Food Protein: Food Colour Interactions and its Application in Rapid Protein Assay

Saeed S. M.G., Abdullah S.U., Sayeed S.A., Ali R. (2010): Food protein: Food colour interactions and its application in rapid protein assay. Czech J. Food Sci., 28: 506–513. The uniform distribution of colours as additives in a majority of the food systems is a reliable indication that one or more components of foods are able to bind with colour molecules and act as their carriers. However, the food components acting as the colour carriers have not been identified. The present paper describes the binding capacity of Carmoisine with a variety of food proteins, our results have shown that the intensity, staining, and sharpness of the stained protein bands were excellent as compared to Coomassie Brilliant Blue R 250, which is an established staining agent for visualising electrophoretically resolved proteins. The data illustrates that Carmoisine is a fast reacting dye forming colour-complexes with all types of food proteins including curry leaves proteins. The protein bands are visualised within an hour which is useful for the initial immediate protein identifications. The experiments related to the staining of the resolved proteins with Carmoisine have shown that the dye is highly sensitive, rapid, and lasting. The food-dye can provide a quick protein assay as often desired in research works, the results may be later confirmed by using Coomassie if so required. In view of its strong binding with almost all proteins, it was thought that human proteases present in the digestive tract may not hydrolyse the bound proteins completely and may restrict the proteolytic digestion. However, the experiments based on the tryptic digestibility in vitro revealed that colour binding has no adverse effect on hydrolysis of peptide bonds by the intestinal proteases.