The quality of sugar production in sugar beet factories depends on many parameters, in particular on the properties of sugar syrup (thick juice). The aim of this study is to investigate negative effects of dextran presence during the crystallization process on growth rate of sucrose crystals in pure sucrose solution at different temperatures. To elucidate the influence of dextran presence on the growth rate of sucrose crystals, different molecular weight fractions of dextran from 40,000 g/mol (T40) to 2,000,000 g/mol (T2000) were admixed in different concentrations to pure sucrose solution. The most pronounced effect of dextran was found with T2000 at concentrations of 1500 and 5000 ppm at 60 degrees C. On contrary, negligible influence of dextran T40 and T500 was observed at the same temperature and supersaturation. From the results it could be shown that a decrease of crystallization rate of up to 50% with dextran admixture, compared to crystallization rate with pure sucrose solution, could be obtained. Such a negative influence extends crystallization time in the sugar house and thus increases the production costs. (c) 2007 Elsevier Ltd. All rights reserved.