Abstract: A process for the preparation of white and brown sugar from raw diffuser beet juice. The juice is purified by membrane filtration at 70-95° C. on a filter having a molecular weight cut-off between 2,000 and 500,000 Dalton and evaporated to a dry matter content of between 60 and 80% by weight under vacuum to a thick juice. A conventional multi-step evaporative crystallisation of the thick juice gives crops of white and brown sugar crystals. The brown sugar obtained have valuable organoleptic properties.