Analysis of yellow sugar coloring substances from sugar beet production

Abstract

Coloring substances (colorants) adsorbing on the surface of growing sugar crystals or incorporating into the crystal lattice, reduce the speed of sucrose crystallization, increase the color and hygroscopicity of sugar, tend to clod during storage. Most of the colored nonsugars are found on the surface of yellow sugar crystals so it is possible to reduce the color of yellow sugar by 50-80% with the help of affinity. The distribution of coloring substances in the crystals of yellow sugar and their composition have not been studied sufficiently. The purpose of this research was to study the coloring substances of yellow sugar obtained during the sugar beet processing. As a result of the research it was found that up to 90% of yellow sugar coloring substances is in the film located on the crystals surface and can be easily removed by affinity. It was experimentally learnt that the main products in the coloring matter are the products of alkaline decomposition of reducing substances: their content is 10 times higher than that of caramel and melanoidins, which is in good agreement with the conditions for carrying out the technological processes of sugar beet production. The content of all groups of coloring substances correlates well with the crystals size: the least fraction of the colorants contains a fraction of 0.5 mm in size; in crystals of a larger and smaller size, the content of all groups of coloring substances increases. Yellow sugar coloring substances are extracted with acetic acid most effectively, because it is a weakly polar proton solvent. The noted absorption maxima for aqueous, acetate and ethyl acetate extracts do not coincide, which indicates the presence of various coloring agents in them..