Technological qualities of defoliated and topped sugar beet

Abstract

It is well known that beet with crown tissue have a higher content of melassigenic nonsugar substances than correctly-topped beet. However, there is a lack of information on the impact of this change on processing. Hence, the objective of this study was to determine the effect of defoliated beet on the different processing steps. Laboratory-scale processing experiments were conducted with defoliated and manually-topped beet from five sites in 2010/11 to 2012/13. Beet brei, raw press juice and thin juice have been analyzed, the subsequent effects have been simulated with a specially developed model. The results show that the beet composition changes increasingly when including a larger proportion of the crown tissue. Consequently, cutting off the first millimeters of the top of the crown will remove the worst part of the beet. Defoliated beet have a poorer technological quality compared to topped beet with a significantly higher content of melassigenic compounds, in particular -aminoN and invert sugar, and a lower pol. sugar content, thus resulting in a lower purity. This effect is similar for all products, beet brei, raw press juice, and thin juice. In thin juice, the effective alkalinity is significantly reduced, while colour and lime salts’ content are increased. Because of the lower quality/purity of defoliated beet more beet will have to be processed to produce the same quantity of white sugar, so the processing campaign will become longer. In the simulation model a lower thick juice purity and a higher molasses purity have been assumed for defoliated beet, as based on juice analysis and technological expectations. The higher content of nonsugars will result in an increased mass flow through the sugar house which will negatively affect the molasses exhaustion. At the same white sugar production, the simulation model calculates higher costs for processing aids and energy, but on the other hand also higher revenues for the additional production of pellets and molasses when processing defoliated beet.