Energy and health bars - particularly those offering significant nutrition - are growing in importance as light supplements for athletes during performance, and as snacks for working people during a typical marathon day. As part of a total dietary nutritional approach, these high-density performers can offer significant nutrition and health when properly designed.
Designing an energy bar focuses on primary functions of exercise, whether moderate or extremely demanding. As the demand curve increases, vital functions of metabolism and protection increase. Energy bars offer antioxidant protection as well as protein synthesis and restoration.
Health bars emphasize timed delivery of vitamins and minerals, availability of nutrients and favorable sensory scores. Designing these bars primarily involves: determining processing equipment and conditions to deliver the desired profile; setting the desired texture and nutritional targets; designing a balanced flavor system; developing a packaging system to limit oxygen and moisture flux; and determining shelf-life factors.
"We put together five points of what we consider the functions of food," says Paul Paslaski, marketing manager, Roche Vitamins, Paramus, NJ. "If you're going to have a functional food, you're going to have to think about what a food delivers. One, food sustains physiological and psychological life. Two, it supports growth and maintains the body's structure. Three, it provides energy. Four, it promotes organ repair and replacement of tissues like bones. Five, food enhances the body's various functions and helps protect the body's key functions, such as the cardiovascular system, and the nervous and immune-response systems."
Designer's Shopping Cart
Shopping for ingredients requires consideration of energy, nutritional importance, taste, compatibility of ingredients, actual vs. perceived effects, handling characteristics and costs.
Carbohydrates provide the primary energy source. The options are extensive, although the cellular-level fuel is glucose. Glucose is available as a powder, high glucose and regular corn syrups, and in fruit juices. Glucose also can be made available to the cells by hydrolysis and enzymatic conversion of fructose, maltose, lactose and other sugars. The delay of availability due to intermediate reactions allows some extension of glucose metabolism during intense exercise. Maltodextrins, polymers of glucose, are readily hydrolyzed, yielding glucose. Maltodextrins are a low-density, high-glucose source, providing a smooth texture.
Inulin and oligofructose (OF) are polymers of fructose, often with a terminal glucose molecule. High solubility can build structure and extend shelf life in bars. Inulin and OF act as dietary fibers. Scientific studies show a caloric value of 1.5 kcal/g for inulin and for OF. "OF has a very nice sweetness profile," says Mark Izzo, director of technology, ORAFTI Active Food Ingredients, Malvern, PA. "When used in combination with high-intensity sweeteners, OF lends a sweetness profile similar to sucrose, building slowly to its peak and tailing nicely. The sweetness is about 30% that of sucrose, so a possible application would be to decrease sweetness in a food where fat has been replaced by sugar."
Daily consumption of OF and inulin increases the level of beneficial bifidobacteria in the intestinal tract. The genus is able to produce a fructase enzyme, allowing proliferation of bifidobacteria. They become the predominant microorganism while decreasing potentially harmful organisms such as Clostridium due to competitive inhibition. Additionally, in vitro studies have shown a bifidobacteria protein with antibiotic properties inhibiting potentially harmful bacteria.
Other health benefits of inulin and OF under study include decreased blood triglyceride levels, increased calcium absorption and utilization, protection against certain cancers, and possible stimulation of the immune system.
Adding OF to nutrition bars results in taste improvement, sweetness and binder characteristics. OF might improve satiety, or feeling of fullness/satisfaction - a major plus for snack foods. The suggested OF use level in bars is 8 grams per portion or 15 grams per day. Inulin may be used at 10 grams per portion or 20 grams per day, Izzo says.
Proteins are the most important macronutrients, vital to all body systems. Although a normal, healthy adult needs only about 2 oz. total protein daily, this must be consumed in the right ratio of amino acids. The Protein Digestibility-Corrected Amino Acid Score, taking into account essential acid profile, digestibility and provision of essential amino acids for human nutritional needs, sets the standard. Scoring rates 1.0 as the highest in balanced protein. Isolated soy protein, egg whites and casein rate 1.0, with beef protein at 0.92, rolled oats at 0.57, and whole wheat at 0.40.
