Binding ability of Allura Red with food proteins and its impact on protein digestibility

Allura Red-40 is a safe colour additive (permissible by the FDA and Health Canada) that is used in a variety of foods to make them more attractive and appealing for consumers. However, limited information is available about its binding to macronutrients that are responsible for its uniform distribution in food products. In the present study, the binding capacity of Allura with food proteins is compared with Coomassie Brillant Blue R 250, which is an established staining agent for visualizing electrophoretically resolved proteins. The data illustrate that Allura is a fast reacting dye and binds with a variety of food proteins including peanut, rice bran, garlic and mixture of proteins [(Takadiastase, nisin, a microbial protein and bovine serum albumin (BSA)]. The Allura bound proteins retained their colour at high and low temperatures and in a wide range of pH. The experiments on the resolution of proteins and staining with Allura have shown that the dye is highly sensitive, rapid, lasting and is easily linked with a variety of proteins. The binding of Allura to various proteins had almost no adverse effect on protein digestibility, as predicted by in vitro digestibility determinations.