In recent years, the nutrition-bar market has repositioned itself — low-carb and high-protein trends have been replaced by fibre and nutraceuticals. Lisa Bradford details the eight factors modern bar makers must be mindful of
The ingredient portfolio for bar formulators includes soy- and whey-protein combinations, dietary fibre, plant sterols, isoflavones and vitamin E. Regardless of the bar type, eight factors are crucial in bar development: protein source, sweetener type, fibre source, oil, emulsifier system, vitamins and minerals, nutraceutical options and flavour system.
In most instances, the protein source in a nutrition-bar system is derived from either dairy or soy protein or a combination of both. Both contain nine essential amino acids and have relatively high Protein Digestibility Corrected Amino Acid Scores (PDCAAS), 0.94 to 0.99 and 1.0, respectively. One advantage of combining dairy and soy protein is cost savings, since soy-protein ingredients are generally more cost effective than dairy-protein counterparts. Although the addition of soy protein may create issues in processing and sensory perception, these hurdles can be easily overcome with moderate protein addition, the correct ratio of other functional ingredients, and processing techniques.
Nutritional characteristics and functionality can be maximised in a nutrition-bar system with the wide variety of dairy- and soy-protein ingredients. Dairy proteins include calcium caseinate, milk-protein isolate, whey-protein isolates and hydrolysates (all >90 per cent protein) and also, milk and whey protein concentrates (>80 per cent protein).1 Whey-protein hydrolysates are optimal options for bar applications due to their low effect on bar hardening over the shelf life of the products.
Soy-protein offerings are just as broad and are used mainly in nougat-bar formulations. These include soy-protein isolates, concentrates and soy flour (90, 70, and 50 per cent protein, respectively). Hydrolysed soy-protein isolates and/or soy proteins with low water solubility are good options for nutrition-bar applications, due to decreased functionality (ie, water binding). Soy flour is often only used as a secondary protein source because of flavour and texture.
For particulate nutrition bars, textured soy-protein concentrate, textured vegetable protein and soy grits (70, 50, and 50 per cent protein, respectively) are also combined to achieve nutritional, functional and sensory properties. The effect of water binding of these ingredients is fairly low when analysed in a bar system. (See sidebar, "Factors affecting water-binding properties," below.)
Texture, flavour and appearance of nutrition bars can be enhanced by adding protein crisps — processed by thermal extrusion techniques using protein isolates in conjunction with a starch source. Protein crisps, both in dairy or soy, are readily available in various protein contents. They are fairly clean in flavour and contribute minimally to bar hardening. When added to the base of a nougat bar, they add a unique crunchy texture.
The sweetener system also plays a vital role acting as a glue, binding all of the ingredients. Sweetening agents also serve as the primary source of carbohydrates. Traditional sweeteners include corn syrup (42 or 62 dextrose equivalent) and high-fructose corn syrup (42 or 55 dextrose equivalent). Corn syrup is the main binding component whereas high-fructose corn syrup provides intense sweetness. Powdered corn sweeteners such as dextrose or maltodextrin are often incorporated to aid in binding.
Sugar alcohols can also be used as sweetening and binding ingredients. Because of their reduced sugar content, sugar alcohols can be used in bars marketed to consumers seeking low-carbohydrate and diabetic options.
Clean-label sweetener options in many bars today include brown rice syrup, agave nectar, evaporated cane juice and fruit.
USDA dietary guidelines indicate that the average American does not consume the recommended dietary allowance of 25 grams of fibre a day.2 Nutrition bars can easily be formulated to contain 2.5 (good source) to 5 (excellent source) grams of dietary fibre. Available fibre ingredients include inulin, polydextrose, soy and oat fibre. In some instances, fibre decreases bar hardening and extends shelf life. In a recent study, nutrition bars containing digestion-resistant maltodextrin (Fibersol-2) displayed significantly decreased bar hardening than those processed using 10 DE maltodextrin through month 12 of accelerated storage conditions.3
In most nutrition-bar systems, fats and oils comprise only a small part of the overall formulation containing only 2 to 5g of fat per serving. However, fats and oils enhance texture and promote flavour release. Food processors typically use vegetable oils such as canola, soybean or sunflower oil to fit their formulation needs. Palm-kernel oil is often used in coatings and toppings due to its solid structure.
