Continuous vinegar decolorization with exchange resins

Vinegar decoloring by adsorption with exchange resins was studied and the decoloring capacity of three commercial resins as adsorbent material evaluated. The regeneration of the resins was also studied. The decoloring capacity of the selected resin (Lewatit S-6328-A) was compared with a powder activated carbon which is currently used as an adsorbent in the vinegar industry for decolorization, For a batch process with white and rose vinegars with resin Lewatit S-6328-A (10 g/l for white and 20 g/l for rose) at equilibrium the maximum decolorization efficiency was 69% and 72%, respectively. In the continuous process with a packed column on bench scale, the pseudo-contact time (ratio resin volume and vinegar flow-rate) is the operation factor which determines the decolorization level. The maximum level of decolorization for white and rose vinegars in continuous process was practically the same. The pseudo-contact time required to obtain the maximum decolorization for rose vinegar was almost three times that required for white vinegar. The adsorption of coloured compounds with exchange resins in continuous packed columns seems to be technically feasible, and the results of this work form the backbone of subsequent studies of scaling up for vinegar decolorization. The possibility of packing the resins into a column means that a new continuous process can be used for vinegar decolorization. (C) 2002 Elsevier Science Ltd. All rights reserved.