How is sugarcane juice clarified before it is made into sugar crystals?

To clarify sugarcane juice before it is processed into sugar crystals, manufacturers use a process known as defecation.1

The raw juice extracted from the stalks is purified through the following steps:

• Neutralization: Heat and lime—a suspension of calcium hydroxide—are added to the juice. This neutralizes the natural acidity of the juice, preventing the sucrose from inverting into glucose and fructose, and kills enzymes.1
• Flocculation: Flocculation aids, such as polyacrylamides, are added to the heated mixture to help impurities clump together.1
• Separation: The mixture is pumped into a continuous clarification vessel. In this tank, clear juice is separated from the solid muds that settle at the bottom.1
• Filtration: The muds are sent to rotary vacuum filters to recover any residual sucrose.1

Once clarified, the juice is ready to be concentrated via multiple-effect evaporators for further processing.1