Scale-up of native beta-lactoglobulin affinity separation process.

Affinity separation of beta-lactoglobulin in its native form with all-trans-retinal immobilized on calcium bio-silicate was scaled up and applied to separate it from industrial sweet whey. Three different methods of mixing the modified calcium bio-silicate and whey for the interaction between all-trans-retinal and beta-lactoglobulin were tried at pilot scale. The three methods used were 1) a column packed with calcium bio-silicate, 2) a stirred tank, and 3) a fluidized bed column of calcium bio-silicate particles. Adsorption and desorption of beta-lactoglobulin were carried out at pH 5.1 and 7.0, using 0.01 and 0.1 M phosphate buffers, respectively. The phosphate buffer containing desorbed beta-lactoglobulin was concentrated 20 times using ultrafiltration and then freeze-dried. The packed column, stirred tank, and fluidized bed column produced beta-lactoglobulin with purity of 80, >95, and >95%, and recovery of 0.65, 2.88, and 2.88 g per kilogram of calcium bio-silicate, respectively. The comparative poor purity and recovery of beta-lactoglobulin in the case of the packed column was attributed to insufficient contact between the passing fluids and the calcium bio-silicate during adsorption, desorption, and intermittent washing. The fluidized bed column method, with a gentle mixing action, was considered the best suited for further scale up to the industrial level.