When designing a health or energy bar, sources of protein can be blended to achieve protein balance, texture, appearance and flavor. Pure amino acids also might be used. However, plant products such as soy and grains carry other vital nutrients, phytochemicals and fiber.
Soy products are available in numerous forms, including isolated soy protein, soy protein concentrates and soy flour. The defatted products have high moisture absorbency, requiring additional water for hydration. Textural effects will vary greatly with ingredient blends, but in general proteins can increase glass transition and product chewiness. Solubility, wettability, water absorption and emulsification properties can be exploited. Usage levels can be more than 25%, at relatively low protein costs.
Fruits provide color, flavor, texture, carbohydrates, vitamins, minerals, fiber, antioxidants and other phytochemicals. The anthocyanins in cherries and berries have antioxidant properties. Vitamin C and polyphenolic compounds in grapes and apples exhibit antioxidant properties as well.
Fruit ingredients are available in many forms - as purees, juices, pulps and dried powders. "As high-solids ingredients, they have many applications in bars," says John Nobile, vice president of sales, Gilette Foods, Inc., Union, NJ. "Concentrates can be spray-dried with maltodextrin. We also have a drum-dried products, supplied as flakes or ground powders."
Vegetable products also might be used, alone or in conjunction with fruits. Vitamin, mineral, fiber and phytochemical benefits can be obtained, but focus must be on the flavor, for off-notes or earthy notes can be difficult to mask, according to Nobile. "An extensive line of vegetable products from the more mundane, like spinach and broccoli, to somewhat exotic products like rhubarb and corn are tasty and useful in bars," he says.
When designing with complex plant products, we must be aware of the dual-edged blade of many plants. USDA's Agricultural Research Service and biochemistry departments of major universities can provide available information on the use and status of given materials. Information on botanicals can be obtained from the British Pharmacopeia as well.
Energy bars can be formulated with oats and oat extract, said to stimulate the central nervous system. Other stimulant botanicals include coffee, tea and guarana - all containing varying levels of caffeine and other alkaloid stimulants. Extracts of coffee and guarana are useful flavor elements. Extracts of American, Asiatic, and the unrelated Siberian ginsengs are said to stimulate the brain, heart and blood vessels. They increase blood corticosteroid levels, which aid muscle efficiency and carbohydrate metabolism. South American stimulant extracts include yerba mate and gotu kola, with their caffeine and additional alkaloid stimulants. Yerba santa is a potentially useful extract for reducing bitterness associated with botanicals.
"One thing you have to consider with natural products is that there are a lot of factors that limit quality," says Yollie Nasca, technology services manager, Ashland Nutritional Products, Irvine, CA. "The soil conditions, growing conditions, the harvest process, handling, and the extraction method all determine quality. Extensive testing with HPLC and other methods are used to check products." Standardizing is required to ensure that products deliver consistently known quality and safety.
"Green tea extract has been standardized to 30% polyphenols," Nasca says. "Some researchers have found anti-viral activity during screening of viruses. Tests are under way to determine types of viral strains that can be affected by polyphenols. Green tea has the benefit of strengthening arterial vessels, which is of great interest in improving cardiovascular health. Another familiar product is gingko leaf, long used in the Orient. It is standardized to 24% gingkoflavon-glycosides. It is said to improve memory by increasing blood flow specifically to the brain."
Grains are available as whole-rolled, flake, meal and crisped forms, allowing many different textures and applications. Finely sized flakes yield good texture, while meals or flours contribute binding capability, some flavors and ease of assimilation. Crisped grains add texture and flavor.
In theory, any grain providing taste and texture can be a part of a design. Ancient grains offer potential for 2,001 designer foods. Quinoa and amaranth could join popular and cost-effective grains, including wheat, rice, oats, barley and corn, as nutritious and desirable ingredients.
