Understanding the causes of calcium carbonate crystal growth and inhibition during the carbonatation refining of raw sugars

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The inhibitory activity of soluble and insoluble starch (0-550 ppm/Brix) in factory raw sugars were investigated using simulated refinery carbonatation clarification reactions to underpin what causes the undesirable formation of CaCO crystal fines (≤5 μm). It was found that CaCO crystal growth was inhibited mostly by soluble starch by forming starch-Ca metal complexes. Insoluble (granular) starch, however, had a greater affinity for inhibiting CaCO crystallization because it retained the carbonatation clarification reactants, i.e., Caand OH, in the granule interior which caused granule gelatinization and increased viscosity of the melt liquor. Causes for poor press filterability and CaCO fines using raw sugar melts were found to be complex and attributed to the combinatorial roles that both soluble and insoluble starch have, among other impurities. More studies are now warranted at the carbonatation refinery to correlate processing characteristics with raw sugars quality attributes to underpin how each impurity impedes carbonatation.

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Food chemistry

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