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 maximized 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). 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 quite broad and are used mainly in nut based protein 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 (i.e. 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.
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 protein bar, they add a unique crunchy texture.