"Rice is a source of high-quality protein, having all the essential amino acids present in desirable proportions," says Don McCaskill, director, R&D, Riceland Foods, Inc., Stuttgart, AR. "Compared with other major cereal grains, rice protein contains a fair amount of lysine. In addition, preliminary work at the University of Massachusetts, Lowell, indicates rice protein might be effective in reducing serum cholesterol."
Use of crisped rice, made from brown or milled rice, improves bar appeal due to its crunchy texture, toasted flavor and bulking capacity. "There's been some hesitancy on the part of users to include crisped rice," says Dean Oliver, pilot plant coordinator, Riceland, "due to concerns about moisture gain and loss of texture during storage." Typically, there are enough other hygroscopic ingredients vying for water in a bar that this should not be a problem, McCaskill says.
Oats lend texture and phytochemical fine-tuning. They are another high source of fiber (10%), with low fat levels of 7%. The soluble and insoluble fibers can be significant reducers of serum cholesterol. Oats can be used as rolled flakes or in meal form.
Barley has a relatively high protein level of 12%. It also boasts a high beta-glucan content, said to show significant cholesterol reduction, and, as malt, provides flavor.
A high beta-glucan (16%) barley has been shown to reduce cholesterol totals in tests run at Montana State University, says Bill Bonner, director, technical services, ConAgra Oat Processing Company, Omaha, NE. The total dietary fiber of the company's barley strain is 36% to 40%. Another component of the new barley is being studied as well, says Bonner. An isomer of a-tocopherol, alpha-tocotrienol has been indicated as a potential inhibitor of an important cholesterol synthesis enzyme. A study of alpha-tocotrienol indicated that the cholesterol reduced was mostly low-density lipoproteins.
Mineral fortification presents issues involving reactions, taste issues, usage levels, toxicity concerns, degradation of vitamins, flavors and colors. Mineral availability in the complex bar system is the key issue. Reactivity with vitamins, flavors and other ingredients needs to be determined prior to making finished product. Dicalcium phosphate is commonly used as a source of both elements. Other salts, such as lactate, citrate and gluconate, can be used as well. Zinc and magnesium can be used as the oxide. Copper gluconate and ferric orthophosphate are often used as ingredients, but the zinc-to-copper ratio must not become too high, because high zinc levels can lead to copper deficiency. Balancing is very critical, especially in relation to the rest of the diet.
"We came up with the term 'wellness foods' as a term describing ways to maintain optimal health," Paslaski explains. "Our largest product is vitamin E, but only 2% goes into food. 78% of consumers take 400 international units (I.U.) in the morning. Now think about bioavailability. If you don't have any fat in your breakfast or at any other meal, bioavailability is down. Taken over the day with a moderate level of fat, the bioavailability goes up."
Essential for carbohydrate, fat and protein metabolism, the B vitamins are therefore required during exercise and throughout the day for optimal performance. B vitamins are water-soluble at levels used. The stability varies by pH, generally lowering at higher pH levels. They are sensitive in general to heat, reducing/oxidizing substances and light, although tolerance varies. Thiamine hydrochloride exhibits an off-flavor and off-aroma.
Vitamin E is a potent antioxidant during exercise or through the day. It also might help strengthen the cardiovascular system. As with some other vitamins, vitamin E is toxic in higher doses, and is best taken in the proper dose, which is 30 I.U., over time or 10 I.U. per meal. The most stable form is dl-alpha-tocopherol acetate, which is oil-soluble, allowing incorporation in lecithin or emulsified oil.
Other vitamins have value in health bars. Vitamin A is active in growth, vision, bone and skin, strengthening and immunity enhancement. This may be added as vitamin A palmitate, or more conveniently as b-carotene, as the body will make only the vitamin A it needs from carotenoids. Formed in the skin, vitamin D aids uptake of calcium and phosphate, and provides strong bone growth. Vitamin D also can be toxic in higher doses. It is oil-soluble, and added as cholecalciferol (D3).
