Colourants - Formation - CarbonatationTopics:
By Bento, Luis San Miguel
Posted on 2007-07-20 Last edited on 2009-09-19
In Carbonatation, when liquor is mixed with lime, pH increases to values higher that 11. At this alkalinity, invert sugars can be decomposed with formation of HADP. The formation of this kind of colourants was detected by GPC analysis with ELS detector (Bento, 1999).
Quantification of HMW Compounds using PEG as internal standard (ppm on brix)
As it was as proved, these compounds are difficult to remove from ion exchange resins, and tend to stay irreversibly fixed to the resin. Also, these compounds remain in white sugar (Bento and SÃ¡, 1997). Due to these facts it is very important to avoid the formation of these compounds during Carbonatatin.
A process was studied to reduce this colour formation. In this process, calcium hydroxide added to affined liquor was reduced. As part of calcium carbonate works as filter aid, this part was added to the liquor, as calcium carbonate. This calcium carbonate was prepared by making a previous carbonatation of calcium hydroxide, before be mixed with liquor (Bento, 1999). It was observed that by replacing 40% of calcium hydroxide by an equivalent quantity of calcium carbonate recently precipitated, a decolourization of 52% in carbonatation was obtained and peak C reduction, equivalent to HADP formation, was observed.
ELS diagram of liquor before an after Carbonatation
Bento L.S.M., 1999, Study of colour formation during Carbonatation in Cane Sugar Refining using GPC and
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