consumers and product developers alike stretch the definition of nutrients beyond vitamins and minerals, so have ingredient suppliers developed the technology to create custom blends tailored to the exact nutritional profile required.
For example, BioBlend 10-A from Caravan Ingredients, Lenexa, KS, provides 10 essential vitamins and minerals plus 5 g of fiber and 16 mg of omega-3 DHA per serving, when used in nutrition bars. At such usage levels, the blend provides 10% of the Recommended Daily Intake of biotin; folic acid; niacin; pantothenic acid; riboflavin; thiamin; vitamins A, B6, B12, D3 and E; calcium; iron; and potassium, plus fiber and DHA.
Premixes take the discussion of nutrient viability back to the experience of millers and bakers. The idea to blend these materials not only ensures proper dosing in the plant but it saves the processor labor, time and expense.
Regular assay analysis will assure the buyer that supplied nutrients — whether in the flour or in tablet or packet form — are really present at the levels claimed. Requesting vitamin and mineral assays should be a routine part of purchasing and processing operations at commercial bakeries, indeed at any food processing operation involved with fortified foods.