Removing starch from cassava, often referred to as cassava starch extraction, is a process that separates the valuable starch granules from the fibrous root material. This is typically done through a series of mechanical and physical steps.
The Process of Cassava Starch Extraction
According to general procedures, the extraction of cassava starch from cassava roots involves several key stages. These steps are fundamental whether the process is performed manually or using automated industrial machinery.
The primary steps include:
- Cleaning: Removing initial dirt, sand, and debris from the harvested cassava roots.
- Washing: Further cleaning the roots with water to remove remaining surface impurities.
- Crushing: Breaking down the cassava roots into a pulp to release the starch granules.
- Separating: Isolating the starch milk (a suspension of starch in water) from the fibrous residue. This often involves sieving or screening.
- Concentrating: Increasing the density of the starch milk, often by settling or centrifugal methods, to remove excess water and soluble impurities.
- Dehydrating: Reducing the moisture content of the concentrated starch slurry. This can be done using methods like filter presses or vacuum filters.
- Drying: Further reducing the moisture content of the dewatered starch cake to a stable level, typically using flash dryers or other industrial drying equipment, resulting in a dry starch powder.
These seven steps — cleaning, washing, crushing, separating, concentrating, dehydrating, and drying — form the core process for effectively removing starch from cassava roots for various uses.
Step-by-Step Breakdown
Let's look closer at each stage:
- Preparation (Cleaning & Washing): Fresh cassava roots come from the ground and carry dirt. Cleaning involves removing the outer skin and larger debris, while washing uses water to get rid of stubborn soil and contaminants. This ensures the final starch is clean.
- Pulping (Crushing): The cleaned roots are ground or rasped into a fine pulp. This action breaks open the plant cells, liberating the starch granules trapped inside.
- Extraction (Separating & Concentrating): The pulp is mixed with water, and this slurry is passed through screens or filters. The fine starch granules and water pass through, forming starch milk, while the coarser fibers are retained. The starch milk is then further refined and concentrated to remove proteins, soluble sugars, and excess water.
- Dewatering (Dehydrating): The concentrated starch slurry still contains a high percentage of water. Dehydrating machines remove much of this moisture, turning the liquid slurry into a damp solid or cake.
- Finishing (Drying): The final step involves drying the damp starch to a low moisture content (typically 10-15%). This is crucial for preventing microbial growth and ensuring the starch's stability and shelf life.
By carefully following these steps, the pure starch is successfully separated and obtained from the raw cassava root.
