COOLING CRYSTALLIZATION OF SMB-FRACTIONATED MOLASSES

Fractionation of sugar beet molasses by the Simulated Moving Bed (SMB) Ion Exclusion Process is in commercial use in many countries. The sug ar-rich fraction (i.e. extract) obtained from this process is utilized in various ways during and after the regular beet campaign, Extract c ontains colorants which can complicate processes into which it is intr oduced. The colorants can be reduced using ion exchange resins, althou gh this can create other problems. An alternative approach is a crysta llization technique which enables the recovery of white sugar from hig hly-coloured syrups. For the latter approach, we used cooling crystall ization, as this has been successful with both highly-coloured syrups and untreated raw juice. In our laboratory, a 3-stage cooling crystall ization process was applied to the extract. Commercial white sugar was obtained from the Ist crystallization step, and by recycling the crys tals recovered from the 2nd and 3rd stages. Elevated levels of betaine and raffinose (both of which reduce sucrose solubility) enabled the r ecovery of a molasses which was similar to 93% exhausted by the crysta llization process. The crystallization data are presented, along with a working model describing the cooling crystallization process for the extract in a sugar factory operating independently of the regular bee t campaign.