Evolution of colorants in sugarbeet juices during decolorization using styrenic resins

Molecular size distribution of coloring impurities in sugar beet juices was studied in order to get a better understanding of the evolution of colorants during ion exchange decolorization processes using styrenic resins as well as to provide useful information about the influence of operating decolorization conditions and regenerant consumptions on the removal of harmful colorants. A study of resin life was also performed. Size exclusion chromatography (SEC) of sugar beet thin juices confirmed the presence of colorants with molecular masses above 100 kDa, 20 kDa and 2 kDa. The global color reduction percentages achieved in the decolorization stage were about 75–80%. The colorants with a molecular mass of 20 kDa were completely removed whereas components above 100 kDa and 2 kDa presented lower removal efficiencies, showing lower affinity for the styrenic resin. Colored impurities are likely to be related to melanoidins, Maillard reaction products. Low regenerant consumptions, about 57 L of solution per m3 of treated juice, removed adsorbed colorants from the styrenic resin without reducing its decolorization capacity considerably.