Etapas de nucleação e cristalização e avaliação de parâmetros deprocesso na fabricação de açucar

Abstract

This study aims to present the sugar manufacturing process from sugarcane, with an emphasis on the nucleation and crystallization stages of sucrose, which are considered fundamental to the efficiency of the sugar mill and the quality of the final product. Initially, concepts related to the raw material and the main processing steps—such as extraction, juice treatment, and evaporation until syrup formation—will be discussed. The main focus of the study will be on the physicochemical mechanisms involved in nucleation, defined as the initial organization of sucrose molecules into stable structures, and in crystallization, where the growth of these nuclei occurs. It will be shown that supersaturation acts as the driving force behind these phenomena, being influenced by variables such as temperature, liquor purity, massecuite viscosity, and the presence of impurities. Among these impurities, dextran will be analyzed for its dual role: while it promotes nucleation by reducing free water, it hinders crystal growth by increasing viscosity and restricting diffusion. The solubility zones (unsaturated, metastable, intermediate, and labile) will also be described, highlighting that ideal crystallization occurs in the metastable region, as it allows crystal growth without excessive nucleation. Mathematical models will be developed to quantify the crystal growth rate and the free energy involved in nucleation, enabling an assessment of how proper operational control can prevent the formation of small and heterogeneous crystals, which impair centrifugation and reduce sucrose recovery. Furthermore, industrial schemes for boiling and centrifugation will be analyzed, emphasizing strategies that ensure effective exhaustion of the mother liquor and uniform crystal distribution. It will be verified that precise control of process parameters is essential to optimize production, increase recovery, and ensure the uniformity and quality of the sugar.