SOLID PHASE ASSAYS TO DETERMINE THE BINDING TO PROTEINS OF SOME FOOD DYES CONTAINED IN COMERCIAL DRINKS OR IN BAKERY/PATISSERIE COLOURING ADDITIVES

ASENSIO, CRISTIAN; SANTA COLOMA TA,

MAR DEL PLATA

Congreso; LXIII Reunión de la Sociedad Argentina de Investigación Clínica (SAIC); 2018

(332) SOLID PHASE ASSAYS TO DETERMINE THE BINDINGTO PROTEINS OF SOME FOOD DYES CONTAINEDIN COMERCIAL DRINKS OR IN BAKERY/PATISSERIECOLOURING ADDITIVESCristian J. A. Asensio1, Tomás Santa Coloma11BIOMED-CONICET-UCADrinks, foods, candies, cosmetics and medicines are coloured withdifferent artificial anionic sulfonated azo dyes. There is a long standingdiscussion concerning the toxicity of these dyes and their effectson food digestibility as well as if they are really edible and safe. Aftermany worrying research reports, some countries banned certain dyeswhile they are still allowed in others. Simple methods to compare theprotein binding capacity and optimal pH or concentration of differentdyes would be a step forward to determine their binding constants/parameters and possible toxicity. Some dyes might bind proteins inthe stomach at acid pH by electrostatic interaction of basic residueswith the sulfonic groups while others might also bind proteins in thelower tract even at neutral pH through hydrophobic and/or non-ionicinteractions. Dyes might also access the bloodstream during gastrointestinalpathologies. Thus, we implemented solid phase assaysto quickly assess the effects of incubating milk proteins, BSA andbovine gamma-globulin directly with drinks and beverages includingisotonic drinks. 1μl of serially diluted protein samples was spotted 190 MEDICINA - Volumen 78 - (Supl. III), 2018on different surfaces in an arrayed manner. Dye binding was imagedand densitometrically quantified. Commercial isotonic drinkscoming at a pH of 2.6-2.9 were able to stain quickly, sensitively andlinearly the proteins regardless of the many other additives or preservativespresent in the drinks (sucrose, citrate, benzoate, salts,etc). Besides, dyes commercialized for cooking, bakery or patisserieas pastes or solutions were also able to stain proteins. Altogether,our solid-phase assays are a simple, promising way to compare thebinding of different food dyes dissolved in drinks or commercializedin pastes or solutions. The effects of pH, solvents, additives, dyeconcentration and protein types on dye-protein affinities/bondingcan be compared as a step previous to the evaluation of dye toxicityby other analytical methods.