A strong antioxidant, vitamin C increases resistance to infections and speeds wound healing. Ascorbic acid or the sodium and calcium salts are water-soluble. Stability is affected by its strong reducing property.
Linoleic acid, an essential fatty acid, isn't synthesized by the body, and the diet requires ample supplies. Part of a bar formulation can consist of oil rich in this fatty acid to assist in vitamin uptake. This fatty acid is subject to rancidity, and must be protected with antioxidants.
Monounsaturated oleic acid is found in almond, soy and other seed oils. It is believed to assist in cholesterol reduction when part of a balanced diet.
Oils aid in lubricating and developing smoother texture when used at appropriate levels in health bars. They contribute a smooth, even break and help to carry some flavors. At low levels, they might tend to convey a sense of satiety.
"If you want to make an energy or health bar, you should consider including soy lecithin," says Dr. Fan Zhang, research chemist, Riceland Foods. "Lecithin acts as an emulsifier in binding the fat- and water-based nutrients and flavorings together. It is also a good source of choline, which was recently included in the dietary requirements by FDA.
"Choline is recognized as beneficial to liver and heart functions, as well as enhancing physical performance," Zhang explains. "Lecithin is required for synthesis of choline, one of the vitamin B group, which is found in brain tissue. There appears to be a role of lecithin in memory functions in brain cells. Lecithin is ideal for both functional and nutritional contributions."
Lecithin acts as an emulsifier for oils and oil-soluble vitamins. Studies are being conducted to elucidate lecithin's role in more rapid muscle recovery following vigorous exercise. The ingredient is available as a liquid and as dry ground powder, which is about 97% phospholipids.
Taste of Success
The total formulation has to be designed with the ultimate flavor profile in mind. This process requires examining the possible ingredient interactions of components. Choice involves the right combination to deliver the optimal flavor notes, preferably a relatively long-lasting expression of dominant notes in harmony. "A lot of bars have low acid, and in order to get a strong flavor impression, they tend to over-flavor them," says Stephen Wolf, director of flavor applications, Robertet Flavors, South Plainfield, NJ. "We try to encourage our customers to work with well-established vitamin/mineral or nutritional firms to make the various claims as far as the NLEA goes.
"We don't find it difficult from a flavor application product development side," Wolf says. "What happens is very often we start working on a product before the product developer or his/her marketing group has finished deciding what they want to deliver in a bar, as far as vitamins and minerals. For instance, suppose we have a flavor that works with a product having a fat-soluble core containing fat-soluble vitamins and the water-soluble vitamins in the exterior, and the system works pretty well. Then they come back and say they want to go from a 100 g bar to a 60 g bar, and deliver the same RDI. With the increase in vitamins and minerals, we have to develop a new flavor system."
Inclusions in energy/health bars not only add flavor and texture, but significant nutrition as well. These might include crisped-grain products, particularly rice, seeds and nuts.
Roasted nuts and seeds add crunchy texture, delicious flavor and noteworthy nutrients in the forms of vitamin E, minerals and protein and oils. This ancient food source can be employed in bars as shreds, granules, meal and butters. The butters are good carriers for fat-soluble vitamins, and consist of the kernels ground into a fine paste. Powders and butters would be a preferable for formulation into an energy bar intended for consumption on the run, the finer particles being easier to consume. For a nutrition bar, the texture and taste of the flakes or granules would be a desirable addition.
"In addition to 32% of the RDI for vitamin E, almonds have a significant level of monounsaturated fat, equivalent to olive oil," says Sam Cunningham, director of R&D, Blue Diamond Growers, Sacramento, CA. "This composition may have positive effects on cholesterol reduction. As almonds also have significant arginine (2.6%), this amino acid presence might help to prevent cholesterol deposition." According to Cunningham, 1 oz. of almonds consumed daily, containing 160 kcal, and used as one source of fat in the diet, might allow weight loss. Some weight-loss studies indicate that almonds provide a degree of satiety, aiding in appetite control.
Rolling the Bar Stock
Preparing the bars involves a series of procedures as varied as the products, taking into account texture, formulation and processing.
