ABSTRACT
The fundamentals of adsorption as a separation, concentration, and puri cation technique in the food industry are discussed in this chapter. The process is analyzed from the phenomenological point of view, describing the main stages for the adsorption of a solute on the inner surface of a porous material: external and internal transfer and equilibrium. The most commonly used models to describe these steps are presented and commented on in terms of the uid-phase state: gas or liquid, and the possible applications. Then, the description of the properties and purposes of the most frequent adsorbents is given. The next section presents the different alternatives for the adsorbent regeneration after use because this step is crucial for the feasibility and cost of the whole process. They arise from diverse ways of altering the adsorption equilibrium such as increase in temperature, reduction of pressure, and the introduction of a purge or a desorbent. The different con gurations and operation methods to carry out the process at industrial scale are illustrated with the aid of industrial examples. The batch operation in agitated tanks is described. The continuous operation is presented in various possibilities: by using series of xed beds working with alternation of adsorption/desorption stages or by the utilization of simulated moving bed systems. The last section is devoted to brie y describing the main applications of adsorption in the food industry. Essentially, this operation is used to remove pigments, odors, and other kind of impurities. Finally a summary of novel separations and new procedures where adsorption is combined with other techniques is presented. A separate section is included at the end to discuss the use of adsorption in the selective recovery of bioactive compounds from crude solvent extracts. In most cases, the target compounds are polyphenols that are separated from plant wastes because of their potential health bene ts.