When fat is added, an emulsifier is often incorporated to inhibit oil leakage. The most common emulsifiers in bar systems are lecithin and mono-diglyceride blends. During processing, emulsifiers and fats are combined, yielding a slurry. Slight heating may be required to blend the fat and emulsifying agent. Stability of the fat and texture of the final product are maximised by appropriate usage level of the selected emulsifiers.
Vitamin and mineral blends and nutraceutical ingredients are premium ingredients that add appeal and promote overall health and well being. Most nutrition bars are fortified with customised blends of vitamins and minerals such as calcium, iron, vitamin D and vitamin E added to achieve 30 to 35 per cent of the recommended dietary allowance. Vitamins and minerals are also inherent in some of the ingredients in the formulation, such as added protein, fruit pieces and nuts.
Individual nutraceutical ingredients boost appeal for target consumers. For example, isoflavones and calcium are staple additives to nutrition bars promoting women's health as they can ease the transition through menopause, reducing symptoms such as hot flashes.4 They may benefit the cardiovascular system by helping to maintain healthy arteries.5,6 Some studies also indicate that isoflavones can have a positive effect on skin health.7
Plant sterols are increasingly used as nutraceutical ingredients. Sterols naturally occur in vegetables and vegetable oils, in various quantities. They are waxy in nature and insoluble in water. Nutrition bars have minimal moisture, mainly contributed by the ingredients used to formulate them. Therefore, nutrition bars are excellent vehicles for formulating with plant sterols. During processing, sterols can be easily mixed with the dry-ingredients portion of the nutrition-bar system. Nutrition bars can easily be fortified with 400mg, the minimum required by the FDA health claim centered on plant sterols.
Omega-3s are another hot ingredient finding homes in bars, as are probiotics.
Achieving a well-balanced flavour profile, with minimal off-notes, is key to gaining consumer acceptance. Common flavour profiles in nutrition bars include vanilla, chocolate, strawberry, brown sweet milk/dairy, nut, fruit/citrus, coffee and spice. These particular profiles are also effective in masking bitterness and astringency that can be associated with some ingredients. Bitterness can be overcome by formulating with complimentary bitter brown sweet flavour profiles such as coffee and dark chocolate. The addition of a cooling agent, such as a mint flavour, can decrease the perception of astringency on the tongue.
Vitamins and minerals as well as nutraceuticals may cause off-flavours in nutrition-bar systems. Specific flavoured masking agents can decrease their effect. Encapsulation of flavours and vitamins and minerals are effective in protecting flavour. Also, proper storage of individual ingredients prior to use can decrease the effects of ageing, resulting in less off-flavour.
Lisa Bradford is a soy-foods technologist at Archer Daniels Midland, a full-line supplier of ingredients including ProFam brand isolated soy proteins, CornSweet liquid corn and high-fructose corn syrups, Clintose powdered corn-syrup solids, Novasoy isoflavones and CardioAid plant sterols.
1. Marshall R. Protein blends raise the bar. Functional Ingredients 2009 Feb;34-6.
2. U. S. Department of Agriculture, Agricultural Research Service. 2008. Nutrient intakes from food: mean amounts consumer per individual, one day, 2005-2006.
3. Boice BC, et al. Food bar with reduced hardness U.S. Patent Application Publication, US2005/0226960 A1, October 2005.
4. Kurzer MS. Soy consumption for reduction of menopausal symptom. Inflammorpharmacology 2008;16:227-9.
5. Hallund J, et al. Soya isoflavone-enriched cereal bars affect markers of endothelial function in postmenopausal women. Br J Nutr 2006; 95:1120-6
6. Lissin LW, et al. Isoflavones improve vascular reactivity in post-menopausal women with hypercholesterolemia. Vasc Med 2004;9:26-30.
7. Izumi T, et al. Oral intake of soy isoflavone aglycone improves the aged skin of adult women. J Nutr Sci Vitaminol (Tokyo) 2007;53:57-62.