First is the overall texture desired - dry/baked, firm with bite, chewy, chewy/sticky or an intermediate texture. Bar texture is influenced by at least three factors: water activity (Aw), glass transition and inclusions.
Aw, or available water in the formulation, greatly affects product shelf life. In addition to texture, Aw also affects microbial spoilage, nutrient stability, flavor changes, and enzyme and chemical reactivity. High water activity, above 0.90, allows growth of normal food-spoilage organisms. However, many organisms can grow below that level, including molds, some of which can grow at 0.60 to 0.65.
The process becomes one of choosing carbohydrates to reduce the Aw below 0.65, while attaining the desired texture. Some solutes for Aw reduction include sucrose, fructose and glycerol.
The first line of defense for maintaining Aw is the package material. The moisture barrier maintains equilibrium moisture in the product. The product must be at equilibrium point at sealing. The equilibrium is the desired moisture level, independent of ambient moisture.
Water activity only provides a partial picture regarding bar-product stability. Glass transition, or the transition point from crystalline to a fluid state, is critical for meeting textural parameters. Available water, time and temperature all affect the glass transition. In bar products, it's common to use simple carbohydrates to lower water activity. However, low molecular weight compounds lower the glass transition. Higher molecular weight compounds, for example soy protein, increase the glass transition. The higher the glass transition, the more fluid the state of the product. For a softer chewy texture, the glass transition has to be increased. "Whether you want chewy, crisp or crunchy, you adjust the glass transition to meet the desired texture and stability parameters," says Judy Saslow, consultant, United Soybean Board, Seattle, WA. "Once you get beyond Aw and microbiological concerns associated with available water, you need to look at available water for the glass transition. You want to stabilize the target texture. When adding soy protein, you want to look at the total picture. Simple carbohydrates will lower the glass transition, and soy proteins, being higher molecular weight compounds, assist in increasing the glass transition."
Other techniques enhance shelf life. Oxygen-barrier film or laminate helps prevent mold growth. Another approach involves using potassium sorbate at pH levels below 4.0 to activate the sorbic acid. This might be used with fruit flavors, but precludes chocolate. For higher pHs, coating the bar with an edible food gum such as xanthan or carrageenan, or a protein like zein, might be the answer. This coated product will be dipped into a solution or spray-coated with potassium benzoate at levels up to 0.3%. This allows an acidified surface concentration to provide an active coating against molds, without bleeding into the bars.
Energy/health bars are prepared by several processes. Some products are sheeted, such as granola bars. Others are cold- or hot-extruded while heated, with the extrusion process itself generating some heat. The products are tempered, allowing cooling, moisture equilibration and texture stabilization prior to packaging.
Enrobing with typical chocolate- or vanilla-flavored compound coating might aid in moisture retention. A reasonably stable coating prevents melt problems. Also, as long as the enrobing compound is fairly stable at 100°F, coatings can help prevent stickiness. Current innovations include coatings employing yogurt formulations, grains and fat-replacing carbohydrate coatings.
Arriving at the desired texture and sensory profile involves designing the product according to the processing equipment. "In mixed systems where there is no concern about ingredient integrity, the process is much less involved," says Philip Katz, president, Shuster Laboratories, Boston. "There are situations in the extrusion process where you're concerned about heat vs. time of the mixing." Heat-processing might diminish certain vitamin levels, flavors and affect water levels and texture. "Then there are surface phenomena to be considered during extrusion that might define the tempering process. The other thing to be concerned about is reaching an equilibrium, and finding how long that takes. Tempering tunnels help to set the product. The tenderness and machinability become a critical issue. You really have to pay attention to the process."
The keys to providing a healthful nutrition or energy snack are balanced nutritional parameters, added value regarding nutrients, good stability and excellent taste. Better designs result from verifying that all ingredient provide proper nutrition and determining interactions, processing conditions and shelf-life factors at the start.
Photo: Cherry Marketing Institute
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