Primary recovery of acid food colorant

Summary The sorption behaviour of the natural colorant carminic acid onto a macroporous type weak anion‐exchanger was evaluated in a finite bath contactor. Sorption equilibrium and kinetics were studied to characterise the system. Adsorption isotherms were found to be of the favourable type and to follow a Langmuir expression. Sorption kinetics profiles were obtained as a function of the stirrer speed, resin load and dye concentration in the liquid phase. Analytical equations were found for quantitative description of the system and to further assist in process scale‐up. Fluid‐side mass transfer phenomena, as well as, intraparticle resistance mechanisms were revealed. This was described in terms of a film mass transport coefficient and a (modified) pore diffusivity. Calculated Biot number for the system showed combined mass transfer resistance effects. A high quality carminic acid preparation was attained showing no allergenic properties and having no content of metal ions.